Original subtitles

[Music]

thank you

Network fundamentals basic Network

Theory and terminology

Network fundamentals is our first lesson

since before we can get into discussing

networking and its complexity

we need first need to Define some of the

terms some of the theory and get a nice

framework for where we're going to be

going

one note about the network plus exam is

that they assume you have around 18

months experience in the industry if you

don't that's okay but I am assuming that

you do have some basic knowledge of

computers and perhaps some working

knowledge of networks so in some cases

this might be redundant for you and in

other cases you might be learning some

new stuff either way I'm going to focus

on exactly what the network plus exam

wants to see and

what you need to know to pass

so in this module we're going to be

introduced to networks and what makes up

a network

the terminology that's used to describe

those objects it becomes flexible after

a little bit of time and experience

spent on the field but to understand

what each object does and what its

functions are in a network I want to

break down some of the jargon or the

technical speak and talk about what

exactly is networking

so some of the module objectives that

we're going to cover are first to Define

and describe a network and a computer

network you've heard the term Network

before and so I want to Define what that

is and how that relates to a computer

network

next I want to describe the components

of a network what makes a computer

network

I want to define the terms node and

server which will be helpful going

forward when we use those terms

Define and describe the network backbone

and the various variations of a network

backbone and finally

I want to define the difference between

a terminal

a client and a peer

all right so let's get started

now because networking is ubiquitous we

need to define a few specific things in

order to keep things in order

so first Network

this is an interconnected or

interrelated chain group or system

generally based on a purpose so for

instance if we say that you're going to

Facebook or LinkedIn are social

networks because the purpose is to be

social

and to connect with other people who

have similar interests likes Etc

in the same way you are interrelated and

you form a group

now based on that a computer network is

the interconnecting of two or more

computers that have a basic core purpose

of communicating electronically

so the network of social network is to

communicate with individuals about a

specific topic on a computer network we

need to communicate data electronically

and that's the thing that joins us

together

the internet is one really large

computer network and we will see how

that comes to play later on in this

course

now whether your network is comprised of

two computers or two thousand computers

or like the internet two million

computers there are uh some

commonalities in networks and

requirements for what makes them the

first thing that are needed obviously

are devices these are the actual

computers the printers the switches the

routers all of the devices that are

going to be connected together by

media now media can either be a physical

connection such as copper or newer forms

such as fiber optics

or it can be something Wireless like

Wi-Fi or a radio frequency or even

cellular Wi-Fi

each device however has its own language

when networking and not every device

knows how to communicate with the

language of these other devices right

because obviously a computer

communicates slightly differently than a

printer slightly differently than a

router Etc so in order to allow all

these devices to communicate with the

rest of the network we have something

called a network adapter sometimes

referred to as a network interface

controller or a NIC

specifically in the term of computers

and it serves this network adapter as a

translator between the components the

devices over the media by which the data

is sent

so finally to manage and govern how

everything talks with everything else

the network needs an operating system

which is similar to like the ring leader

in a circus if we can use a a metaphor

there

it tells the network how to work

together in order to perform as

efficiently as possible over the adapter

over the media and with each of the

devices without the operating system

there wouldn't be any order or Direction

in the network and no one would really

know what they were doing so the network

operating system is responsible really

for allocating resources

monitoring the activities of devices on

the network over the media

and managing files and data Etc

now we have two devices that I want to

Define one is a node and a node is any

device that is connected to a

Communications Network

and this can be just about anything so

we have uh clients and servers our nodes

and so are printers and network attached

storage devices and these are all what

we call

endpoint nodes I'm going to write that

up here

because that's where the data ends

whereas something like a router

or switch or previously we used to see a

lot of hubs do what's called

redistribute

so those are what we call redistribution

nodes okay so it's important to

understand that these are both nodes

anything on the network really any sort

of device that's communicating is a node

or being communicated with

the endpoint nodes where or where the

information sort of ends up or is going

to a redistribution node its

responsibilities to pass the data on to

another either redistribution node or

onto the endpoint node

now a server

is a network device that's responsible

for sharing resources and managing

certain services

like addressing and we'll talk about

this which is called an IP address a

little later

it's also uh manages devices on the

network and controls the network-wide

functions like permissions so not only

is it going to give uh all our clients

all the other nodes addresses that allow

it to communicate it's also going to

manage how those devices communicate and

what they're allowed to do which is what

we call permissions

all right now this is

um so you can see that the server is a

type of node but I just want to describe

server we're going to talk about some of

the other

um devices in just a moment before we do

that

let's talk about the network backbone

okay the network backbone is responsible

for carrying the majority of network

traffic and it works very quickly at a

very very very high speed

now it might use different technology

throughout this um on the backbone

that's different from the rest of the

network because it basically connects

all the smaller networks together

that's why it's called the backbone and

it needs to be large fast and

um

capable of communicating at very high

speeds because all of these computers

all these smaller networks are

communicating we'll talk about how that

all works in a bit now there are four

different types of network backbones and

we're gonna I'm just gonna give you a

brief definition of these now and we

will come back and talk about these more

in depth a little later okay the first

one is called serial that's where one

backbone cable

connects

to another one after the other

like so

all right so there's one backbone cable

and multiple switches are connected to

that cable

which allow devices to connect to it

there's also something called a

hierarchical or distributed uh

um backbone which like a family tree it

has more of a family tree layout if you

can imagine right

okay and this backbone is in this case

it's much easier to manage typical for

what we'll call local area networks or

lands it's much more easily scalable as

you can see because I can update one

part a lot faster and in this case the

backbone is responsible for the traffic

of the nodes on each branch so we have

different branches and on each branch

the backbone is responsible for that and

that's how it gets a little easier now A

collapsed uh backbone uses a router as

the Connecting Point all right and we'll

talk more about how that works a little

bit later and what exactly a router does

and how that's different from a switch

and that's a pretty major point

finally we see something called parallel

which is just like a collapsed uh

backbone except it has multiple cable

connections and that's because that

allows for more redundancy remember if

you took the A Plus Class we talked

about redundancy and how we want to make

sure uh that we don't have what are

called single points of failures so

there's more than one cable connection

which not only is great for redundancy

it also allows for what's what we call

load balancing and also a faster

throughput because the computer can

decide which of the cable connections to

use all right so these are again we have

serial hierarchical or distributed

collapsed in parallel as we talk more

about networks these differences will

become clearer but I just wanted to

cover them now and you won't probably

see these specifically on the exam in

this format you'll see them in other

formats and but I want to lay the

framework for what we're going to be

talking about

all right now a terminal

terminal is a network Hardware device

that's used for entering date data into

it and displaying data from another

computer Computing system

it's commonly called a dummy computer

because it doesn't have any processing

capabilities of its own it also doesn't

have much memory or anything else okay

so it is literally

this is a dummy it's basically a screen

with a keyboard a mouse some sort of

input tool right and what it's doing is

simply displaying information on a

bigger better

server computer someplace else

all right

we also need something called a terminal

emulator placed onto this computer so

that it can emulate what's going on on

the server and communicate with it since

it doesn't have processing capabilities

or memory of its own now this is

different from what's called a client

a client has its own processor and

memory of its own but it accesses

network resources on other nodes other

servers and other clients

all right so it is um rather than a

server which serves up information the

client takes the information and uses it

now appear

is a network computer that provides its

own resources and services and computes

on its own the best thing about appear

is that it can act it is self-managed

self-contained and it is both a server

and a client

okay

so you can see how this works this

cloth this peer computer serves

information to this peer computer as a

client this computer can serve

information to this one as a client so

this is what we call peer-to-peer

networking it manages its own set of

local policies it has its own set of

users it is completely self-contained

and does not need a server to operate

unlike a client which does

all right

so

just to recap what we've talked about we

were we we defined what a network is and

how that's different slightly from a

computer network which is really what

the network plus exam covers

we describe the components of the

network

uh the adapter

the network operating system the devices

the media let's go ahead and write those

we had media

right which allowed the devices to

communicate

using a network adapter

communicated and managed by an operating

system we also defined a node and server

right the node is really any

um

sort of device that's on we have the end

point

and we also

have a redistribution

we Define and describe the network

backbone remember which is really fast

and the different variations of it which

if you recall included cereal which is

one after the other

hierarchical

also called distributed

then we looked at collapsed

and a more redundant form

parallel

finally we defined terminal client and

appear remember the terminal is a dummy

client accesses resources

on other computers

and appear both serves

and accesses

all right so now that we've covered some

of this basic terminology let's continue

on talking about the fundamentals of a

network And discussing more of what we

need to know in order to get into the

majority of this uh information on the

network plus exam

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thank you

Network fundamentals Network categories

and models

having discussed some of the basic

components of a network and having

established sort of a baseline of some

terminology that we all need to be

familiar with I now want to talk about

the different categories of networks and

as we begin to understand the

differences between these categories

we're also going to look at some of the

basic models that networks are placed

into depending on different

configurations and layouts

so our objectives in this module are

first to describe the characteristics of

a lan or what's called a local

area network now this is different from

a Wan or a wide area network you're

going to need to be familiar with both

of these terms and actually we're going

to see a few different types of lands

including uh man's

pans

cans

and uh none of these are what you think

these are all acronyms so a man is a

metropolitan or a municipal area network

uh pan is a personal area network can

campus area network etc etc and as you

can see from the name these these terms

are really

um amorphous so it really depends on

some subjective uh opinions as to what

these

types of networks really described but

anyway we're going to cover all of those

so you'll be prepared for them if if and

when you see them out in the field or on

the test we're also going to define the

difference between the internet

something that I'm sure you all have

heard of and then two other terms the

intranet and the extranat which are more

uh specific towards organizations and

sort of uh uh using internet

Technologies uh for a specific

organization we're then going to look at

uh the way networks basically are

organized we're going to look at

something called a centralized Network

which if you recall from the previous uh

video is going to involve a terminal and

a Mainframe and then we're going to look

at a client server Network which sort of

takes the pressure off of that Central

Mainframe and puts it onto a server with

a client and then finally we're going to

look at what a peer-to-peer network is

and again that is like where we have all

clients no servers so we're really

looking at a descending order of

centralization but at the same time

we're putting more power and resources

into the individual computer finally

because nothing is as simple as it seems

we're going to look at what's called a

mixed mode Network which is a

combination of sort of all of these and

that'll help us as we go forward

understand how an administrator of a

network something we'll also talk about

uh deals with these different types of

needs on their entire network

so let's first start talking about a

local area network a lan or a local area

network is a network that spans a small

area typically either a building like

your home or office or a floor of a much

larger building you might find this in

like a skyscraper so take the Empire

State Building for instance which is one

of the largest or tallest buildings in

New York or it used to be

um

every floor of the building might have a

different company using it so each one

of those has their own land or local

area network to keep them separated from

one another even though they might even

be using some of the same infrastructure

running into that building now in a land

the most commonly implemented technology

and something you've probably heard of

is something called ethernet and this

means that the communication path taken

utilizes uh cabling or short range

Wireless Technologies we're going to

talk about ethernet and and really what

it means because it's it's also not just

the hardware it really has to do with

how the data is being communicated in

Greater detail in an upcoming module now

in a local area network a connection uh

is leased by a service provider but it

isn't necessarily for the land to

function properly so this means I don't

need an outside sort of connection in

order for my land to work the reason I

might need a connection to the outside

from an internet service provider is

going to be thanks to a Wan or a wide

area network but let's talk really

quickly about land administrators the

people who are running these lands that

might help us understand them a little

clearer

now land administrators are like

jugglers they have to keep their eyes on

all of the components of their Network

at the same time hence the little GIF

over here they have to have there for a

broad range of versatile skills that

allow them to manage and maintain all

the different parts of their Network now

that's only within their domain and the

juggler also has to be mindful of each

of the objects in the air at the same

time or else they might lose track of

one or all of them like the juggler if

the land administrator loses track of

one part of their job it's likely the

entire network of moving components

could come quote unquote crashing to a

halt the land administrator therefore

has to have a strong working knowledge

of all the aspects of their Network now

the land administrator should be able to

handle tasks such as installation of

software and hardware

troubleshooting all components of the

network including the servers which

we'll talk about connectivity devices

and media and so on and so forth and not

to mention security for the network so

if that isn't enough one of their most

difficult tasking duties of the land

administrator is being responsible for

users and attending to their requests

and their requirements so

you can tell that the land administrator

really has to be able to do a lot and

we're gonna as we go through this course

you'll see more and more specifically of

what they have to do but let's talk

about a Wan a Wan or a wide area network

uh is a network that spans a larger

geographical area than a lan in most

cases uh the WAN is going to connect as

this picture demonstrates multiple lands

together and it might even utilize

long-range communication such as

satellite or radio frequency otherwise

known as RF

now one main factor that differentiates

a win or wide area network from a lan is

that it can enable users to connect to

one another from different physical

locations so whereas these are each

physically sort of uh isolated in some

ways you can tell the WAN connects all

of these lands together

okay now a Wan can be private where an

organization has complete control of

access to it resources and it's solely

responsible for everything that occurs

on that Network or a win can be public

and of course the world's largest Wan

is the internet

now we're going to talk more about the

internet in detail shortly but I just

want to point out that the biggest wide

area network we have is the WAN and

unlike the land which is geographically

isolated and can be controlled by a

relatively few number of people the WAN

has very different needs

now there are also different types of

lands that are out there now some of

these classifications

um we might get argument from certain

individuals just because this is sort of

open to some subjectivity but these are

covered on the examine which is the

reason I want to make sure we cover them

the first one that we've seen a few

times when we talked if you were here

for a plus is called a pan or a personal

area network a pan is two to three

computers connected together by cables

and a wireless pan or wpn is going to be

using Bluetooth or infrared Technologies

generally speaking when we are talking

about pans uh for purposes of the exam

we're really talking about Bluetooth now

I might consider pan a sort of local

area network but

for our sake we're just gonna group this

into wands right now but this could be

considered something a little different

okay so I'm just gonna sort of put

brackets around that and a w pan or a

wireless pan if we put that W in front

of it uh occurs when the computers are

connected together wirelessly but not

through an access point right so they're

connected literally uh to one another

thanks to the wireless technology but

there is no sort of Central Access Point

that they all connect to

now the next type is a can or a campus

area network and I'm assuming from the

name you can guess that this is a Wan

that spans the geographical area

comparable to like a school or a campus

or a business park such as Yahoo now

again some people might consider this a

land some might consider this a win but

for our sake we're just going to assume

that this is dealing with some sort of

Campus some sort of school some sort of

area that is contained all by one

organization so for instance if I had uh

four buildings all connected

uh and each of them has let's say four

floors

right there might be a lan on each floor

or in each building and then connecting

each land together is going to be this

can which is a sort of wide area network

but because the wide area network could

denote uh the internet and the cloud is

sort of the best descriptor of that we

want to call it something slightly

different now a man is a metropolitan or

it could also be a municipal

area network

and as the name implies It's relatively

the size of a city or a town or a

metropolitan area so if I have a

business that like the cam uh has

several buildings but the buildings are

now separated over the course of the

city as opposed to some in my own campus

then I'm probably going to use this

terminology again or a global area

network I think it's sort of redundant

but these are networks that go from

country to country or around uh

these are networks that go all the way

from country to country all the way

around the world they span the globe and

they're going to utilize Technologies uh

like satellite probably and the reason

we're going to call this uh again is

because generally speaking the global

area network again is all controlled by

one sort of company

as opposed to a Wan which as we just

discussed could include either all being

controlled by one company or

all being controlled by uh you know

disparate companies such as the internet

finally an En which is the only one that

breaks from this convention is called an

Enterprise Network it's a network that

includes usually aspects of both a Wan

and a lan and it's typically owned and

operated by a single entity or

organization just like a gan might be

now again these terms are very fluid and

flexible and depending on who you talk

to they'll call it different things so

you might I worked for a an organization

we never used the word man we always use

the word when talking about the network

that was deployed over the entire city

however certain individuals certain

organizations will call these different

things and the names might change as

well but it's important to have a firm

understanding of this just from a basic

you know definition standpoint but also

so that if you go out in the fields and

you hear people talking these different

terms you can talk the talk as well

now unlike land administrators whose

Duties are quite varied when

administrators are typically specialists

in their respective Fields so they're

responsible for more complex

infrastructures and as a result uh they

need to be more fluent in say routing

structures and troubleshooting different

difficult or different network issues

they're also responsible for say data

versus voice systems and when

administrators concentrate generally on

network oriented problems and not user

related issues like a land administrator

so with a a lan we're really going to

get these user-oriented tasks right

because they're dealing with the user on

a day-to-day basic a Wan administrator

is really not dealing with these or

they're dealing with sometimes what we

would refer to as the back end and in

some cases as well they're also going to

be a little more specialized in what

they do since what they're dealing with

is a lot more complex a lan

administrator can sort of be a jack of

all trades a wand administrator we want

to be a master of exactly what it is he

or she is dealing with

uh one of the other main duties of a Wan

administrator is the development and

implementation of certain scripts that

are going to automate certain Network

processes and they're also going to plan

for and test and push out upgrades and

updates to the infrastructure of the

network network wide whereas a land

administrator is going to do this on a

sort of local basis perhaps to the

computers in their Network so we can see

sort of how these are getting

differentiated here a Wan administrators

a lot more specialized and they're not

focused on user oriented

tasks they're looking at Network stuff

so you can see a Wan administrator again

dealing with the back end much more

specifically generally more Technical

and generally also a little bit more

training than a land administrator

now let's talk about the internet or the

World Wide Web which is a public wide

area network right it is the largest Wan

that we have and it essentially connects

every country on the planet in some ways

every computer on the planet it's used

for many different things including but

certainly not limited to sending and

receiving email initiating and

completing commercial and private

transactions uh commute communicating

and allowing people to connect to one

another that are sitting in the same

room or perhaps even on the other side

of the world the internet is really the

method by which everyone in the world

can communicate in one way or the other

and in some ways we can actually use it

to create our own virtual lands that are

private and we'll talk more about that

the other thing that's important to know

is every bit of data is stored somewhere

on a server typically in the form of a

web page and in order to access the data

data on the internet you're going to

have several different considerations

that are going to be made first of all

you need to have a web browser of some

sort

or you're gonna need to utilize a

certain generic protocol and have

something like uh so if we're talking a

web browser we're gonna need to use a

safari Internet Explorer Google Chrome

Firefox

Etc but they're all using HTTP which is

a specific protocol and it has a certain

port

which by the way is 80. we'll talk more

about those later in order to allow

communication to occur and this might be

different from say another form of

communication such as FTP or remoting in

and so on and secondly all devices that

want to connect to the internet must be

assigned we would call an IP address all

things on the internet due to the way it

works are governed by this IP or the

Internet Protocol we're going to revisit

this in a future module but IP

allows all of this to happen if it

wasn't 4ip we wouldn't have an internet

at least in the way we know it so again

the internet is this largest global wide

area network that we have in the world

and it's for use it's public and

everyone can use it if they you know

have a provider that gives them access

now this is different from an intranet

an intranet is a company's private

version of the Internet it's commonly

connected to the internet so that people

can uh connect even if they're not

locally at the same place physically but

the purpose of an intranet is to keep

your network or portions of your network

segregated from the unsecure and

possibly even dangerous internet so a

company might use an intranet for

security purposes or for confidentiality

if they have certain files and folders

they want to post up and the intranet

uses the same services and protocols as

the internet so the reason it shares

this name is intra enter to the

organization but it shares the same name

because it's using all of the same

services in other words IP HTTP you

still use a browser so on and so forth

so it's still accessed the same way you

would the internet through a browser and

a web page on the world wide web now all

of this is different from an Extranet as

the name implies

with an intranet your network is

completely secure from the internet

right you control who has access to your

network in every facet

but what if your company organization

needs to allow certain individuals to

have access to your network but you

don't want them to have access to all of

your network in this case we're going to

use something called an Extranet it

gives you the ability to Grant uh access

to specific portions of your network and

your Extranet so you can give access to

specific people typically vendors

suppliers individuals that might need

minimal or temporary access at the same

time your Extranet is restricting them

from having full access to the rest of

your network or your intranet so it's

really an extension of your intranet but

it's the part that is exterior look at

that extra

to your organization so again the

internet

is is a you know using a certain degree

of protocols and uh technologies that

allows anyone in the world to access

information the intranet is sort of a

private internet for your organization

and the Extranet is the part of that

intranet that you're going to let other

people from outside of your organization

have access to

now I just want to Define what a segment

is since we might see this term come up

a bit in the future a segment is a

portion of a Network that has linked

devices and that are separated by a

connectivity device such as a switch or

a router

all right so we haven't talked about

switches and routers yet but we're going

to and so what I mean is I might have a

lan

okay and

let's say that for simplicity's sake My

Lan is consisting of four computers all

connected through a central device

which we're going to call a switch

now remember if they weren't connecting

through that Central device this would

be called a pan a personal area network

but this is a lan has a central device

and let's say this Central device

and this I'm really simplifying it but

let's say it connects to another switch

and that other switch

has four computers connected to it now I

have different segments of my network

that uh I can join together in certain

information but I can also exclude them

from certain information in order to

allow for performance by segmenting we

allow communication between the nodes on

each segment to be uninhibited by the

traffic on other segments so I'm not

worried about uh if if computer a wants

to talk to computer C I don't need to

involve all of these guys I can just

allow them to talk directly and so what

it's doing is it's it's basically

keeping a lot of traffic from going over

this line

and therefore we're increasing speed

we're increasing throughput

and we're decreasing the amount of sort

of errors that can occur and we're

segmenting everything out to make it

easier to fix in the future as well

now let's talk about a network model

we've just talked about some Network

categories so now let's talk about the

different models that these are going to

fit into a network model

is a design uh specification if you will

that identifies the transmission path

that nodes on the network are going to

use in order to communicate it basically

determines whether the communication and

the processing

is centralized or distributed

so in a centralized Network this is

where we have our Mainframe

in our terminals

the host computer

this guy the Mainframe provides all of

the processing and all of the network

communication and the users that

interface with the host computer do so

through these Terminals and by using a

terminal emulator that's on the screen

centralized networks are highly

effective but the problem is they can be

a little costly to maintain because this

sucker right here needs to be so

powerful that what if I have instead of

just three computers what if I had a

thousand computers and what if this goes

out well now I'm in major issue I have a

major problem so this is why a lot of

times we use what's called a client

server model

the client server model it

in the client server model the server is

responsible

the server right here is responsible for

providing services like file sharing and

printer sharing and authentication

services and data storage and management

to these clients the main difference

between the centralized and the client

server model is that in this client

server Network the processing and the

resources can be allocated wherever they

are needed including on the client and

they can also be distributed whenever

necessary

and the end

nodes These Guys these clients can still

perform their own processing and end

user tasks without having to constantly

talk over to the server so if I need a

file for instance I can get that file do

the work on my computer and then I can

save it back to the server whereas here

on the centralized Mainframe terminal

setup all the work is actually done on

this major huge computer and here in the

terminal we're just sort of having a

portal to see what's going on now both

of these are different from what we call

a peer-to-peer Network we talked about

appear in the previous module but a

peer-to-peer Network which you might

also see as P2P or PTP

uh is a network in which each node on

the network is responsible for its own

Computing its own management its own

security its own storage its own

resource sharing like printers it's

completely decentralized and it's

commonly referred to as a work group

now this is sort of like if we were

going to make a reference to a political

metaphor this would be like communism

everyone works together equally and

everyone is responsible for their own

thing and then they can share that with

everyone else whereas in a client server

sort of uh

model we're dealing with say a democracy

in which you have a president or prime

minister someone who's going to make a

lot of the decisions but you are still

at Liberty to exercise a lot of your own

stuff and that's very different from

say a terminal Mainframe which is would

be equivalent to like a monarchy a

really strict here I should say

tyrannical monarchy in which everything

is decided for you and you make no

decisions on your own so one of the

problem with work groups is that user

accounts need to be replicated onto each

node so that if I want to get access to

this computer and I usually work on

computer y all of my username password

everything is going to be on there and

if it's not done if I don't sort of copy

everything over there's no way I can

gain access so this is the problem with

this model is each person's their own

but if x has wheat and I have corn

there's sort of no sharing that's

automatically set up we have to create

our own sort of share and then if

someone else says something I have to

share with them and so on and so forth

now we might sometimes mix these

together into what's called a mixed mode

Network and that's just like it sounds

it mixes aspects of two or more of the

different network models an example

might be a work group of computers

connected together via some sort of

short range Wireless while allowing

those computers to connect to a

Mainframe computer and using terminal

emulation

so alternative we might have a work

group and then a centralized server Etc

so we see we can see mixed mode networks

they're usually uh not as popular in

huge Enterprises because of the lack of

control

um except in certain specific instances

uh but we do see them and it's important

to know that just like in anything we

can mix and match

to however we want the the network to

work all right so now just to recap what

we've talked about we can now describe

and Define the characteristics of a lan

or a local area network as well as a Wan

or a wide area network and we also

talked about several of the uh different

types of lands or in some cases lands

including a can or campus area network a

man or municipal or metropolitan area

network a pan or personal area network

which is where the computers connect

directly to one another and then we

looked at a gan or a global area network

and then we also talked about en or an

Enterprise Network okay so these are all

uh different

acronyms that you need to learn for the

exam we also talked about uh an internet

intranet an Extranet remember the

internet is that World Wide Web right

the cloud the intranet is sort of using

this Cloud but in your company

and keeping it private that's my little

building and the Extranet is allowing

access

of your company private intranet to

perhaps

certain individuals from outside so it's

just a little bit of that

we also talked about a centralized

Network which is mostly

what we talk about when we deal with

terminals

and mainframes

and we'll sort of deal with this a

little bit too when we get into uh

virtualization when we talked about Thin

and Thick clients this is the idea of a

thin client on a network with a

a server of some sort or a

Mainframe I should say that is going to

do all the processing for it we also

looked at a client server Network which

is the majority of the types of networks

we see in Enterprise settings and a

peer-to-peer Network which we also call

a work group network in which every peer

is both a client and a server

responsible for its own

um

its own resources and so on I think we

use the metaphor that this might be like

uh

communism this might be like a client

server might be like sort of uh

democracy of some sort or a republic of

some sort and a centralized Network

would be more like I guess I should say

a democracy that is also republic since

um we do have officials and there's

someone above us right but a prime

minister a president sort of system and

then a centralized Network would be like

a tyranny

or a tyrannical Monarch I should say and

then we have a mixed mode Network which

is sort of a combination of uh the above

great

so we've talked now about uh some of the

basic terminology we've talked about the

models we've also talked about the

different categories so let's finish up

this basic Network fundamentals area by

talking about what are what are called

topologies how the networks are

physically set up and how they logically

communicate with one another

[Music]

thank you

Network fundamentals Network topologies

so now we're going to explain Network

topologies or uh the network layout both

physical and logical physical being how

it's physically connected and logical

being how the information is

communicated over that physical Network

and we're going to define the different

standard topologies that are in use for

today

so uh we're first going to Define

topology in general

then we're going to talk about physical

topology followed by logical topology

we're then going to explain a few of the

different types of topologies you need

to be familiar with for the exam

including a bus topology

star topology

a ring topology

a tree topology

and a mesh topology we're also going to

talk about a mixture of all of these

topologies that is called

a hybrid topology

these are the things you really want to

pay attention to these different names

and the names correspond directly to how

everything is set up so I don't think

it'll be too hard for you to remember or

to memorize

so as administrators regardless of the

specific role we're in we have to have a

complete understanding of the layout or

the arrangement of the network this

allows us to effectively design manage

and troubleshoot the networks for

performance and scalability a

scalability by the way I'm just going to

write that out here

because it is a term we'll see come up

over and over again is

um

how you can either make the network

larger or smaller depending on needs

certain topologies have characteristics

that allow us to have more efficient

communication while other topologies

focus more on immediate or faster

communication between certain devices so

understanding the topology of the

network allows us administrators to

troubleshoot the problems we're having

and then Implement Solutions easier and

more efficiently

so there are two types of topologies in

general and then there are specific

names for each of those topologies but

the two types are physical and logical

so uh let's take a look at the

characteristics that define a physical

topology and a logical topology

Google topology is the actual physical

layout of the devices so this is like

looking at the blueprint of our Network

this tells us how the devices are

actually physically connected to one

another it's also the shape of the

network and it gives us a sort of

picture to represent the layout or the

blueprint the physical topology ensures

that we administrators know and

understand how the physical media like

cables connect the devices to one

another

so a logical topology on the other hand

describes the how in other words it's

the pathway that data takes regardless

of how the network is physically laid

out this is how the data is actually

communicated over the physical

so the logical topology allows

administrators to troubleshoot and

fix the problems we're having with

communication between devices by

understanding the path that the data is

actually taking and we'll see some

pictures of this in just a second so

that will make this all a lot more clear

in a lot of cases the logical topology

could be very different from the

physical topology

so only because one logical topology is

for instance the star doesn't mean the

physical topology is also going to be a

star you can have a physical star and a

logical bus so that's why it's important

we understand but the difference between

logical and physical

so now that we've defined the difference

in a physical and a logical topology I

want to look at some of the different

connection methods that we use in these

topologies in the specific layouts both

for physical and logical uh but first

let's talk about how these things

connect because that's going to keep

coming back up

so the first type we have is called a

point-to-point connection this is a

direct connection between two nodes on

the network and remember when we're

talking nodes that could be two

computers

uh printers

Etc and remember we had endpoint nodes

and then we had redistribution nodes

so this these can either by the way be

wired or Wireless so an example of a

wireless point-to-point connection would

be for instance two nodes using an

infrared connection to communicate with

one another like your TV and your remote

control a wired point-to-point

connection on the other hand would be

two computers with network interface

cards or nics remember that term

okay connected directly together with

what's called a crossover cable so

there's nothing in between them right

they're connected directly to one

another using cables this might also be

the same thing we do if we connected two

computers together somehow using USB uh

cables although that's not really going

to happen very often in a network

setting the next type we have is called

a multi-point connection now as the name

implies we had point to point that's

like one to one

and then we have multi-point connections

which means that there are connections

between multiple nodes so there are two

or more endpoints connected together by

each multi-point Connection in other

words all transmissions are not private

because every node on the network can

detect the signal being transmitted

now there's also something called a

radiated connection and as the name

implies radiated this is specifically a

wireless connection so data is

transmitted wirelessly between devices

it's also by the way called a broadcast

connection uh although broadcast also

means something different as we will see

in just a minute

so some radiated connections would be

like Wi-Fi or wireless LAN and in some

cases even an infrared like your um a

remote control but the reason that

that's a point to point is it uh

infrared requires direct line of sight

whereas radiated connections that can be

either point to point or multi-point so

it sort of is uh it sort of involves all

of these different ones

all right now let's talk some about some

of the specific uh topologies the first

one I want to talk about is a physical

bus topology not a logical bust apology

okay so again this is the physical how

things are physically connected and what

this means is each node is arranged as

you can tell in a line so this is like

seats on a school bus everyone on the

bus can hear the transmission but the

message is only received by one specific

recipient so a bust topology is an

example of a multi-point connection

right because we have

it goes to all these different points

there are many points connected to it if

the message is for everyone on the bus

so I'm meaning I want to send this

message out to everyone that would be

called a broadcast connection broadcast

meaning it is intended and sent to every

single person on the bus or every node

uh on the network

If the message on the other hand is

meant to just go to one person or one

node we're going to call that unicast

uh finally if it's intended to go to

more than one recipient but not all of

them then we're looking at a multicast

Okay so unicast

as the name implies

means

one recipient

multicast

is two

or more

recipients

and then I'm just going to write this up

here broadcast as the name implies like

a television broadcast it goes to all

recipients on the network

it's important to understand the

difference in these types of messages we

have broadcast messages go out to

everyone unicast messages go out to one

recipient multicast to two or more but

different from broadcast because it's

not going to everyone or all of them the

way multicast works is that only uh the

stations or the nodes that have

subscribed to a message will receive it

so we could if we're using a TV sort of

example unicast would be like if you

have a direct line to your sort of

television provider multicast would be

like HP only those subscribing to the

specific uh cable network get access to

it broadcast is sort of any it's in the

air anyone can get it right so on a bust

apology like we're looking at right now

when the data is transmitted the signal

will bounce or reflect off of

the ends and so it's important

uh that when the signal bounces it's

gonna interrupt the transmission if

there's nothing there to stop that

bounce from occurring so to keep this

from happening we generally have

something called a terminator and it's

generally around 50 ohms I would

remember that for the exam because I do

see that pop up and what this does is it

really grounds the bus transmission or

the bus connections to reduce uh and it

reduces static electricity to keep this

Bounce from occurring that bounce occurs

then we're having all sorts of problems

start to occur in our Network now uh if

the way that these nodes are connected

as you can see are by these T connectors

and the reason they're called T

connectors is because they look like an

upside down t

now the downside to using a bus

connection are obviously these

terminators

and uh it's a little frustrating to sort

of connect these up but the upside to

using a bus technology uh topology

rather is that it's inexpensive and it's

relatively easy to implement

now this is different from a physical

star topology as you can see now instead

of a line everything is connected to

every other device using a central

connection device such as a switch

or a hub

in a physical start topology where a

switch is used what happens

is the node that's transmitting the data

to another node uh the switch actually

will

determine where that information needs

to go and send it only to the

node that is the intended recipient like

a unicast right

on the other hand a hub

is going to send the data out

to everyone and what's more like a

broadcast connection

now the uh and we'll talk more about

hubs and switches a little bit later

when we get to devices

the physical start topology it's very

common today and it's uh easy to

implement and maintain and it's much

more reliable than bust apologies

because if one node fails or one

connection to a node fails uh for

instance this one

then the rest of the network isn't

affected and a sort of client server

Arrangement each node is inherently not

aware of all the other nodes on the

network because the node only has a

connection

to this Central sort of host now the

negative aspect of this physical start

topology is we have what's called a

single point of failure here in this

connectivity device and if that fails

all of the other devices won't be able

to communicate so the benefit is now not

everyone has to get the message and it's

easier to uh it's sort of really cheap

and easy to implement it's also the most

popular because of any of these

connections go down I don't lose

connection to the whole thing unlike the

bus where if one of those connections

goes down obviously the connection can't

continue but the downside is that I now

have a single point of failure in this

Central device

now in a physical ring topology each

node is connected directly to its

upstream and its Downstream neighbors so

if we're looking at this device we'll

call it a those are the upstream and

downstream neighbors it's much like

water in an actual uh like River or

stream the flow of data in the physical

ring topology is unidirectional meaning

it only goes in One Direction

so the terms upstream and downstream are

only used in the ring topology

now here's the positive in using the

ring topology because data is received

and then re-transmitted

from node to node the transmission is

guaranteed to be strong and clear

because each node is acting as a sort of

like booster for the signal uh also

because the data can only be transmitted

unidirectionally in One Direction

there's no collisions that are going to

happen on the network in other words uh

if this guy can't send data that way and

then this guy's sending this data that

way and then they sort of cancel each

other out

so we're going to eliminate uh you know

where problems can occur and that's

going to help administrators determine

where an issue is occurring if they're

having an issue with the network now

negatively if one of these nodes goes

down on the network the entire network

potentially goes down as well and also

because data can only transmit in One

Direction there's a high potential for

data to take a longer time to reach its

destination because obviously if I want

to send data

to this guy but I'm unidirectional I

actually have to go here then here then

here whereas if I was using a star

topology I could reduce that by one A

variation by the way of this physical

ring topology that attempts to correct

some of the limitations is what's called

a dual ring topology

I'm just drawing that out

and a dual ranked apology gives a sort

of redundancy uh to the network by

having a second ring either on the

inside or the outside of the first ring

and it allows data to flow in the

opposite direction

so this can double the speed of the

network by sending data through the path

that's going to be the shortest between

nodes so if a wants to talk to C

or actually we'll call that b just

because of where it is and we'll call

this one c

um if a wants to talk to B it knows to

take the blue line as opposed to the red

line because the blue line is going to

get it there faster

so dual Rings also allow the network to

continue to operate if one of these goes

down which I think you could probably

see from this so if the outside ring

fails and the inside ring can actually

pick up the slack for the outside ring

a physical tree topology it's much like

its namesake as as you can see it's a

tree each branch of the tree

can only receive its signal for from its

parent node or its linked branch

right so all of these can only receive a

signal from

this guy the root node is what we call

the top portion of the network and it

does not have a parent so it is the root

just like a tree it's the roots it's

directly connected to each of the child

nodes that's what these would be called

by a point-to-point connection

now depending on how many levels you

have here and we can see we have three

levels here uh your tree topology is

gonna have is gonna dictate what the

what we call the branching factor is and

this might be a little beyond the scope

of the exam but I'm going to cover it

here anyway the higher the branching

Factor the longer it's going to take

from data to go from one node through

the network to the other because

obviously if this needs to talk to this

then right we're going to have

quite a bit of data that it has to go

through

a positive aspect of this entire

topology by the way is that because each

level is connected only to its parent

and its child nodes

it's very easy to troubleshoot where the

problems in the network occur because

obviously if you're having a problem

with you know this connection over here

you know that none of these have

anything to do with it

it's also the other benefit is it's

really scalable

remember that word because obviously if

I want to add another Network I can just

add it either here or I can add another

child here and then just sort of Branch

off there now negatively if the

connection should be interrupted or if a

node that's sort of a higher level and

the change should go down then all these

subordinate nodes would suffer so if the

connection between the root and their

children goes down we're going to be in

major issue because now none of these

can talk obviously if this computer goes

down

then none of these will be able to talk

to the rest of the network either so

this is a a problem with it it is a

variation by the way of the bus topology

so again if the backbone fails then

nothing else is going to work

now with a physical mesh topology each

node in the network is directly

connected to every other node on the

network so if we call this computer a

you can see it's connected to

B it's connected directly to

C and it's also connected directly to D

so for every computer on the network

it's for every node on the network

rather it's connected to every other

node

as a result because each connection is

similar to like a point-to-point network

uh communication between multiple nodes

can happen at the same time and so it's

very efficient highly reliable and has

minimal data congestion because B and D

can talk at the same time as a and C now

for the same reason these types of

topologies the mesh topologies are very

difficult to manage and to maintain

because each additional node that's

added uh requires you to connect other

you know every single other node to it

so if I wanted to add an e for instance

look at all of the connections I now

have to add to this already existing

Network so to alleviate some of the

negatives of this type of network

um it's uh

we sometimes have what's called a

partial mesh the partial mesh basically

means only specific nodes on the network

have to have direct links and this is

sort of where we're going to go when we

get into hybrid topologies

it's going to limit the number of

connections that are necessary

throughout the network so a partial mesh

topology would be useful if your network

is comprised of say like end nodes that

don't need a connection to all the other

nodes on the network but it still allows

high end devices to maintain the maximum

transfer rates and the maximum amount of

efficiency and reliability the

internet's major divisions are connected

to one another by a mesh topology so

we're really going to see this in sort

of large scale

implementations that need

High redundancy

and efficiency I should add

now a hybrid topology as we have we as

we've discussed utilizes uh aspects of

more than one type of individual

topology so hybrid topologies are

usually not created on purpose they're

usually actually created out of

necessity so topologies like this can

maintain uh are difficult rather to

maintain and to manage because each

segment in the hybrid topology might

have its own set of rules it needs to

Follows the technology is on the

different segments might not be the same

either so I might have a different type

type of Technology on this segment than

I do on this segment and I might and

then I have a different type of

Technology on this segment right here so

there are a few common types of star of

topologies that are in a hybrid sort of

breed that we come across this one's

called a star bus obviously because we

have stars here and then the stars are

connected by a bus connection notice

again the Terminators on either side

we also have what's called a a star of

stars hybrid you can see that each star

is connected by another star so it's not

only different topologies but when we

connect the topologies together uh sort

of in different ways that can be a

different hyper topology as well and

then another popular one is the star

ring topology so similar to bus except

there's no Terminators on the end

because everything connects together you

might also have a star dual ring

topology which I have seen uh all the

very infrequently by the way this one is

also called although I doubt you'll see

this

snowflake topology

now Network

Protocols are the controlling factor and

how all these topologies are going to

transmit data and depending on the

protocol data it might need to be

transmitted to all the nodes on the

network regardless of the physical

connection so this is why having a

logical topology is different from a

physical topology in other words the way

the data is transferred over the network

might be different than the way the

physical network is actually

connected so let me give an example with

this logical bus topology

okay data is received by all nodes

simultaneously even when the physical

setup is different so for example we're

using a logical bus topology with this

physical star so the central device is

receiving the transmission from let's

say the sending node which is this one

so let's say a is sending it out

and then it's passing it to each node in

succession in a continuous stream in

other words it's doing this

it's going down there and then it's

sending it here and then it's sending it

there and then it's sending it there and

then it's sending it there so you can

see what it's doing is although it's

connected in a star physically the nodes

are talking to one another as though

they are logical

now with a logical ring topology uh just

like with a physical ring the data is

only transmitted between its upstream

and its Downstream neighbors so even

though the star layout is physically

laid out in a certain way the data from

the transmitting devices is sent

in specific order

one to the next

now actually most ring

networks are physical Stars

right so every time the data is sent it

has to be sent to its up Downstream

neighbor

in succession like so

so it just goes in a circular route

we also have of course The Logical star

topology which can utilize a central

device

and it's going to pull each node to see

if it has the data to be transmitted so

basically it says hey uh do you have any

data you want to transmit okay do you

have any data you want to transmit all

right do you have any data oh you do

great then it'll transmit that data and

then come back around so the device

ensures that each node has an

opportunity to transmit but it also

governs how long that's going to happen

for and it's going to make sure that

there's not any

sort of problems or uh

collisions with the data

so just to recap what we just talked

about albeit a a 5 000 foot overview of

it we talked about topology which again

is like how the network is arranged that

Arrangement can either be physical

meaning how it is physically connected

or logical

we then talked about a bus topology the

bus topology meaning that it is

connected to each device one in sequence

we also need to terminate these with a

50 ohm

Terminator on either side and remember

we have a t connector that's connecting

them

we looked at a star topology

which means that these are all connected

through a central device a ring

topology

tree topology

which has branches

this might also be called by the way a

hierarchical

hierarchical

topology and so on and then a mesh

topology

which would be every device connected to

every other device

and then we also looked at a hybrid

of these

most commonly we're going to see a

physical star

with a logical ring

so it's important that as administrators

we have an understanding of how the

network is designed both physically and

logically in other words how the data

transmits over that physical stuff

[Music]

thank you

Network hardware and media bounded

Network media

having discussed some of the basic

terminology and some of the basic

Network setups I want to get into now

the hardware the media how this stuff

actually physically connects to one

another

so we're going to discuss the different

network hardware and media types in this

module

so the objectives that we're going to

cover are first defining Network media

and specifically bounded Network media

bounded Network media meaning the stuff

that you can hold bounded contained in

chords and wires unlike unbounded which

is Wireless we're then going to describe

the different types of copper media and

also explain the different types of STP

that's shielded twisted pair and UTP

unshielded twisted pair

then we'll describe the different types

of coaxial cable types and connectors

and finally describe fiber optic median

connectors fiber optics being that type

of

media that is that transmits data via

light and photons rather than

electricity over copper

after that I want to explain the 568 a b

and c standards which is how uh standard

UTP and STP is cabled on one end and on

the other so we can plug it in and

finally explain something called premise

wiring and structured cabling

so Network media is simply the method or

medium by which data will be transmitted

it's further classified based on the

hardware and Associated technology of

the media itself now there are both

wired and wireless Technologies

associated with network media so in this

one we're going to take a look at the

first one wired Network media which is

also characterized as bounded because it

is bounded by a chord

so bounded media is media that can be

physically held there are a few types of

bound media that we need to be familiar

with we're going to look at either

copper or Fiber now bounded Network

media is the basic and original form of

media and as administrators you're very

likely if not guaranteed at some point

to have to work with it in one form or

another

so having a solid understanding of the

different types of bounded media will

help you succeed in managing any type of

network whether it's at your home a

small office or even a very large

corporate win or wide area network so

the first type of bound Network media I

want to go over is copper media

copper media is the term used to

describe any media that uses copper

conductors as the method to transmit

data in the form of

electromagnetic energy so copper media

can come in many different forms there

are also many considerations that need

to be taken into account when choosing

between these different types of forms

such as a distance the speed

requirements of the network and of

course the cost

a lot of the time uh copper media was

going to be fitted with some sort of

shielding which also looks like braided

metal wires or sometimes it looks like a

metallic foil like you buy at the

grocery store but it is a little

different the shielding on the outside

helps the cable prevent or helps prevent

the cable from being uh subjected to

what's called electromagnetic

interference or Emi and of course if I

allow Emi or electromagnetic

interference to get into the copper

within the cable then that's going to

disrupt the sort of data that's going on

inside of it now there are two uh

different types of very common copper

media that I want to go off uh uh

specifically of coaxial or coax as shown

here and twisted pair

now twisted pair table is one of the

most common cable types that you need to

be familiar with depending on the

specification of the cable and the type

of twisted pair cable being used there's

going to be anywhere from two to a

hundred pairs or more

now the pairs are color coded so the

technicians know how to recable the

cables on either end and it ensures that

certain wiring standards and schemes are

maintained in case another technician

was to come in and start or end the work

that you've already begun

now all twisted pair cables are

basically the same however it's how they

are terminated that makes the biggest

difference meaning how the end points so

what happens at the end points now there

are two typical types of standards that

we need to be aware of these are uh

t568 a and t568b so we're going to take

a look at these right now

now 568a it's less common than 568b

today in today's networks but it's still

necessary for you to know and you need

to understand the difference between the

two of these uh and it'll also help you

in case you ever wanted to make a cable

at home

568 a is wired in this way green white

green

orange white

blue

White

Orange

brown white brown

now the only difference between the 568

a cabling standard and 568b is that the

first two pins one and two are swapped

with pins three and six that means that

the orange colored wires are swapped

with the green colored wires so then in

568b we see a wiring of orange white

orange green white blue

blue white green

brown white and brown

now

the reason you need to know both of

those is because of something called

crossover cables which we'll talk about

by switching those uh pins around it

switches the data and how it's sent and

we'll talk about the purpose of that a

little bit later on

but for now let's talk about something

called STP or shielded twisted pair

cabling which is a cable type that

contains pairs of copper strands like we

just looked at orange white and orange

for instance being a pair that are

twisted together and wrapped with a

metal sheath or a kind of foil that

decreases the cable susceptibility as

we've already mentioned to Emi now

because it's wrapped in its metal it

makes the cable much more expensive than

its counterpart UTP or unshielded

twisted pair and it can make it more

difficult therefore to manage or work

with now although it has the shielding

to prevent it from Emi it doesn't mean

the cable is prevented completely from

any sort of susceptibility it just

reduces it I also want to mention the

reason that we have that twisted pair

each pair of cables for instance orange

and white orange are twisted together is

to reduce what we call crosstalk meaning

that so that the data doesn't sort of

jump between the two cables this was

something that was actually discovered

way back when when Edison was dealing

with electricity now UTP or unshielded

twisted pair cabling does not have that

metal shielding around the Twisted pairs

this is the only difference now this

makes the cable much more susceptible to

Emi than sdp however it's so inexpensive

and so much easier to install and

maneuver with and in most instances a

lot of folks don't need the extra Emi

protection so it's why it's one of the

most common

now there are several specific

implementations of sdp and UDP and each

one has different standards uh and

characteristics and speeds and so on so

let's take a look at those in a little

more depth right now

you may have heard of the or seen the

terms CAT5 or category five or Cat6 or

something similar to this before let's

take a look at what these terms mean and

what the specifications are regarding

them because you'll need to know that

for the exam

cat simply stands for category there are

both STP and UTP versions of these

category cables that stand if you recall

that's shielded and unshielded and the

first category of cable is as you'd

imagine category one cable now we don't

really see this in the field anymore

it's been superseded by the following

categories cabling and but its original

purpose was for voice I wouldn't worry

about memorizing that one

type 2 or Category 2 is rarely used

today uh only in something called token

based networks which we'll talk more

about in the future but again it's not

very common you're not really going to

see it uh very much at all

now Category 3 or ethernet which is

different from the current ethernet but

this was the first category established

by an organization called Tia eia this

is the Telecommunications industry

Association Electronics Industries

Alliance don't worry about memorizing

that but in today's networks category

three or cat 3 is used almost completely

for voice Transmissions because it has a

limited transfer speed of 10 megabits

per second and a 16 megahertz bandwidth

so a lot of

telephone K old telephone cableing is

cat 3. cat4 uh just like cat 2 it's not

used anymore not even worth really

spending time in now when we get to CAT5

this is sort of where we start really

getting to Modern Day stuff Cat 5

cabling which is also called Fast

ethernet provides performance of signals

up to around 100 megabits per second

important that you know this the maximum

distance for CAT5 cabling is 100 meters

or 328 feet

now CAT5 e is the specification that

superseded CAT5 and it addressed some of

the weaknesses including uh crosstalk

prevent prevention uh and other

specifications in the like like CAT5 the

maximum cable length of Cat5e is also

100 meters the bandwidth is also the

same at 100 megahertz but it's said that

data data rates can get up to about 350

megabits per second uh although

sometimes an application that's not

exactly what we see

Cat6 is a standard uh that increased the

transmission speeds quite a bit it's

what's called gigabit Ethernet because

it's rated for data rates of about one

gigabit per second so we're going from

again with 10 cat 3 from 10 Cat 5 100

Cat5e 350 theoretical and now we're at

1000 megabits per second or one gigabit

per second

the signal limb rate also of CAT5 Cat6

rather is tested at 250 megahertz uh but

it's guaranteed at a 200.

there was also another one after this

called cat6a which was also known as

augmented category six and it had a

rating of a little bit more than a one

gigabit but uh many people said that

they can actually get to 10 gigabits and

uh uh it's megahertz or frequency was

also Higher by the way I wouldn't worry

about any of the frequencies I'm just

throwing those in there so that you know

them what you really want to worry about

is the data transfer speed

a cat 7 which is one of the newest

implementations uh it's not even fully

recognized yet by Tia eia it's

um also gigabit Ethernet and it

supposedly supports a signaling rate of

one gigahertz and has a potential for

over 10 gigabits per second so you can

see where we're we want to go there but

at the same time Wireless technology or

unbounded technology has taken us to a

point where we might not need to spend

as much time on some of the bounded

media

so

now that we've seen all of these

individually

let's take a look at an easier breakdown

of the specifics of all of these

so as we can see here each of these cat

standards has a maximum cable length of

100 meters for standard use and the

frequencies and maximum data ranges go

up with each of the standards as well in

most cases when you're looking at the

physical cable the exact specification

is typically printed on the cable itself

helping technicians ensure that the same

standard is going to be used throughout

the organization

now while Cat 5 through 7 cables are

very similar because they all use the

RJ45 connector which is the connector at

the end that plugs into your network

card or into a port uh should a

technician install a Cat5e cable and a

cat 6 or higher Network the Network's

still probably going to function

correctly but the Network's only going

to operate

at the uh maximum speed of the lowest

standard so if everyone else in the

network has Cat6 and you install a Cat5e

cable then you're limited now to the

Cat5e

um specifications

now here's a picture of an RJ45

connector I want you to note there are

eight pins which means there are uh four

Twisted Pairs and next here's a picture

of an rj11 which is used for phone lines

and notice that this one has four pins

so that's two Twisted Pairs and it's

also much smaller than RJ45 this is

what's used in what's called pots plain

old telephone system or pstn the public

switched telephone Network

all right now moving on uh past cats uh

and and twisted pair let's talk about

coaxial cabling uh it gets its name by

the way from uh this is sort of a fun

fact common geometric access or common

core because the shielding and the

conductor share the same Center

or axis as the name implies in common

geometric access or axis

surrounding the single copper core is a

non-conducive meaning that it's not

going to conduct electricity insulated

coating which is typically uh some sort

of dielectric insulator separating the

core from the shielding

the next layer after that is braided

metal shielding and this could be either

copper or steel sometimes it's a mesh of

multiple Metals depends on the

manufacturer the purpose of this

shielding just as it was with the

twisted pair is to protect the cable

from Emi or electromagnetic interference

it also allows the cable to be grounded

and acts as sort of a drain when there

is noise on the line we'll talk about

noise in just a few minutes and also

ways to prevent it

the final layer on the coaxial cable as

you can see is this outer sheathing or a

plastic insulating jacket

which just sort of keeps everything

protected from the elements

now there have been several types of

coaxial cables used in networks over the

past few years uh here's a breakdown of

what you should be familiar with the

first is what's called an

rg58u it was used for ethernet

networking actually if you see old

network cards you'll actually see a a

coaxial cable on them and it has a solid

core and requires a 50 Ohm resistor it's

about five millimeters thick this is

different from the stuff that brings

cable into your home and if you remember

50 ohm resistor that is what was used on

a bust apology and that's why where we

actually used most of these was on a bus

topology now the

rg58au is slightly different in that

instead of having a solid cord it has

what's called a stranded core which

means there are multiple strands or

cores at its Center as opposed to one

solid one

next and this one might be a little more

we're going to get a little more into

sums that you've probably seen is What's

called the rg8 standard it was also used

for ethernet networking but it's not

seen very frequently today

um because it's typically was used for

backbone wiring and it's been which has

largely been sort of superseded by fiber

optics

finally we have rg9 uh coaxial cables

which are used with cable TV cable modem

installations and so on it's about 10

millimeters thick which is twice the

thickness of the original RG58

now we're getting into some others here

that I wouldn't worry too much about for

um the test but I just want to go over

them since we're covering these anyway

we have something called rg62 cabling

which is utilized for uh something

called an arcnet protocol uh networking

it was a lan protocol uh commonly used

in what was called microprocessing and

then we have an rg59 cable which was

used with low power which is used rather

with low power video and receivers uh

and it had also resistors and it was

about six millimeters thick the RG6

cabling which is greatly preferred by

the way over rg59

uh because it's more common is utilized

for cable television signal routing and

also requires

uh 75 ohm resistors

the term by the way thin net is in

reference to ethernet networking that

uses the rg58u or Au cabling these thin

net cables coaxial and the reason

they're called thin is because that thin

five millimeter

uh coaxial cable can be up to 185 meters

in length which is quite different from

the 100 meters we got with ethernet uh

Twisted fare

Network segments that utilized coaxial

cabling have to be terminated at the

ends like we've talked about to provide

that signal Bounce from occurring

they're terminated by installing that

resistor that matches impedance uh that

matches the impedance of the cable on

the ends so as we've mentioned some of

these are 50 ohms 60 Ohms on a

a typical bus topology Network we're

looking at 50 ohms

now here's a visual of what the most

common coaxial connectors are first we

have a picture of a BNC connector with

different types of resistors attached if

we look closely at the top connector you

can see the small needle at the center

is just slightly bigger than the 50 ohm

on the bottom this is important uh in

case you have a 75 ohm which is plugged

into a 50 ohm because there's going to

be a potential of damaging the connector

that's being received

now this next picture is a shot of a t

connector and a Terminator remember we

talked about these when we were talking

about bust apologies and when purchasing

these you want to make sure you check

that they're properly rated

because uh you know every manufacturer

has different color schemes and

different types of uh ways of

categorizing their terminators

now moving away from

copper cabling which is what twisted

pair and coaxial is let's look at fiber

optic cabling which is cable that uses

pulses of light sent down glass or

plastic core

the components in fiber optic cables

start out from the center working their

way out so the inner strengthening Rod

gives the cable its most most of its

rigidity otherwise we would just sort of

crack this stuff because it's very thin

so we have something that's going to

strengthen the rod and then the outside

of the inner strengthening Rod there is

filler compound in between the strands

of cable

at the center of these individual

strands is the fiber core which is

between 5 and 100 microns in a diameter

and I don't know if you are familiar

with that term Micron but that is very

small that's roughly

um slightly larger than like I think a

human hair so just to give you a context

there

surrounding the glass or the core which

might be made of plastic as well is what

we call Core cladding which is

responsible for trapping the light in

the core and reflecting it in a

particular way depending on the cable

mode and on the outside of the course

cladding there's a buffer that is color

coded so a technician knows which strand

they're working on

next we have strengthening fibers that

are typically made from very strong

material and finally on the outside is

an outer protective layer called the

jacket the transmission method again

utilizes pulses of light

these lights can come from LEDs or light

emitting diodes in cases where there is

a slower Network or in network with a

much faster connection we might even

have a laser

now there are different types of fiber

modes and as an as a network plus

administrator you need to be familiar

with the different methods of

transmission for each

in single mode fiber only one single

beam of light passes through the core

now a bandwidth of up to about 30

megahertz megahertz can be reached and

the signal is modulated by intensity to

transmit data so the intensity

determines the data

with the next thing we look at is Step

index multi-mode fiber the core of the

fiber and the clouding surrounded it

surrounding it rather have different

indices by the way if you're not

familiar with that word that's the

plural for index of refraction if that's

a little confusing that means that they

have different densities which changes

the speed and velocity of the light that

travels through the medium so when the

velocity changes it's called the step

down this is why we have step index

finally we have something called graded

index multi-mode fiber this has a core

glass a glass core rather that itself

has differences in variations in the

form and that allows for a large amount

of bandwidth that reaches up to about

two gigahertz

now the thing I want you to remember

most about single mode versus multi-mode

I wouldn't worry so much about the

graded index and step index but what you

do want to remember is that single mode

is good for longer distances but not as

high transfer speeds multi-mode is good

for short distances and uh higher

transfer speeds think about it this way

if I have a very large bus I'm going to

be able to carry more people uh in a in

a shorter distance if I have a sports

car I might be able to carry one person

or two people but we'll go a lot faster

so you can think about it that way

now St connectors or straight tip

connectors are one of the most common

you're going to see today they look very

similar to the coaxial BNC connector and

uh one way you can remember it is you

have to twist them on and I think about

that t for Twist the SC or otherwise

known as a subscriber connector is also

one of the most common connectors so you

want to recognize that one as well

we also have something called the LC

connector which looks almost like an

RJ45 type connector and it snaps in

place it's also about half the size of

an st and SC connector

I also want to show you some of the

other connectors that are listed on the

outline although I don't see them much

on the exam uh an mtrj or mechanical

transfer register Jack which is also

called a fiber Jack it's it's again just

like the same size as an RJ45 and it's

usually used to connect two strands of

fiber together

there's also a few other connectors uh

FC which is face contact uh it's used in

industrial environments uh it has a

different Center that sort of gives it

more strength there's also something in

this this you will see is called fuddy

or Fiber distributed data interface

which can also be called uh mic or SMA

or sub miniature assembly all these

different names it's an older connector

and it's uh one of the original

connectors that was used

now because of the different

technologies that are available for

networks today it may become necessary

to go from one type of medium to the

other in some of these cases we have to

utilize what's called a media converter

here are a couple common media

converters you may have come across in

certain networking environments

now there are media converters that

convert signals on fiber to coaxial

cable when you're converting

um

multi-mode fiber into ethernet in order

to extend the ethernet network over a

fiber backbone we also have similar to

multi-mode fiber there are also

converters that go from single mode

fiber to ethernet as well which is for

the same purpose generally speaking

we're going to see more multi-mode in

the backbone environment because it's a

shorter distance high high throughput

lastly there's also something a single

mode which converts to multi-mode fiber

these connectors are generally used to

extend the range of multi-mode signals

now the Tia eia which we've already

mentioned the organization

telecommunications industry Association

electronic Industries Association uh

created standards for all this cabling

that covers the proper implementation

design and maintenance to ensure that

there's a certain level of performance

that's met and that's also going to

ensure that if someone else comes into

your environment they know what they're

getting themselves into now there's six

uh the standard is comprised into six

different categories and it's important

that you actually know these for the

exam this by the way is called

structured cabling

so first we have something called

entrance facilities and this covers the

entrance of the Communication Service

into the building and this includes

What's called the demarcation point

the demarcation point is that point at

which the responsibility of the network

changes from you to your ISP or from

your isptu or your company it also

contains the backbone connections as

well

next we have the backbone wiring which

is the wiring connection that goes from

the communications closet to the

equipment rooms so the characteristic of

this wiring is going to depend on the

type of media chosen such as copper or

Fiber but nonetheless we need to make

sure it's it's very sturdy and also very

fast

the equipment room now uh so we've gone

from uh dmarc to Backbone or uh we've

gone from entrance facility or dmarc to

Backbone to equipment the equipment room

is the point of termination for the

backbone wiring it's also called the MCC

or the main cross contact and this can

also be considered what I've seen it

more considered on the network plus exam

the MDF or the main distribution frame

we're going to talk more about this

shortly

the next portion of structured cabling

are the Telecommunications closets so

these are contain the connection

equipment for any of the nearby

workstations as well as the connections

between any Communications that

cross-connect

we also have something called horizontal

wiring which is the cable and that goes

between workstations and the

Telecommunications closet and this is

typically in the wall in the ceiling

finally

we have the work area which is

everything coming from the wall outlet

to the workstation so this is the face

plate connectors wiring and so on so you

can see that we're going from the sort

of main point in our building that

entrance where the D mark happens where

the ISP the internet comes into our

building all the way down to the

workstation or the user

the Tia eia has also set out a

specification of standards that line out

minimum performance levels for Network

media in uh commercial environments now

these standards are 568 a b and c we saw

earlier the t568 A and B which were the

standards for uh cabling colored Twisted

Pairs and how they should be arranged

and terminated but there are also some

other specific attributes that you need

to be aware of

the 568a specification is an older

standard it's governed uh it governed

data voice video and commercial

buildings and it's basically been

outdated and superseded nowadays by 568a

sorry B and C standards the B

specification now is an earlier standard

still in use quite frequently that

defines minimum performance levels for

cabling including twisted pair

performance minimums uh shielded Twisted

paramums fiber optic standards and Etc

portions of this are now Obsolete and

have been replaced by 568c the 568c

standard

which is the current specification

that's set out designates minimums for

optimizing Network media performance in

commercial buildings currently it

specifies cat 6A as the media type that

is recommended so again the 568 A and B

the T5 to 68 A and B that we saw earlier

those are how everything is cabled those

fall under the umbrella of the more

General 568 a b and c standards which

speak more to Performance

now while the Tia and the eia have

established uh standards for structured

cabling

premise wiring uh

the terms that we're going to use are

industry-wide so although there might be

these standards the terms you're going

to see over and over again

hierarchical cabling is recognized and

used which is what we're talking about

when we talk about premise wiring

everywhere

it's a telecommunications design

tradition that basically allows for main

cross connects or MCCS to be connected

to what are called iccs or intermediate

cross connects in a star topology with

horizontal cross connects in most cases

you're probably going to see the terms

wiring closet MDF or main distribution

frame and IDF or intermediate

distribution frame instead of MCC and

ICC however they're both used

interchangeably so I just want to take a

look at some of the components that make

up this premise wiring right now

the patch panel is the connection point

for drop cables and patch cables they're

connected to the patch panel via the

RJ45 connectors that we saw with twisted

pair now you might find a patch cable

with a single row of connections or one

with a dozen or more rows now a drop

cable what I just mentioned is the cable

that goes from the workstation and the

network devices to the wall

a patch cable is a cable that is

connected to the patch panel and

connects two drop cables this cable

might be either a normal straight

through cable or a crossover cable which

is something I mentioned earlier that

crossover cable has one end that has the

568a wiring and the other end that has

568 B wiring this is in order to connect

two like devices such as computers or

switches directly to each other remember

the pin out on these is different

because the one and two pins are

switched on one end with the three and

six pins so this allows data to go

directly between two devices a lot of

devices nowadays however don't require

the crossover cable uh because they have

an auto sort of sensing feature within

them now a patch panel and patch cables

are located in wiring closets

the IDF is the communications connection

point or cable rack that connects all

the workstations to the MDF or the main

distribution frame the main distribution

frame MDF is the main connection point

or cable rack that distributes cables

from itself to all the other idfs now

there's only going to be one MDF but

there can be many idfs the wiring closet

is a room where the patch panels are

installed and the wiring runs through it

too

so here we have a building where we have

an MDF on the bottom floor and an IDF on

each of the floors above the connections

going from the idfs through the walls go

to the workstations then there is a

connection that's typically much faster

than the rest of the network that goes

between the idfs and the MDF

when installing Cable in a building

there are fire code requirements that

have to be met

specifically when you're running cable

and air handling spaces which are like

under floors and in walls most of the

fire codes require a specific cable

PVC cabling which is the typically

standard network cable that's fairly

inexpensive and easy to work with allows

allows fire to travel through the cable

if it berms and then it releases these

poisonous and noxious fumes so as a

result plenum grade cabling which is

part of the uh plenum or a plenum space

is part of a building that is used for

air circulation and HVAC systems and so

on by providing Pathways either that are

heated conditioned or have return

airflows

space between the structural floor and

the dropped ceiling or under a raised

floor is what's called plenum so we have

some special cabling called plenum

cabling this is jacketing that's wrapped

around the wires very tightly and it

prevents fire from moving through it

therefore it's not going to put off

those noxious and poisonous fumes it

also makes the cable a lot more

expensive and it can be a lot difficult

a lot more difficult to work with at

times however it is required by fire

code that if you're running cabling in

between these spaces where there is no

sort of

sprinkler system to put out the fire

that you use plenum grade cabling that's

important all right so now let's go over

what we learned first we defined Network

media as well as what bounded media is

we're going to talk about unbounded

media a little bit later we also

describe the different types of copper

media including the different types of

Stan shielded twisted pair and

unshielded twisted pair and the

difference between those remember

shielded it protects from Emi unshielded

does not and we discussed a few of the

standards that are set by the Tia eia

including 568 a b and c and remember

that's we also have the 568 A and B

wiring requirements which fall under

these we also looked at the different

connector types not only for the twisted

pair which is that RJ45 but for coaxial

like the BNC and fiber such as St or SC

and we looked at structured cabling and

premise wiring where we also talked

about the differences and this is

important between PVC cabling

and plenum grade cabling

[Music]

welcome to module 2 lesson 1A straight

through crossover and rollover cables

we've actually covered some of this

already in earlier lessons but what I've

done is added upgrades for the new exam

syllabus so consider some of it a

refresher and um some of the new

material

so we're still under Network Hardware

media bounded Network media

a few of the objectives

looking at modular connectors the

t568a and B wiring schemes MDI and mdix

straight through cables

crossover cable and then Auto

mdix which is a bit of a mouthful

and uh another cable you'll be using

regularly as a network engineer which is

a rollover cable

they've got different names actually

they can be called console cables if

you're working in the Cisco side of

things we tend to call them rollover

cables or flat cables

but I'm sure you'll find out wherever

you end up working what uh

what they're called so modular

connectors

a type of electrical Electric electrical

connector that's commonly used in the

following systems we'll see these in a

telephone systems data networks which is

what we're more interested in as Network

engineers

low speed serial connections can also

use them

and now by the following names RJ which

is short for registered Jack

modular phone jack stroke plug

uh Western Jack stroke plug

just go back there you can see the port

which is the interface that the module

modular connector goes into and then the

physical layer which will specify um a

whole bunch of things like the voltage

on the wire and how many wires and or

teach wire is used for some of them are

unused and um as the connections get uh

quicker

and the engine is worked out how to use

spare air wires to increase speed which

you'll see in a bit the male modular

connector is known as a plug

uh basically the cable

um is terminated inside here normally

you do buy these however

um if you become a cabling engineer

you can have your own tools to make your

own network cables I did it for a while

I can't say it was particularly

um a lot of fun

but it did pay pretty well

a female modular connector is known as a

Jack or socket

used on fixed locations

um such as on equipment

uh example of the module modular

connector is the 8 p8c connector uh I

think Josh may have referred to that

elsewhere

but here we go here's a an image of one

uh using ethernet computer network that

uses the twisted pair cables for

connection which is pretty much every

Network now unless you went into some

old basement

um or some odd unit somewhere

commonly referred to as RJ45 it

resembles the connectors you'd have on

many phones we have at home which uses

an RJ 11

telephone cables But as time goes on

these will all be changing and I think a

lot of people don't really even use

their home phones much anymore

uh has nothing to do with the actual

RJ45 standard

looking at the um t568 A and B wiring

schemes

these are the specifications in more

detail it's a four pair 100 ohm and

shielded twisted their cable

and

usually terminated into an a position

modular Jack

now there's two wiring schemes five six

eight a five six eight B

this defines the pin out and the Order

of the connections and this is very

important we can't just connect any

color cable

um inside and attach them to any of the

pins on them on the end there has to be

a specific order depending on what we're

trying to achieve

you can obviously buy the cable it comes

off um big rolls it could be a few

hundred meters long and it's twisted

into one two three four pairs there

and they can be just untwisted slightly

at the end and then the you can see the

blue shielding there is normally

inserted just enough so it um catches

inside the Jack and then you've got a

crimping tool which squeezes it onto the

plastic connector on the end

now we as I said we need to know which

wire of the cable connects to which pin

and which wiring standards we use the um

t568 A and B standards govern the

assignments of the wires so it says

which wires go where

now here's a graphic you can see and the

pairs are put together with similar

colors and then the specific colors

allocated for each pin going from one to

eight so

um white and green green white and

orange

and blue white and blue orange

white and brown and then Brown

you can see different pins on the right

because we've got a different standard

yes and I've put on here which one's

which

so there's an interchange of green and

orange wire pairs between the two

different standards

now I'll come to horizontal cables in a

minute because

[Music]

um

you don't actually hear this

um term very often in Internet working

and I hadn't heard of it for um until I

come to put all the information together

for the presentation but it's a

recognized name even though it isn't

used very often

so the um 568b pin app became model used

because it matched the older at T their

pin outs and you can see the standard

there widely used a new TP Cable in at

the time and the infrastructure

regulations and numbers were published

just for your information you can

research in your own time if you want

but you can see a horizontal cabling in

action here generally it's the cabling

that runs between all the user devices

the patch panels and the network

switches now however you've got your

network designs you'll normally group

the switches together with what's known

as backbone cabling

so that's it in um image format there's

a definition which I got from Wikipedia

it can be the inside wiring or plenum

Cable in connects your telecoms rooms to

individual Outlets or work areas on the

floor usually Through the Wire ways so

this is the part of the cabling that you

would normally

um be concerned with as a network

engineer and then um the core Cable in

the backbone cabling May well be done by

a cabling company it's not something

that you would normally get involved in

again it depends every networks a bit

different

and moving on to MDI and MDI X

and

devices on ethernet networks use two

types of Hardware interfaces which I've

already mentioned here the MDI it all

stands for media and medium dependent

interface

so Hardware interface that establishes

the direct physical and electrical

connection with a UTP cable this is the

traditional port on the back of a

computer's network interface card

an MDR device is a device with an MDI

Port which kind of goes without saying I

guess a computer or laptop

um and this is a reference for

specifications really I mean in all the

years of networking I've never referred

to a device as an MDI device

and tend to discuss it more when we were

using Hobs

um in the earlier days of networking the

mdix stands for um the MDI but with a

crossover

this is a crossover of the

um medium dependent interface I'll show

it up an image actually in a moment the

thoughts of the devices that provide

connectivity such as a switcher hover

setup as a MDI with the crossover

foreign

so examples of the devices are switches

or routers and I'll put in an image here

to give you more

um

a frame of reference you can see here

it's the front of an old fashioned

Netgear maybe they don't even sell him

anymore

um Hub and you can see to the right

there's a little black switch with a

little line that connects to the number

four

now however you press that button it

will act as an MDI or an mdix interface

now if you wanted to connect that number

four port to a PC

you would leave it running in normal

um mode you might be able to see the

actual word normal it's a bit blurry

this image so this is MDI and they're

put normal because um You probably

wouldn't be a network engineer using it

at home or small office

um the mdix they've designated as an

Uplink that means you would connect it

to another hub

and so the it would change the way it

connect and communicates using the

different pin outs and it would act as

if um you you're using a crossover cable

which we'll come to later

so this is basically what I've said it's

going to um using the button you would

um designate whether it's going to act

as an MDI or an MDI X interface

um this all basically changes how we use

our transmit which is designated as TX

and I'll receive which is designated as

RX on the different wires and that's

saying what that setting would do

straight through cable the easiest way

to think about straight through cable is

um using dissimilar devices for example

a um computer to a switch port a router

to a switch

and here's some examples also known as a

patch cable in case anyone asks you to

check a patch cable or get get them a

patch cable

I've mentioned UTP UTP cables they're

used in the modern ethernet Networks

and you can't directly connect unless

you stay in the obvious I think you

can't directly connect these wires to a

computer's network interface card

um if you want to be picky I suppose you

could if you had a soldering iron and

individually sold at each wire but that

would just be a little bit of a

desperation not somebody that doesn't

really need to unplug

so both ends are terminated with the

8phc connectors

and you can see the two wiring types

here using that AP AC connectors

now the pins and the wire assignments

are the same on both ends so we know

this is a straight through cable or a

patch cable the numbers match

and well that's just a number into the

pins the colors of the different wires

inside match and that's you could tell

you would hold the cable together if you

didn't know if you wanted to see if it

was the right kind of cable hold it up

look at it and check that all the wire

colors match

now the worrying standards for the RJ45

is the um 568 amb they specify how to

wire the actual connector over an

Ethernet Network technically you could

choose any order of colors you like if

you were making your own cables

and as long as it matched the other side

then it would all work because the

cables inside the the eight little wires

are all exactly the same

but um you wouldn't obviously be

following the standards so maybe you

could do it for your home network if you

wanted to make your own cables but

certainly not recommended for commercial

Networks

so only one of the following standards

used for terminating ends of the UTP you

could choose either

and but I think I mentioned earlier the

recommendations for the horizontal

cables

so the example of a straight through

cable is computer or a server connecting

into a switch port

I've already mentioned that you wouldn't

use both standards on them on your cable

straight through cables are used when

connecting to an MDR device or an ndi

device to an mdix device

and again we've seen this this is just

zoomed in and giving you a better and

detailed image of the cable type here

if it's straight through UTB cable is

terminated on both sides using the type

a wiring

then the a color scheme and should be

so I'll say that again then the color

scheme and the pin out the order of the

connections will be shown in the diagram

so this is the a standard and you do it

a few times

um for a few days and then you probably

have it in your memory of what all data

put the wires in again if it was you

making the cables which um

wouldn't only really happen if you were

um

a cabling engineer for a very large

Network

and there's the pin outs and the colors

in more detail you can see the tip

transmit and the um receive indications

on either end there

so when a computer uses pins one and two

I have a pair of wise to transmit the

switch will receive those data on the

same pins

when I sit when a switch transmits the

data using pins three and six on a

different pair of wires the computer

will receive those so you can see here

TX is going to an RX and vice versa

um in the internet Network such as a 10

base t or 100 Base TX pins four and five

of the blue pad and pin seven and eight

of the brown pair are not used

so technically you could have a cable

that um doesn't

um have connections on those pins there

now you're more likely to be using a

faster and connection type if possible

so on the thousand base T ethernet cable

such as cat5v all four pairs of wires

will be used and that's how they get the

faster speed but using the same cable

types

now the crossover cable you can see here

is used to connect like to like so if

you have two switches then you could

connect them using a crossover cable two

router ethernet ports you could use a

crossover cable or if you had two PCS at

home and you didn't want to pay for a

switch you could also use a crossover

cable

used to connect the following MDI device

to an MDI device

you could also connect to um

switches together as we have here in the

diagram the MDI X device

okay wiring for UTP crossover cable

easiest way to remember is one goes to

three and two goes to six everything

else stays the same you can see that

rule applies for both sides so left to

right and right to left

a crossover UTP cable has an eight pin

modular connectors each end is

terminated in the below manner

okay so these devices will be

transmitted on the same pins one and two

these devices will also be receiving on

the same pins three and six might be

worth remembering that case that pops up

in the exam which ones are receiving and

which ones are transmitting

foreign

on one side is connected to pin three

that's what I said and two to six

terminating the crossover

you would terminate by using the um 568

a wiring on one side and the B wiring on

the other so using two different

standards for either end

um if we're on an end of the um cabling

uses the a standard the other has to use

the B that's if you're making the

crossover cable

Auto mdix

it's Auto sensing so do you remember

earlier we had this picture of a hub and

you had to press this um the little

switch on there while modern devices can

actually Auto sense what type of cables

attached and then change the designation

for how it uses which wires on the eight

pins on the inside

and most modern ethernet devices for

example switches use the auto MDI XV

channel so it's pretty handy

this is why sometimes you can plug the

wrong cable into a switch and it all

still works because it's got this

automatic feature

rollover cable is something you will

have with you normally at all times as a

network engineer in your briefcase

and normally used to connect your PC or

laptop to the console port on a router

or switch and it lets you

configure the device when you first buy

it and it's blank or do emergency

recovery for example if you've forgotten

a password to configure the router or

switch

so it has a 8p AC connector rs232 based

connector such as a DB9

this has actually changed now so you can

see the DB9 connector your laptops don't

actually come with DB9 connectors

anymore it's pretty old-fashioned so

what you'll do is you'll have a db92 USB

connector

um and you'll use one of your free

um common connections using device

manager to see which port to connect on

so I mentioned Cisco console cables and

recovering your Cisco router

in order to you can make your own

rollover cable roll over flat console

same thing cable

and the wires are basically reversed so

every yr goes to the opposite number one

goes to a two goes to seven three goes

to six and um carry on with that number

in so basically the whole thing's

Twisted somewhere in the middle

all right so we've covered modular

connectors the A and B wiring schemes

MDI and mdix straight through

and crossover cable

Auto mdix and brown leather cables so

that's all we need to look at for now

thanks for watching

[Music]

welcome to module 2 lesson 1B some more

cables connectors and transceivers this

is all new stuff that's landed into the

network plus syllabus

uh some of it's a little bit strange in

as much as it's almost redundant and I'm

guessing they want you to know this

stuff in case you come across it in an

environment for whatever reason

all right so Network Hardware media and

bound in network media a few things

we'll be looking at

copper connectors uh the stuff we

haven't already looked at earlier by the

way uh transceivers

some termination points copper cable

standards

and network storage connection types

so this is a used to be called uh d sub

actually but it seems to have been

hijacked into DB connectors but you can

see the um the shape of the connector

here is like the letter D really leave

it on its side

I like that so the theory is you can't

uh plug it in the wrong way I say in

theory because when I've run computer

courses it might just be a Cisco thing

because this looks a little bit thicker

but the uh the Cisco um

housing here I was so thin that the

students would come and somehow managed

to plug in the d-connector

for the serial cables upside down now

this did a couple of things it um a

things don't work when they're upside

down obviously with these tiny little

pins they're much smaller than the ones

you see here they actually got forced in

the wrong way and all got bent like that

so that actually cost me a lot of money

it was quite a distressing when I

started up my business

so this is the theory behind the shape

anyway I actually I don't know why I put

into male and connectors here I want to

do have one female but I put into male

used to see these on the back of an old

style PCS and um their laptops as well

you don't really see them anymore

because USBS have replaced all of it so

you'd have to be looking at a fairly old

machine

they were created a long long time ago

before I was born when my dad was a

young man as he used to say 1952

exclusively by Canon and it looks like

they've probably released a license so

that people could use them they were

used in toker ring networks I do

remember those support I actually

supported those for a while at Cisco

although there was hardly any left

it was pretty scary when somebody called

in with a token ring issue external

floppy drives if you remember those and

you'd buy an old real old probably

wasn't even a PC then it was a an Amiga

or Commodore 64 or something and you

could invest extra money to put these

floppy drives in and if you wanted to

load a game you probably have to

individually insert uh I think it was

around 10 floppy drives to upload each

part of the program and I think I did

have to do that for early versions of

Microsoft Word or the equivalent I used

in Mouse connectors also

as I said eventually replaced by USB

thank goodness

the D shape so I've covered this already

the theory is in fact I'm sure it works

for most people I'll just give you a

heads up there when I run Cisco it

didn't work that way

um I wanted the students to plug their

own cables in to have their confidence

but it kind of backfired a bit

I designed to work with the eia tia232

serial interface standard I guess you

should make it out of that for the exam

sort of silly question would be asked

the number DB whatever

so uh what would DB9 or db25 this is

supposed to refer to the amount of pins

that are in the male and female part so

it could be pretty hard to mix them up

actually looking at them you more like

to see the db25 on uh like a printer

cable or something like that again if

you see it at all

now the F connector F-Type has been

added to the syllabus not to be confused

with fiber cables such as stlc SC which

are covered elsewhere in the in the

course here

so it's a coaxial RF connector type

used more commonly for cable satellite

TV if you've got the back of a box you

can see here there's a thread on the

inside of the cable here and you'd have

to turn it round and it'd lock in with

the TR so you'd have to hopefully with

enough finger pressure be able to secure

it into place and then unscrew it those

are when you need to

TV antennas for those user on on using

them your Broadband or Ethernet or

whatever

bandwidth could go up to several

gigahertz

uh punch down blocks this is a pretty

tricky skill really and one that takes a

bit of time but you can see here the

cable has just been placed in between

the runners and then the punch down tool

has kind of got this shape as you can

see here

and this would force the cable in and

the theory is it would strip back some

of this uh coating for the wire and

create a contact inside the punch down

block takes a bit of skill and it's

quite frustrating if you don't do it

right or if someone hasn't used the

correct tool it leads to this nightmare

of intermittent connectivity that you'll

have to go and troubleshoot

you'll typically see this in inside a

telephone switch

um

as switch mechanisms a couple wires

punched down as I said

the numbers are for these models are

given uh 66 Block it's a model number so

it doesn't mean the 66 connectors

that particular one has 55 rows it was

subject to crosstalk which is known uh

quite known quite well in the industry

had a reputation for that not suitable

for high speed connections of 100 Meg or

um or hayab

now the 100 block replaced the 66 block

so just remember the numbers here the 66

block hopefully they won't try and catch

you out with the um question saying it's

got 66 Connections in it's a model

number just to confuse you

often used the 100 is to terminate cable

runs

the fiber distribution plan and panel

how to get images of this but I've I've

got one that you can actually uh buy

from the manufacturer this one obviously

hasn't been set up at all it's a bare

bone system that you would run all of

the cables through here and then

terminate

so this is also known as the fiber

Distribution Hub if you're searching for

one to buy I think they give you

different terms depending on which part

of the country you're in or which

country and at the bottom here I've got

a URL for a particular company that

sells them

obviously speak to the sales advisor and

find out what you need

saves you um making expensive mistakes

this is the patch panel used to

terminate fiber optic cables

access to the cables individual strands

the so the strands inside the cable for

cross connection

now I do apologize for this however

um

it's in the syllabus now for some crazy

reason previously we had um other RG

standards I think it was

rg9 or and RG58 I'll have to check you

you can see it in earlier presentations

anyway however now they've asked for RG6

and

rg59 so I've highlighted what you need

to do I suggest you make some notes

as to um impedance which is all the same

actually so it shouldn't be too easy

um

shielding here and then just make a note

of what they've what they've said here

so

um

RG6

uh Slash U what is used for the uq

again this is just such a pain and it's

silly because you'd if you're having

anything to do with this you just check

the documentation before you went on

site it's very unlikely most Engineers

if you asked most Network engineers and

what can you tell me about rg59 Slash U

there's probably not a lot they could

say however I don't make the rules it's

in the syllabus so just take notes and

just chop that up to something you're

gonna have to learn

uh transceivers I've got some images

here these are for um the SPF SPF plus

and gbic which are connectors for Cisco

equipment these

um

these would stand proud from the switch

chassis and then this would be inserted

in and make contact to the back of the

chassis so here's the front of the

chassis here here and you wouldn't

actually see the back and there's this

has got a nice thin slot that you would

insert to

yeah

do the 3D version so transceiver is

short for transmitter receiver as we

mentioned earlier it converts the

electrical signals from one type to

another type so serial to Optical

signals and vice versa

The Cisco gigabit internet interface

converter we call them gbx it's hot

swappable so you pull it out push it

back in again hot swappable here

is very handy and I think we'll come to

this later actually to find my cursor it

means you don't have to power down your

unit which is just absolute gold if

you're working in a production Network

because it's just horrible especially if

you've got paying customers that are

paying for

99.999 recurring up time and then you

tell them you've got a power down the

device they're connected to and just to

swap out something so very handy plugs

into the gigabit Ethernet port or slot

SPF stands for small form factor

pluggable I guess a gigabit interface

converter that too is hot swappable bear

in mind what you've got to do is check

for

bugs so if say for example you've got a

Cisco device and you've read the

documentation and it says hot swappable

you ask them to do if you've got a

contract a bug

sweep for the

say for example this with the model so

say WC

36 whatever the model is you say I've

got this switch this model uh it says

it's hot swappable and just do a bug

sweep this is I only tell you this

because and this is the advantage of

having someone like myself not that I'm

boasting but I worked at Cisco

and we had a customer who asked one of

our Engineers if something was hot

swappable the documentation said it was

however

um not that it was his fault there was a

bug which he didn't know about and the

customer hot swapped it brought down a

core switch it caused a massive amount

of problems there was I think some legal

claims or whatever it's just headaches

you don't need so if you've got the

contract

and just because it says hot swappable

don't necessarily take that on face

value and if you if you can log a ticket

or do a search

SPF plus is in the hearts version the

hint is in the plus that supports higher

data rates and this time up to 16

gigabits per second

and then finally I don't have a picture

here a quad small form factable a factor

plugable and you've got different speeds

just check the documentation on that I

just wanted to um flag it up I think

it's actually in the syllabus also

uh so we've just got the ghibit module

here and you can see the uh the chassis

would actually be here so you wouldn't

see all this typically and then you'd

have obviously the slot here and I

mentioned that only the the end bit

would be proud and you've got two fiber

cables in here I'm not sure what this

model of the model is that it's actually

plugging into we're just having a sneaky

look here at the um circuit board is SPF

plus and

um yeah so just so you can see it

working in an actual device and however

you would set this up I'm not sure if

this is um these have been linked

together all the ones operating as a

backup to the other so you can see what

it would look like on a live environment

and network storage fiber channel fiber

channel ever ethernet it basically

encapsulates fiber channel frames over

ethernet it's a protocol in its own

right and it was developed just

specifically for this environment and

you can see the um fiber channel over

ethernet is working in this part of the

connection here

and then it looks like we've got ether

channel here which um I don't think

ether channel is specifically covered

but we do

um there's a part of the syllabus that

covers um increase in Europe time I

can't remember what it's called now

let's say there's redundancy we do talk

about later

so uh it's a non-routable network

protocol so it won't go

whatever your connection is it wouldn't

be

carried out here to um

to the internet

it wouldn't work it'd be converted

something would be converted to bgp or

whatever you're using out here

differs from Isco Z which runs over

tcpip

okay this is non-routable so that very

much whether it would be working over

tcpip and then just to tick the Box

Infinity band it's added in the syllabus

um there's a diagram here I got from

melanox whoever they are just you could

um see a topology of it working used in

high performance Computing just think of

exam questions basically why is it used

it's high performance low latency so if

it if it meets your requirements you'd

consider using it

uh direct or switched internet

connection between servers or storage so

it can be server to serve our server to

storage

all right so we covered a lot of ground

but we're just topping up on what we uh

already learned earlier you learn about

some copper connector types transceivers

so it'll convert one type of another one

type of connection to another we talked

about the the DB oops the DB M9 uh I

think the other one was 25 the D

connector and basically the shape is

there

hopefully so nobody plugs things in the

wrong way that's any reason

uh termination points copper cable

standards which is the F standard I

think we talked about which isn't fiber

it could be fiber fibre depending on

where you are

and then the network storage connection

type

all right so that's all for now I'll

look forward to seeing you on the next

presentation

[Music]

foreign

Network hardware and media unbounded

Network media

as we just discussed bounded media is

that media error cabling that is bounded

in the limits of a cable something you

can hold unbounded media as the image

here describes and the image right here

describes is uh Wireless in nature

meaning that there isn't any sort of

chord that you have to rely on and

therefore it allows for certain

advantages and also certain

disadvantages so we're going to look at

the hardware and unbounded media types

involved in these sort of connections

so are the objectives for this module

are to Define unbounded as opposed to

bounded Network media we're also going

to define the difference in radio

networking and broadcast radio

look at something called spread Spectrum

which was created in order to help

Wireless Technologies work more

efficiently and effectively we're also

going to look at IR or infrared or

infrared connections Bluetooth

connections and microwave connections

all of these different types of

unbounded media and devices

and then we're going to look at

something that most of you are probably

more familiar with a wireless access

point also a WAP

then we're going to describe the

characteristics of an SSID which many of

you uh might know as the name of a

network also called the service set

identifier

and finally we're going to look at the

basic uh

ways of properly installing an access

point and by properly installing an

access point of course we're referring

to the network plus methodology of

installing an access point

all right

so unbounded Network media is any

network media that's not bound by a

physical connection such as copper or

wire a fiber that we've just seen

the unbounded simply means it's wireless

or it's using a sort of Wireless

technology Now using unbounded media has

some specific advantages such as it's

easier to install and manage over its

bounded counterparts because you don't

have as much stuff to deal with in the

same regard however unbounded Network

media has the potential to be less

secure than bounded and actually a lot

of folks will say that there is no way

to have a secure Wireless

or unbounded network because

traffic across the network can be

intercepted a lot easier when it's

wireless and anyone can just sort of tap

in in radio networking data is

transmitted as RF or radio frequency so

one of the first forms of communications

this these signals of RF waves were

transmitted in the 10 kilohertz to

uh one gigahertz range

and in the U.S the FCC or the Federal

Communications Commission regulates

these radio Transmissions this kind of

networking is unfortunately very

susceptible to uh Emi

or electromagnetic interference which

we've seen previously especially from

stuff like power lines metallic

obstacles even atmospheric conditions

some people tell me that they lose

connectivity when a plane flies overhead

a radio networking can also be very long

range depending on the method of

transmission the amount of power behind

the signal the kind of antenna being

used the portion of the frequency

spectrum which is located in here that's

being used now with broadcast radio

which is also considered a broadcast

network the signal is sent out in all

directions and utilizes a single

frequency for transmission so there's

low power transmission for shorter

distances is more common and is easy to

install but there's also

high power Transmissions which are used

for further distances as you would

imagine and it's difficult typically a

little more difficult to install because

it requires really specially trained

technicians proper installation and

maintenance techniques and so on with

radio networking line of sight is not

necessary

which means that the

uh this the device sending the signal in

the device receiving the signal don't

need to literally be able to see one

another now because radio networking is

sent over the airwaves uh the signal can

be intercepted really easily and so in

order to utilize the technology for

day-to-day transmission of information

we need to make sure that it's kept

confidential and so a new form of radio

transmission was developed this is

called spread Spectrum

a spread Spectrum was introduced to

address some of the concerns that I've

just mentioned uh it takes the radio

signal to be transmitted and it sends it

over more than one frequency so this

makes it more difficult to intercept the

data in transit now there are two

different types of spread spectrums

first is DSS or direct sequence spread

Spectrum the direct sequence

spread Spectrum that's a mouthful

utilizes multiple channels to transmit

the message simultaneously

so it's going to use multiple channels

and it's going to send that message

all at the same time

with DSS there's also a method of error

checking and it's called edac

which I don't think you'll see on the

test which is error detection and

correction and this allows for a certain

degree of signal loss while still being

able to put the original signal back

together on the receiving end

on the other hand we also have something

called fhss or frequency hopping spread

Spectrum in this method uh it sends the

signal across one channel at a time

and hops to the channel uh each Channel

just just sort of hops to another one at

a predetermined interval

this method can hop from frequency to

frequency anywhere from 50 to a several

hundred uh different frequencies

per second

the sender and receiver as you can

imagine need to be synchronized with one

another and they also have to have the

same uh set of frequencies to hop to

which which is called a hop set

this method of radio communication by

the way is it's commonly used in the

military because it has a fairly

strong sense of security about it

infrared or infrared which you might

have heard of uh

Transmissions

are also unbounded forms of

communication and the and the data is

sent via pulses of infrared light

hence the name infrared this light is ah

between 300 gigahertz and 300 000

gigahertz range and in the in the

electromagnetic spectrum of ranges and

frequencies there are also a few types

of ir that can be used

um all of which need an absolutely

unobstructed view between devices this

means that they are what we call line of

sight

or loss

because of this it nearly guarantees

that there's a secure connection between

the devices because they have to be so

close to one another

another example of infrared being used

by the way is your remote control which

is the reason that we probably found

them on a lot of laptops now there are

different types of infrared connections

uh they're serial infrared which means

that the data is sent in a Serial

fashion uh in this case you're looking

at probably around 115

kilobits per second then we also have

fast infrared which goes up to four

megabits per second and finally very

fast infrared which gives you up to

about 16 megabits per second so you can

see that there is a uh the technology

has changed quite a bit that being said

we don't see this a lot in sort of um

consumer markets just because it is uh

because of the line of sight necessity

of it

now there's also Bluetooth Transmissions

which is another form of short range

wireless communication it's increasingly

popular you've probably seen it with

these sort of headsets and it uses a 2.4

gigahertz frequency which by the way is

the same we're going to see with Wi-Fi

and so that this can actually cause uh

some interference with your at-home

Wi-Fi network now today Bluetooth is

used to connect devices like headsets

cell phones uh laptops mice gaming

consoles

um so on and so forth

the accepted maximum range of Bluetooth

communication is about 30 feet uh which

is equivalent to around 10 meters

but the newest implementation Bluetooth

2.0 is said to reach up to 30 meters or

a hundred feet uh but it's not

guaranteed to run that distance and

um in application it might not actually

get there now when you're connecting

devices by bluetooth we call it pairing

devices uh and if you've never done this

before generally there's a pin code

that's used

to pin these a pair these devices

together to make sure that they are

secure and you're not connecting to a

different device the next type of uh

Wireless transmission I want to talk

about is microwave transmission is the

same

term for that thing in your house the

microwave operates in one one gigahertz

to 300 gigahertz frequency range and for

the microwave transmission to be

received successfully there has to be an

unobstructed view or point-to-point line

of

communication so just imagine that the

satellite uh for your television for

instance if our satellite dish at home

doesn't have a clear line to the

satellite in the sky we see that it's

signal to grade or drop off altogether

so obstructions such as buildings uh

trees even atmospheric conditions like

rain Etc can all play a major factor in

microwave Transmissions one of the

greatest benefits of microwave

Transmissions is it has a really long

range of communication as you can

imagine

uh uh your satellite at home can reach

all the way up to the sky and hit that

uh satellite in the sky or rather your

receiver at home or your dish at home

can reach that satellite in the sky and

so there's a real strong benefit to the

satellite microwave Transmissions

now the one you're probably most

familiar with here is a wireless access

point which is a radio uh a type of

radio frequency device it allows

wireless

devices to connect to a network it has a

network interface that allows it to

connect to a wired Network as well so

generally speaking this would go off to

say a switch or a router now how do we

know which wireless access point we want

to connect to this is something this is

where we get into something called an

SSID and there are also other settings

that we need to take care of when we're

setting one of these up so first let's

talk about the SSID or service set

identifier which is a up to a 32-bit

alphanumeric string and it identifies

the name of your wireless access point

so in some ways we might call this the

name of your network right out of the

box

when you just set it up the access point

is going to do what we call broadcast

your SSID this means that it's

transmitting the name of the network uh

into clear text so that anyone who's

within range can see it if you live in a

building or if you're in an office space

you've probably seen this so This

creates a vulnerability on the network

especially if you want to limit the

number of users that are trying to

access your network so with your

wireless access point there are a few

steps to make to ensure that we're going

to install this correctly uh safely and

efficiently so the first thing we want

to do is to choose the proper device for

your needs obviously there are different

types of access points if you were

around for a plus we talked about what

are called Soho routers or Soho access

points which also have routers in them

but an access point simply is the device

that's connecting you wirelessly to your

network now if you have a corporate

environment or a home office Network

you're going to need different things so

the next thing one once you've decided

which device you want we then have to

talk about where we want to place it and

specifically we need to ensure that our

users can access the network from all

the places they need to which is just as

important as considering which users we

don't want to be able to connect so we

want to be able to place it in a place

that is of course Central but also is

limiting or Limited in the amount of

people who are going to connect to it if

you put it near a window for instance

our next door neighbor might be able to

connect now almost immediately after

bringing the whapper the wireless access

point out of the box we want to change

the administrative default password

so and disable any guest accounts this

means that all these settings that we're

talking about uh you need a password to

be able to get in and change them so we

want to change that or disable the guest

account change that and we also want to

make sure there are no other backdoor

accounts

um you can generally check in your

administrative sort of um manual to see

if there's anything like that so that

way we don't have any unauthorized

access to the account

next thing we want to do is configure

these wireless access point settings

including the SSID what encryption we're

using power and so on

we'll talk about encryption and in

further detail in later uh lessons so

don't worry about that so much right now

figurations have been set we also want

to disable as we've mentioned the SSID

this doesn't mean that users aren't

going to be able to connect to the

network by the way it just means that if

you're looking for available wireless

networks it's not going to be uh

broadcast out there so in other words

you need to know the name in order to

find it it's sort of like a door that's

hidden in the wall if you know where the

door is you can find it if not it Just

Blends into the wall

finally after we've set everything up

the last thing we want to do is test for

functionality make sure that all the

users can connect make sure that they

can get in from the locations they need

to and also make sure that people who

can't who shouldn't be able to connect

can't

all right so now we've talked about a

couple different things first we talked

about unbounded Network media which

again is sort of Wireless

in scope it means there's no chord we

looked at Radio networking and broadcast

radio we also looked at the sped spread

spectrum and if you remember that's we

have two different types one which is

going to broadcast on several different

channels on the Spectrum at once and one

which hops around at certain intervals

we also looked at infrared Bluetooth and

microwave connections these two much

more uh shorter distances microwave a

much longer distance this requires a

line of sight so does

IR Bluetooth does not but does have a

very limited degree of um distance that

it'll work we also looked at a wireless

access point or a WAP by the way

wireless access point is also going to

be built into what's called a Soho

router those are those Linksys or

Netgear routers that you buy at the

store and finally we described the

characteristics of an SSID specifically

the fact that we want to disable their

broadcasting

so we've talked about the bounded and

Unbound media let's talk about some of

the devices this media is going to

connect to

[Music]

Network hardware and media network

connectivity devices

so having discussed the way that devices

connect either using unbounded or

bounded media let's now talk about the

connectivity devices themselves

so the objectives of this module are

first to Define and describe a Nick

which also stands for a network

interface card

this is the main way in which devices

connect to a network

we're also going to talk about a

transceiver a chip that is on the Nick

and basically allows it to communicate

we're also going to identify the

characteristics that make a switch one

of the main Central devices in our start

apology that allows for communication on

a local area network and then we're

going to identify some of the qualities

and some of the characteristics that we

can put into a switch including trunking

Port mirroring and channel bonding all

of these do come up on the exam and so

they are pretty important to cover

then we're going to talk about a router

and a Gateway these two devices allow us

to communicate outside of our local

networks onto a wide area network or a

Wan

now as with anything we have noise that

interrupts the signal and so we're going

to talk about what that noise is and the

sources of that noise so we can better

uh alleviate and avoid it

finally we're going to talk about that

alleviation and avoidance by talking

about noise control and reduction

techniques sometimes getting into these

specifics of how this works now some of

this might be a little too complex for

the network plus exam but it's good to

go over anyway so you have a firm basis

in the theory behind it

so the Nick or the network interface

card is a physical connectivity device

that can be either wired or Wireless for

Wired networks the Nix gonna have an

ethernet port which is right here that

allows you to connect to an RJ45 cable

if you recall the RJ45 cable is the ones

used with most uh twisted pair

installations you can either connect it

directly to the motherboard or it can be

connected through another card or a

riser card or an expansion bus as this

one would be now there are typically

connectivity lights uh on the outside of

the Nic that allow administrators to get

a a quick status of the network

connection the connectivity lights can

mean different things depending on the

manufacture of the Nick however most

commonly there are going to be at least

two and possibly even three and each of

those lights are going to be different

colors you can see on this one we have

three different lights

there should be one light that is on to

dictate that there is a connection

that would be a solid green light most

of the time and it's going to stay lit

when connection and there's also going

to be another light that's sort of going

to flicker the flicker is letting you

know that there is activity or that

traffic is being sent across the neck

the faster the flicker uh typically this

means that the higher the network speed

or the more data that's going over

occasionally you might see one with

different colored lights the different

colors might dictate for instance the

speed of the connection for instance a

green for gigabit speeds which would be

a thousand megabits per second and Amber

for instance for uh 100 megabit speed

across the network okay and this is

going to really vary depending on the

Nick it's also important to know that

the MAC address which might be written

out here is actually hardwired or hard

uh coded into the neck so it's something

that comes with the Nick itself now a

transceiver is a Connect every device

that has the ability to send transmit or

receive traffic simultaneously the

ability that this has is special is due

to a specialized chip that's right here

and this assists the Nick in

transmitting traffic across the medium

almost every modern Nic has a

transceiver built directly on to the

device now a great example of a

transceiver at work is something called

the gbic or gigabit interface converter

this is something that allows the

conversion of electrical signals

into Optical signals

and then back again

the gbit can also be used to convert

different Optical Technologies from one

to the other and this the benefit of

this is it allows a network to be

upgraded without actually having to

upgrade all of the components so if

we're going to be using for instance

fiber optics and copper on the same

network this is something that we're

really going to want I wouldn't worry

too much about transceivers for the

network plus exam but I did want to

cover them because they are listed on

the um

uh on the outline and as I mentioned

they're really built onto a Nick so it's

sort of a subset of a Nick something

that is on the Nick that allows it to

transmit and receive that data and also

allows it to convert sometimes those

signals from one into the other so this

is how a computer is going to connect

let's talk about switches a switch is a

connectivity device that connects

multiple nodes together acting as the

common Connecting Point if you think

back to our start topology we have all

the nodes connected in this way now the

switch looks at something called the MAC

address or that physical address that's

burned onto the uh uh Nick it's a 48

bit

hexadecimal address and we will talk

more about it later

and what it does is it looks at the MAC

address of each packet of data to ensure

the data goes to the proper destination

or to the node for which it is meant now

because of this because the switch looks

at the MAC address of each packet it

ensures that traffic is only going to

the intended recipient a managed switch

just going to write that in here

is a switch that allows an administrator

access to its configuration and is able

to be monitored now the way that this

works is that there's generally

something called a console port on the

back of the device and you use something

called a console cable in order to

access this depending on the manufacture

of the switch this might be light blue

for instance in Cisco switches which is

generally the most common and sometimes

you might have light yellow or orange

for others now switch is forward traffic

to destination nodes via these ports on

the switch

and there might be as little as uh you

know a few ports maybe eight four or

even up to 168 or more now

administrators have the ability to do a

couple different things the first thing

they can do is do something called Port

mirroring

Port mirroring effectively

as the name implies

takes all the traffic on a specified

port and replicates it or copies it to

another port

now this is used for monitoring for

instance if I want to see what's going

on in a port but I don't want to stop

the traffic I can monitor this traffic

for analysis and diagnostic purposes

it's also going to allow administrators

to diagnose whether traffic across the

port is being interfered with by a

nefarious individual or someone who's

has a malicious intent such as a hacker

now if administrators want to combine

two or more network connections

it's called link aggregation

or Port teaming

and there are other names as well what

this does is this serves to increase or

effectively double the bandwidth uh as

well as allow for some redundancy

obviously or a backup connection or

something else another

name you might see this as by the way is

trunking

so that's the one I most see on the exam

so that's again taking two and sort of

treating them as one

finally we have something called Channel

bonding

which is the process of adding multiple

Nicks

to one

Mac address

this is also called Nick bonding and

we'll discuss it in Greater detail when

we're talking about IP addresses and

some of the other protocols

as opposed to a switch a router is a

connectivity device that typically

connects multiple networks or network

segments and unlike the switch it looks

at the IP address of each packet of data

to forward the to the destination node

so instead of the MAC address uh we're

looking at the IP address now a router

is usually used to connect networks that

use the same routable protocols so a

routable protocol is any protocol that

identifies the node

versus

the network

using

addressing

I.E the IP address now a router can be

installed as a hardware device as a

function of a multi-function device like

a Soho router

and uh it's also can be installed as

software in another device in a virtual

environment for instance on a server in

the case of a router being installed as

software in a virtual environment the

device or node has to have

two Nicks one Nick for the note itself

and then one Nick for the routing

functions sort of like one to go in and

one to go out a Gateway is a

connectivity device that's very much

like a router in the way it functions

and it routes traffic in much the same

way but the difference between a Gateway

and a router is that a Gateway connects

networks that have different protocols

or dissimilar protocols that to

communicate so the Gateway performs the

translation between

incompatible networks uh I'm just going

to put translation here since I think

that's pretty important

or

even different uh email systems or

operating systems now although it can be

easy to confuse a Gateway with the

default gateway that we see when we do

an ipconfig it's not the same thing

a Gateway is a device on the edge of the

network that's used to convert traffic

between different systems while as this

default gateway is simply forwards data

packets in TCP so we're going to discuss

that in more detail later but I just

want to point out this is not the

default gateway and just like a router

by the way it can be a hardware device

or software within a router or on

another virtual device and it uses

radical protocols that are similar to a

router but again it allows the

translation between different types of

protocols

now let's look at virtualization a bit

since this is really the the big thing

in Computing nowadays a virtual switch

for instance functions just like a

physical switch you cannot however

directly communicate between two virtual

switches if you want to do that you need

a virtual router or a router now a

Virtual Router is the software that can

be installed on a device with two nics

for routing traffic a virtual server is

a server that operates independently of

its host machine meaning that it's all

software based CPU Ram Etc can be

independent of its host machine whatever

that might be

now virtual machines uh are similar to a

virtual server in that it has its own

software like uh CPA based sorry

software based CPU Ram Nic hard drive

Etc but it's a software implementation

of a machine that performs specific

tasks and executes specific commands but

it's not a server per se all right

remember a server or something that's

serving up information to a client

and then finally we have a virtual

desktop which in Windows systems is a

single desktop

which in Windows systems a single

desktop

is the default that can be open but a

virtual desktop allows you to open

multiple different desktops at the same

time Linux also supports this by the way

but Microsoft requires extra software

that you install for this to be changed

for instance uh virtual PC

we've seen this if you remember with

um an A plus with XP Mode now continuing

to talk about virtualization if an

organization or a company builds their

Network infrastructure and chooses not

to use it they can lease it out to

others so for instance Amazon would be a

great example of this they have a huge

infrastructure but they don't use all of

it so what do they do they lease it out

to others this is a very common practice

and what it's labeled as is networking

as a service

now an area of network as a service or

Naas depending on what is being leased

might be considered one of several

different things it might be considered

IAS or infrastructure as a service

meaning like the hardware

I provide you the hardware provide you

the infrastructure it could be software

as a service much like Gmail

which simply provides you certain

software and just like infrastructure

would be like Amazon's uh

ec2 or elastic cloud and then the last

one is platform as a service

which would be like a an application

sort of engine or uh allowing you to

deploy certain

development tools most of the time

you're gonna see most of these in the

field this one is really more for

Developers

so the term Legacy indicates that this

is a an older device one that's not

really in use in today's networks or

that have been replaced by a newer or

higher functioning devices so some of

the things we're going to talk about in

this one might appear on the exam and

the reason the reason for that is

because they might appear in the field

uh just because they haven't been

replaced yet by perhaps due to expense

or something however these have probably

been replaced by switches routers and

gateways but it's still good to go over

them anyway so a repeater is a simple

device that does not look at the traffic

at all all it does is it simply boosts

the signal after it receives it and

transmits it out so it just repeats the

signal as the name implies just boosting

that signal we also have something

called a hub which you might have heard

of and this is similar to a repeater in

that it only it doesn't look at the data

it just retransmits it but the thing

that a Hub does is it receives traffic

from one port and sends it out to all

the ports without looking at the data

traffic now it's vastly been replaced by

switches because as you can imagine if I

wanted to send data to only one node The

Hub doesn't allow me to do that it makes

me send it to all of the nodes and so

this is going to cause quite a bit of

extra traffic on my network finally

there's something called a bridge which

was the purpose was to divide logical

bus networks into segments and it did

this by looking at the MAC address so it

is operating it's sort of the same level

as a as a switch and it would look at

the MAC address of the packet and

transmitted the data accordingly now if

the MAC address was on another segment

it forwarded it out and if the

destination was on the same segment then

it didn't forward it so in older

networks this implementation was logical

and it was handy because it reduced

traffic congestion and improved

performance obviously because it wasn't

forwarding data that didn't need to be

forwarded on

all right now let's talk about noise

noise or electrical noise and networking

it's the term that interferes with uh

implies rather interfering with data uh

and normal data traffic it can come from

many sources and as Network

administrators it's really important

that we know where all this noise is

coming from and how to prevent it as

well so not only can noise affect our

network uh performance but it can also

affect data transmission electrical

current as well now if electrical

current is interrupted or interfered

with then that can affect our electrical

devices so for instance if there is a

surge in the current that means a lot of

extraneous noise in the electrical line

goes to our devices and then damages

them so sources of noise are found in

many places as you see here is a power

line electric motors used in HVAC

systems elevators refrigerators just

about anything that draws power to run

fluorescent lights neon or height

intensity discharge lights or what are

called HID lights uh also cause

significant amounts of noise that

interfere with networking over both

bounded and unbounded media this is

especially important to be mindful of

when you're running or installing your

cables or placing your wireless access

points you want to really avoid running

data cable parallel to those lights as

well as any cables used for power it can

also come from devices that give off

heat like personal heating devices and

while that might sound a little strange

it's due to the amount of power that

those devices consume when in use the

power or the electricity it has the

potential to give off a lot of noise

which makes sense now lastly normal

ambient noise also called background

noise or the noise that's present due to

atmospheric conditions like solar

disturbances radio broadcasting towers

that are nearby Etc the main thing to

consider with ambient noise is the

distance or the the length of your media

the longer your media run is the closer

to its maximum rated length then the

more susceptible your signal is going to

be so to combat this we one thing we can

do is called grounding which is a method

of taking the shielding or a conductor

and connecting it to an electrical

ground point that is directly in content

with literally the Earth's ground now

when we connect a network segment at one

point to a ground this basically shunts

or drains the extraneous noise

only leaving the data signal so at the

same time if more than one point is

grounded this can introduce even more

noise which is going to greatly reduce

the quality of the signal if not even

completely get rid of it so we can only

we only want to uh ground the point uh

once which is important if we do it more

than once we're going to be in major

trouble not only do we ground for

Network for a performer but we also do

it for safety because most electrical

devices have to be grounded in one way

or the other otherwise you know we just

like we saw with a plus and touching

devices if we don't ground something we

could possibly damage it this is mostly

to redirect uh High voltages

into the ground where they're not going

to harm your equipment now electricians

have special ground points or dedicated

ground points that are designed

specifically for sensitive electrical

equipment these isolated grounds they're

def they're usually going to be colored

orange which helps differentiate them

from normal plugs so if you see an

orange looking plug that is a special uh

isolated ground

now the shielding around a cable as you

can see here on this coaxial cable

um is a noise prevention measure that

takes the noise and drains it through

the shielding away from the conductor in

the center that is carrying the draining

the the data traffic now the shielding

is then connected to a single ground

Point flushing the noise away the

connection between the shield and the

ground point is also called the drain

which is why we say it's grain drain and

this same thing doesn't just go for

coaxial it also goes for STP or shielded

twisted pair as well now because the

noise is often going to be constant the

method of differential signaling takes

two received signals

and subtracts the equal signals

which is typically going to be the noise

of the noise floor and that's going to

give us an end result of Simply the

noise so basically it takes this signal

input which is a digital input signal

and

it takes that subtracts this

and then we can get

a a signal without any noise in it as

you can see

now besides differential signaling there

are also a few other noise control

considerations we talked about earlier

something called termination which is

really important in networking some

cables require termination to be

installed at the end of either uh

the end of either

connection right if you remember that

from our bus and it has to have the

appropriate ohm rating

if you install the Terminator and it

doesn't have that proper ohm rating then

it's probably going to

um uh actually

it won't work effectively now luckily

for us in most cases the Terminators are

installed in these network devices by

default but not too long ago you had to

install them manually and you had to

make sure the impedance or the amount of

ohms was matched it was a fairly simple

task but the specific impedance could

have been marked on a cable jacket or if

a large amount of cable was installed it

just added another step to the process

now something else to keep in mind is

how you run the cable your cable run you

don't want to run data cable and

electrical cable in the same tray and

you should try to avoid running your

data cable parallel to any electrical

cables or any other data cables in order

to reduce what's called a crosstalk

which basically means the signal sort of

jumps from one to the other

now if you keep data cables away from

Motors fluorescent lighting high power

devices like we saw you owe and you

always ground your electrical equipment

and electrical circuits according to the

manufacturer and you allow for uh all

the recommended installation

requirements and grounding requirements

that they provide then you should be

good to go when you're connecting your

cables together and when you're um

running your cables as well so just to

recap what we've talked about here first

we looked at a Nick and a network or a

network interface card

foreign

we describe the transceiver something

that goes on the card and how it

functions we also looked at identifying

the characteristics of a switch which if

you remember use Mac addressing we

defined trunking Port mirroring and

channel bonding remember trunking was

using two or more ports as though they

were one port mirroring usually going to

use for Diagnostic purposes and then

Channel bonding which is uh sort of

bonding those Nicks together we also

described a router and a Gateway which

again operate with IP addresses instead

of Max and they allow us whereas

switches allow us to work within a lan

IP addresses or rather routers allow us

and gateways to operate within a Wan or

a wide area network finally we looked at

some Legacy devices and we defined noise

and the sources of noise including any

of those high power devices and then we

looked at some noise control and

reduction techniques including proper

grounding and

shielding

[Music]

so welcome to module 2 lesson 4 new

topic added to the CompTIA syllabus the

um what is the syllabus number the below

seven

um Advanced networking devices so this

is stuff that we need to be aware of

because it becomes a prominence may have

been in the industry a while but

um now in regular use or big ubiquitous

as they say

so Advanced networking devices Network

Hardware media I'm going to look at

multi-layer switches

wireless controllers a load balancer

IDs and IPS

we're going to look at AAA and radio

server I think that's dotted throughout

the syllabus so we pick it up as a

security subject and also an advanced

networking device

uh UTM Next Generation firewalls Veep

Gateway and in terms of PBX that is uh

content filter so this is one of the I

think it's the first device actually

that Cisco ever

um brought to Market is known as the

um the Cisco pretty hard to see there it

was the AGS uh husband and wife uh first

artist Cisco and I think they had a

colleague that they used to work with

and

um

they actually bought

um the first Cisco switch was actually

created by a company called a kaplana or

kalpana if you pronounce it this was

their very first ever switch and um

switches used to run some old uh code I

think something like um

I think we used to call it

katos and then the routers well there

was no code

um that they because they created it

they created their own code

and that's called the internet work

operating system Cisco brought the whole

thing together now so there's this you

don't have to use the old command line

that work for katos but they they just

weren't compatible at all

so you had to kind of learn how to

program two different type of devices

so this was the early I think this is

from The Cisco Museum actually and

um you can see the Cabana switch up here

so a real old-fashioned connectors uh

maybe the db25s you can see there's no

high speed connections here massive

switch and then your power connector

yeah so I'm sure this is Cutting Edge

when it first came out huge thing in the

1990s but when you're supporting

networks back then

really um there wasn't an awful lot to

it a server router a hub there wasn't

that much traffic because people

couldn't afford the kit anyway

um early 90s the web was invented I'm

sure most people weren't really using it

ethernet was running at 10 Meg half

duplex

a Cisco the early 90s had 251 employees

obviously there were just I think three

people to start and they grew to 251.

and then scroll forwards to the current

ERA and you can see obviously things are

a lot more complicated

we have a multi-lay devices working at

seven different layers of the OSI model

incorporate Wireless into our Networks

recover Wireless later

there isn't anywhere you go now really

where there isn't somebody offering some

sort of wireless connection

virtualization is a Hot Topic

and it's obviously used by pretty much

all of the cloud providers Amazon Google

and Microsoft to

um cut costs and improve performance

cloud computing is a red hot topic that

I encourage everyone to learn video

voice over IP and quality of service you

need to be aware of advanced security

threats and obviously the larger the

network now they'll have their own

dedicated security team for Hardware

software and

um

protecting from employees and that kind

of thing Cisco currently has 72 000

employees I know when I worked there

when was it the early 90s they were

getting rid of slaves of different

employees from the legal team and

marketing teams and some Engineers as

well so I'm not sure if it was ever

higher than that but as stated on the

interweb it's 72 000. this is quite a

lot

so what are the devices that's mentioned

now brought into the syllabus is the

multi-layer switch

switch is generally a layer two switch

is which is the cheaper models will

switch frames at Layer Two and they'll

lay they'll use hardware for this

multi-layer switches operate layers two

to seven you can buy a switch operates

at layers two three four or another

switch and you can see here

I might be clear but the this is

actually uh a connection bracket here

and what happens is this is a switch in

module

that you can buy and Slot into the

chassis so what you could have there

instead is uh there's two

um modules here and depending on what

you buy you could have one here for

voice one here for remote connections

you could have a mini switching module

here or one that's only dedicated for

voice connections you can see actually

these are exactly the same and it looks

like there's USB there if you um connect

in management interfaces a console

connection

and there's what there's one two three

four switching modules here and it looks

like it's got Quad Power as well so if

anything goes wrong with the power

supplies you've got

three

uh possible power supplies I'm not sure

they're probably going to be hot

swappable and I'm not sure if they're

working

uh there's one's a backup four two and

um fours are back up for three and vice

versa you have to check the

documentation but this whole chassis

would obviously be connected into the

cabinet here and you can probably have

um one major switch here and then a

second one to take up um the whole rack

so multi-layer switches operate

multiple layers from two to seven

bandwidth can be up to several gigahertz

and you can stack Cisco switches so they

all become one you could have two or

three switches or becoming one logical

switch

and ports can be switched which is Mac

address a MAC address in or you can

configure them to be a layer 3 port and

Route IP addresses

and I think that's outside the syllabus

how to actually configure it

um so this would be your typical layer 2

switch now if you wanted to uh route so

if these devices down here on VLAN 20

you can see they're on

192.168.20 well that's not a different

subnet to one on two one six eight ten

so this would be host uh one and two for

example on that subnet and this would be

host one and two on that subnet well the

only way because this is working at

Layer Two the only way to Route because

we're we're dealing with layer two layer

3 here and so all layer 2 traffic this

switch would take care of in its Mac

table which we've covered earlier now if

you wanted a route then

um traditionally you would have to send

out the packet to the router the router

has a directory of all the networks 10

20. this network 30 will probably be for

foreign

management traffic or it could be

whatever you want

and then it would route and then it

would decide that it needs to send that

traffic out it could be an interface or

a sub interface

this is uh what's known as a

router on a

stick one armed router or router on a

stick and unfortunately they have the

physical cable

uh will carry all the traffic coming in

and out not a great way to run your

network I mean it's okay if you're in a

small business and nobody would notice

but this is carrying all your bandwidth

and obviously this is a um single point

of failure here this cable breaks all

this interface

or this interface then you can't Route

traffic the only traffic that would then

pass would be

um with it within the um VLAN sorry

uh he couldn't be couldn't pass this

traffic

so this is a multi-layer switch

so call it

um say layer 3 switch

and what happens is as you've seen

you've got the modules that are slotted

in here the more you pay the more

options you have obviously and this

module

here is for switching so you've got all

your ethernet connections and this could

be your routing module and so all

contained within the same chassis and

the technology isn't really covered in

the syllabus but it would switch the uh

traffic depending if it's Layer Two or

layer 3 within the same unit so

basically what you don't have to have is

this device here and this device here

it's all within the same unit and

depending on what you spend this could

be

um doing access lists on also your

connection out to the internet depending

on how how much money you have and what

your requirements are

uh next device is a wireless controller

this is a Cisco 2500 Cisco wireless

controller

has the cheaper devices you've probably

seen you probably got one at home here

is your wireless access points and what

happens is you've got a few um wireless

access points probably say this is your

office

and normally these would take care of

all of the connections what happens is

these become lightweight access points

in as much as all they're doing is

taking in all of the signals and then

passing it over to this master device

obviously it costs a bit more and so

these are lightwork access points and

this is your wireless LAN controller

which some people refer to as wlc

so it allows your wireless devices to

communicate and you can see you've got

some wired connections there as well

takes over from the access points

becoming lightweight forwarders so you'd

have to throw them away which is Handy

the wireless access controller has your

service set ID it can have logical

interfaces and as you can see down here

you've got physical pause for ethernet

and when you first buy it if you want to

you can connect to the console Port here

and then use your PC to set it up to

whatever

um parameters you want and also you can

use this port here for Disaster Recovery

you obviously have to be physically

present unless you connect a Cisco

access server which we'll cover later

which um that would have an internet

connection out here so you could

um and if you said tile Nets probably

ssh in through

um here and then you could from the from

this um

Cisco access over here

you would have a connection going into

your console Port but we'll cover that

later

uh ports can be switched uh so they're

just dealing with Mac addresses or they

can be configured to route

depending on what you need

so your wireless controllers these your

wireless LAN controllers permit mobile

devices to Rome roaming means keeping

the same IP address

now you can have intra controller

roaming so you've just got one

controller or you can have inter control

around me which is a little bit more

difficult but as you're walking through

your say you're in a coffee shop

and you've got

ground floor here and say there's a

concrete which normally is as a concrete

floor and you go up the stairs look at

my amazing stairs there and

you're in the uh first floor I know you

I think you don't have a ground floor in

America maybe the first floor it's

called the first floor but on the ground

in the UK we call it ground floor and

then first and so on what you don't want

to have to do is reassociate with a new

uh controller so basically you'd have to

connect to

um

wireless network one and wireless

network too you don't really want that

you want to go in

connect to their free wireless and then

keep

your IP address so

172.168.1.1 so keep it as you're roaming

around the building

if you're just using lightweight access

points then you would have to just keep

reassociating which in this day and age

is obviously a pain because we're so

lazy so I've mentioned intra controller

and Inter controller you can see in the

diagrams there

the load balancer

so this distributes incoming requests

between two or more devices so your this

is trans this will be transparent

so what your clients think is happening

is basically it thinks this is happening

it doesn't realize that this device is

here which is fine by us as Network

Engineers will will take care of that

and what it will do is balance so it

will take uh the say the first

connection here

and then oh no this is getting really

bad now

it will log internally here and then

this could be

a network or just the device

third connection here and it will

balance

and you don't have a single point of

failure so your third connection goes

here this load hits uh say 90 percent

but this server it could be a higher

powered server it doesn't have to be the

same this is only sitting at twenty

percent

then it will route more of the traffic

to here if this goes down for whatever

reason transparent to all the end hosts

it will load balance between these two

and you can um you could be routing

between different devices it doesn't

have to be servers

so you can balance web traffic streaming

videos databases whatever you so wish

now the IP address is actually sitting

on here

so say uh 12.1.1.1

and then these will have probably have

non-routable addresses so RFC 1918

addresses which is

whatever you know the the

private IP address is

but we won't care about that as

customers moving on IDs and IPS

uh Cisco Market leaders in this type of

equipment

uh I can't see what the model number is

4240. always great to serve the sales

pages for all of these vendors

uh Cisco and Juniper and whoever because

it gives you lots of useful

documentation you can see what's

available

now both of these do the same job they

inspect traffic to detect unauthorized

access

and monitors the network for intrusions

or malicious activities now what it can

do is send an alert which is

um oh no I'm gonna have to draw a

this is actually a a telephone I hope

you impress old-fashioned telephone

there if you recognize that then you're

officially old so you could send a

message to your mobile phone it can send

SMS log messages whatever you so wish or

an SNMP trap and that will

um it could shut down a port or whatever

you instruct it to do

now IPS Works in line so it's placed in

the traffic flow so you've got internet

and I'll stick it here actually

your IPS and then that will go off to

your

router

switch and then your your hosts here

however many hosts you've got

and I don't give up your day job so this

is in line your traffic will come

through here it'll be inspected and then

go to your end device the IDS is not in

line

so what will happen is router

switch

host and it can be put here or here I'll

say there's an ethernet connection here

now your IDs receives a copy of the

frame so the frame I'll call it frame

um frame y

and then

that is just a copy because frame Y is

actually being passed through to your

switch obviously you can see the problem

here is receiving a copy but this

traffic is actually going through your

network so

these are less common now the RDS is

I'm going to talk about these later in

the security sections AAA or radius and

used for authentication to validate the

identity does a few things actually and

um Josh talked about the different

aspects of AAA earlier authorization

determines what you can do and

accounting is for the audit Trail so

this um the accountant will normally go

off to a server where you can

interrogate the server logs and

sometimes you need to do it for

um compliance

or um

if you're going to legally

take a case against somebody

so it's a modular and scalable model for

network and device access you can run it

on its own server or certainly in the

terms of Cisco you can have the server

software running on your router and

switch probably not recommended because

routers are designed specifically to

Route traffic

uses radius attack ax plus and curb Ross

as authentication methods don't I don't

think airbrush is actually in the

syllabus but I know a radius attack ax

is certainly worth looking at the

CompTIA Security Plus which we go into a

lot more detail in this stuff

I've already mentioned using the service

uh UTM is an appliance

integrates a range of security features

but it does it into a single Appliance a

while ago actually I was when I was

Consulting in the early

2003 there was one company in particular

brought out everything in a box bearing

in mind the needs weren't as complicated

back then so this box

let's say boxer server we do your um

email it would do your web

it would get you out to the internet as

well and then it would obviously connect

off to your

switch and I think it also had your

firewall there's a few things it did but

basically this was everything in a box

that a small business would need

so it does several things and it's

designed to do them all pretty well your

firewall your antivirus your IDs or IPS

you can it has VPN software built in

brands that you want to check out that

are Market leaders at the moment are so

fast which this is a copyright from

their page

and why jungle

a lot easier for you to install and

manage most of it will be running off

the graphical user interface so rather

than have to configure a Cisco device

which is frankly quite a nightmare for

most people unless you know what you're

doing

uh it just makes it a lot easier

probably I'm I'm saying it's more

suitable for the check the software

because they may say different the small

business the small to medium-sized

Enterprise where you don't have a lot of

employees and you may just have one

support person or somebody that comes in

just to do patches and maintenance

obviously saves time and money so a big

pull for any small businesses

the only problem is if you're running

everything off this I guess it's running

off a server of some sort because it's

software based then you've got a single

point of failure so you've got to take

this

um into account with your business

continuity planning what you're going to

do if it part of it breaks all of it

breaks

Etc

ngfw Next Generation firewalls so the

hackers as you know are getting smarter

and smarter and smarter and whereas and

we'd have to be checking the IP headers

or the TCP headers to find any malicious

code it's actually now being buried

inside the application data and

traditionally your firewalls May well

have been just checking these particular

Fields headers Footers trailers whatever

so I just got this image off um this URL

here so these are known as third

generation firewalls

this combines your firewall with your

other filtering looking at application

and this is where the crypto lockers are

hiding which we cover later

and it can include antivirus ID

management your transport layer security

which is the latest version so secure

sockets layer quality of service if

you're running it on your network so if

you're trying to prioritize Voice or

video conferencing whatever you want to

run at your work

uh command firewall antivirus Gateway

IDs IPS VPN software

now eighty percent of the malware now

targets your application so this is

this is the software stuff and normally

we wouldn't have been inspecting inside

this part of the packet but this is

where they're hiding it now and so you

might things that have been downloaded

off the websites or in hidden inside

emails so this is why we need this third

generation of firewall

so blocking ports and filtering is no

longer enough unfortunately so I mean

just um Gathering more data spending

more cash and having more stuff to

support what this is known as here is

deep packet inspection DPI so we're

looking deep inside the IP pack here to

see if there's anything nefarious in

there

the Deepak inspection you can see things

that you wouldn't normally see looking

at the headers and Footers and trailers

worms viruses and it can also do so most

importantly at wire speeds so the thing

that we all hate in networks is

latency I.E slowing stuff down it's

really bad news for us and it obviously

frustrates the users especially if

you're doing voice and video

conferencing it would be a nightmare

they've added a voiceover voice over IP

PBX into the syllabus

and you can see we've got the voice

Gateway router here I've got this from

this website here easytalks.com so

you've got your uh public switch

telephone Network which Josh talked

about which is your voice stuff and then

we've got our traditional phones uh

we've got our IP phones been managed

here so we can all communicate within

each other and then your voice PBX if

you need to make calls to traditional

landlines that can go out through the

traditional public switch Network

so IP private Branch exchange is a phone

system and it but it also offers IP

connectivity you get your traditional

extensions connecting through your Lan

and obviously you can go through

the internet if you've got your

traditional IP phone and you want to

call somebody in the remote office with

another IP phone

and you can do that okay otherwise it

would have to go through to the public

switch telephone Network

you can buy actually software so it'll

run off a server if you so wish or you

can have a hardware where you have to

wire it up yourself

mentioned it connects to the phone

network and obviously use it if invoice

is enabled on your network

content filters

uh what you can and can't uh Surf and

I've got something similar on my home

router although the Fairly rudimental

level where I can block stuff that and

the kids shouldn't be watching also

referred to as information filtering

depending on where you are usually

software based and it's it's very simply

blocks harmful websites or files such as

Dot xees

it would probably uh block

um Facebook

Instagram stuff you don't want people

surfing while they're at work also

you can work your local network so your

um

office here you could actually have it

working for your core Network

or you could let your ISP take care take

care of it sometimes they're actually

automatically block

and certain content and certain websites

especially in some countries where they

they control politically what you can

and can't say I think um

Egypt and some other countries where

they don't want you to see certain

things

which I won't go into that uh so your

voice is enabled sorry that's uh but

they're in error from another slide

so multi-layer switch we've talked about

your wireless controllers turning your

access points into lightweight access

points so they just forward traffic and

your wireless LAN controller takes care

of all of the routing security

associations

ssids that kind of stuff

load balancer where it's sending your

traffic transparently to two or more

servers and obviously it's got your

um

the capability of if there's a one of

your servers goes down it can balance

between what uh or others are left

RDS on IPS uh you've got to bear in mind

what's in line and then what is out of

line and just receives a copy because

that's your typical exam question

AAA server which I'll talk more about

later uh UTM again probably small

to medium-sized Enterprise but do check

the marketing spiel

Next Generation firewall which is deep

packet inspections voice

again if you're going out to the

public switch telephone Network you'll

need the voice Gateway contact content

filter is blocking sites or content

definitely dot XC files

and um even even my online file that I

share with my providers some of my

Freelancers that work for me they can't

reach this on them from their corporate

Network either they're often blocked

all right so that's all for now thank

you very much for listening

[Music]

foreign network communications data

transmission

as you may know computers talk in bits

ones and zeros ons and offs and this is

how all of the data that we deal with in

computers is transferred from one

computer to the next or one node to the

next over the media as we've discussed

but we want to talk exactly about how

these bits these ones and zeros get from

point A to point B and so in this uh

module we're going to talk about data

transmission

or how data makes it from one point to

the other

so we're going to start by talking about

data transmission methods and defining

exactly what data transmission is

we're also going to talk about

instantaneous data transfer and what

might require it the word instantaneous

meaning the data is sent instantaneously

the minute that it is created in some

instances data is first stored and then

converted and then transferred in this

case instantaneously the data is

transferred over the media we're also

going to discuss which we've seen in a

plus serial data transmission meaning

that one bit is sent at a time one after

the other and remember just as uh you

can recall one byte

equals

eight bits

byte being represented by that uppercase

b and a bit being represented by the

lowercase b

we're also going to talk about two

different communication methods in

serial data transmission asynchronous

and synchronous Communications with

which have to do with uh how the data is

synced up to a clock cycle with the CPU

and therefore how it's sent

then we're gonna have to find parallel

data transmission meaning that the data

instead of being sent one after the

other you may have eight bits of data

all sent at Once In Parallel with the

other

finally we're going to discuss baseband

transmission a digital transmission

method and Broadband transmission or

analog transmission method these are

specifically called out in the network

plus exam and so it's important that we

pay a special attention to those now

when we talk about data transmission

it's important that we have to

understand there are many ways that data

can be sent and received in essence data

transmission is the exchange of data

between devices on network by one method

or another the main thing that

differentiates data transmission from

say Voice or telephony transition is

that we're transmitting many different

things including text video and Graphics

all over the medium whereas telephony is

only dealing with voice this is

different from our telephones which are

are also transferring a sort of data but

that data doesn't include as many

different things

now when you might hear the term

computer network I just want to be clear

that computer network is the same as a

Data Network and so we might be using

those terms interchangeably but when

we're talking about data transmission

sometimes the term computer network as

opposed to Data Network comes up but

they are interchangeable

now in most cases when we're dealing

with networking the data is stored

somewhere at some point this also goes

for data that's ready to be transmitted

right we store it and then we send it

however there are some instances when

data needs to reach its destination as

soon as it's been generated or created

and we don't want to wait for it to be

written to memory or written to a hard

drive in these cases instantaneous

as the name implies being instant to the

moment data transfer occurs some

programs and applications such as online

chat uh video conferencing and voice

conferencing programs all via the

Internet require such a transfer the

this method of data transfer doesn't

store the data at any point before

transmitting it to memory

instead it immediately converts that

data into a network compatible format

and as it's being generated and then it

instantaneously transmits it now you can

understand why we would want to use that

in these specific instances I don't want

to store my chat stuff to memory and

then send it I want to chat and then

have it sent same with video

conferencing or voice conferencing I

don't want the lag that's going to occur

due to having to save it to memory and

then save it and then send it which is

why we want this instantaneous data

transfer

serial data transmission is a

transmission method that transmits bits

once per clock cycle now this clock

cycle refers to the CPU or central

processing unit of the computer and how

that's processing information and as you

can see from this illustration basically

what happens is we're sending one of

these bits

at a time

and if you recall

one byte equals eight serial bits and

that's what we're going to call eight

serial bits one byte now a couple

examples of what's uh of what uses

serial data transmission includes

ethernet as well as some peripheral

devices that connect to our computer

like mice and keyboards now with serial

data Transmissions there are different

methods that can be used to delineate

between the start bit and the stop bit

basically how they know

uh what where the data begins and ends

and also error checking or correcting

bits that allow the data to be uh fixed

in case it arrives incorrectly and the

data itself so let's take a look at the

difference between synchronous and the

asynchronous methods of data serial data

transmission

synchronous data transmission

utilizes standardized time intervals

when transmitting each bit now the

assumption that is made is that one byte

is sent every interval so the two

devices have to be in sync with each

other each other in regards to their

timing a clock chip therefore

not a great picture of it but imagine

that this is a chip is needed to ensure

that the devices are in sync with one

another now a special bit pattern is

inserted during a specified time

interval to maintain this

synchronization

asynchronous on the other hand uses

special start and stop patterns to

differentiate between the bytes in the

data Stream So the receiver just has to

look for these special patterns and then

can easily keep track of whether the

data has been successfully received so

for instance the pattern might be one

zero one zero and then uh or one zero

one zero one zero one zero and then the

device knows that that is the beginning

or the end of a pattern of bytes of data

the benefit of course is we don't need

this chip because the start and stop

times are built automatically into the

data itself

now stepping away from serial data

transmission

parallel data transmission is a transmit

Mission method that uses multiple

transmission lines wires or cables

simultaneously unlike serial

transmission that sends start and stop

and synchronization bits along with the

data parallel does not and doesn't have

to those bits are sent separately via

one of these multiple other different

transmission lines other than the data

because of this throughput is generally

better than standard serial transmission

and these eight of these parallel bits

are referred to as a character as

opposed to a byte now some examples that

use parallel transmission are scuzzy

parallel ports PC card or

pcmcia remember piece parallel ports

those are those printer ports

and may all use parallel data

transmission it's not as used or widely

used as a serial data transmission is

now that deals with how the data is sent

let's deal with the type of signal

that's sent

in baseband's transmission this utilizes

digital signals sent via a direct

current pulse and remember we're talking

about direct current versus alternating

current with base bands all the devices

share the same medium or Channel and

can't transmit and receive

simultaneously however multiple baseband

channels can be combined over one medium

to use a channel separated with specific

time slots and that's how we can

determine when it's being sent and when

it's being received one thing to notice

in a digital signal as well is that

we're only dealing with ones or zeros on

and off and so the signal is either on

or off there's no sort of wave that

we're gonna get with the analog signal

which we'll see right now

so where baseband used those digital

signals to transmit data broadband's

going to use analog signals and you can

see that represented in this wave also

unlike baseband Broadband utilizes the

entire bandwidth available and it's only

going to travel in one direction or

unidirectionally because devices can't

send and receive over the same channel

now if more throughput is needed that's

fine we can combine and send across

multiple frequencies channels or we can

use over just one medium

generally speaking we're going to see a

lot of broadband in the field because a

lot of our current infrastructure was

created for analog signals as opposed to

digital or baseband signals now

Broadband over power lines or BPL is an

emerging technology that still mostly in

the testing phases in the US the premise

of it is that we can essentially bring

high-speed internet

two power outlets using the power lines

and the infrastructure that's already

been built once this technology is fully

developed you would be able to plug your

computer into a power outlet in your

home and you can get decently fast

internet between 500 kilobits per second

and three megabits per second which are

about equivalent to DSL or cable speeds

now of course the main concern with this

type of transmission is a the effect

that the uh since we're dealing with

electrical interest infrastructure the

effect that the electricity is going to

cause uh on

uh the data being sent remember we were

talking about Emi and crosstalk and the

noise issue previously and also security

since if we're using something that

everyone has access to we're also going

to be opening our data up to some issues

so for these reasons we might not ever

see BPL or Broadband over power lines

really come to full fruition especially

with the prevalence of Wi-Fi

technologies that are now becoming uh

installed all over the place and might

make BPL extinct before it even has a

chance to flourish

so just to cover what we've talked about

we talked about data transmission uh

meaning that we're transferring data

over a computer or a Data Network we

looked at instantaneous data transfer

which means that the data is not stored

to memory

we also talked about serial data

transmission in which one bit is sent at

a time

and remember we have eight bits

in a byte

we looked at asynchronous versus

synchronous communication synchronous

requires some sort of clock chip whereas

asynchronous embeds

start and stop

into the transfer

we also looked at parallel data

transmission having bits sent all

concurrently at the same time not as not

as widely used and remember although I

don't think you'll see this

on the exam eight parallel bits

equal one what we call a character

we also looked at baseband transmission

the important thing to remember there is

that it is digital and Broadband

transmission which is analog

finally we talked about BPL or broadband

over power lines which is a technology

that would bring Broadband speeds over

the power lines that are already in

place

[Music]

thank you

network communications media access

methods

so we've discussed and explained the

different media and the different

devices that exist on different types of

networks and we even just talked about

how that data is transferred from point

A to point B but we have a lot of

different devices of buying for access

to this media in order to send its data

and so we need to create certain rules

that provide access to the media and so

what we're going to talk about in this

module is first what media access is and

why we need it and why we need to

understand it for the network plus exam

and as administrators we're also going

to describe two different barrage

areas of media access including

contention based media access versus

controlled media access one in which we

sort of fight for access to the media uh

contend for it if you will and the other

in which it is controlled generally by

some sort of central device

and then we're going to Define uh

multiplexing which allows us to send

multiple signals over a single medium

and we're going to talk about two

different types of multiplexing time

division multiplexing

and frequency division multiplexing

and we'll discuss how those work and why

we need two different ones

then we're going to discuss polling

which is how we check to see which

devices need to send

um

data

and we're going to differentiate between

csma CD and CA now csma you don't really

need to worry about that but it does

stand for carrier

sense

multiple access

but the real important thing here is to

know the difference between Collision

detection

and collision avoidance and these are

the two main methods we're going to see

uh for ethernet

and then for wireless and we'll explain

why that is later on

finally we need to differentiate between

a contention contention domain and a

broadcast domain basically uh how large

or how many other devices they need to

contend against or that can get

broadcast a certain message and these

are also divided by those two different

devices that keep coming up switches and

routers

so if that seems confusing enough to you

let's delve in in order to shed some

light on what all of this is now as

administrators it's really important

that we understand the rules that are in

place for different types of networks

for instance if I were in a crowded room

and I had a secret message that I needed

to get across to someone in the corner

of the room and I were just to shout out

that message there's no rules in the

world that say everyone else has to

ignore what I'm saying and they could

just listen or or there's nothing that

says that everyone else couldn't talk at

the same time meaning that then my

message wouldn't make it now that's

means there's no rules for communication

in real life but in networks and

computer networks and data networks

there are many different types of rules

and here we're going to talk about some

of the media access rules or the rules

that govern which node or which device

has access and the ability to transmit

on the media at any one time and when

they're allowed to send and receive and

for how long now these rules are crucial

they ensure that data delivery and

integrity and by the way when we say

Integrity we mean that the data we

intended to send is actually what was

sent it hasn't been tampered with uh are

maintained now there are two general

categories for types of media access

these are contention based and

controlled media access so let's take a

look at the differences between those

now and they'll come back when we talk

later about csma CD and CA not to

mention contention broadcast domains

with contention-based media access nodes

on the network are competing with one

another for media access time and

utilization another term for this kind

of media is competitive or Collision

based and yes that means that they're

actually the data packets are colliding

and that's how we determine which can go

right which is allowed to be sent now

these are pretty easy to implement

however data can be delayed for nodes

that need immediate access to the

network media because collisions are

going to occur as the name implies and

that's going to delay Network traffic

now as a opposed to contention-based

Media access we also have controlled

media access so instead of me fighting

for access to the media I'm granted

access to the media and the way this

works is we use a central device that's

put in place to ensure that access to

the media is guaranteed for devices that

have certain time sensitive data and

they can transmit it when necessary

because of the because of this and these

devices that need to be added these are

much more difficult to implement and

maintain but they're highly reliable as

you can imagine and also make sure that

no device has more access than another

when it comes to access time so take for

instance a device that has a safety

function that when an emergency event

occurs right it has to have immediate

access to the network and to the network

resources so it can send instructions to

say heavy machinery that needs to shut

down in case an emergency in that case

we don't want it to be intending for

Access we want it to be granted

immediate access and so this is where

controlled media access can really come

in handy

so while we're talking about controlled

media access and we've just talked about

controlled and contention based media

access let's keep talking about control

based media access more specifically

discussing a few different controlled

based uh or controlled media access

methods the first I want to talk about

is called multiplexing and multiplexing

is a controlled media access method I'm

just going to add control there so that

we remember that this is related to

controlled not contention based it takes

multiple signals and combines them over

one single Network medium now data can

actually be multiplexed using two

different methods time Division

multiplexing and frequency division

multiplexing so let's first look at time

division multiplexing this is where

channels are divided into time slots and

each node on the network is assigned a

specific time slot

during that time slot the node has

dedicated sole access to the network

until that time has ended and then the

next node is allowed to transmit now

there's a device that we're going to

talk about in just a minute called the

Mox and this MOX takes the signals from

each of the nodes and sends it across

the network

now with TDM multiple

base band signals and remember baseband

is

digital

again represented here by that Digital

Signal because there is no curve in the

wave which would be analog and we'll see

that in just a second

it allows these digital signals these

baseband channels to be combined and

sent over one network medium

on the other hand we also have something

called frequency division multiplexing

this is where data from multiple nodes

is sent over many different frequencies

as opposed to given a specific time each

node has complete access to its

frequency and dedicated communication

with the MOX that device that is

basically controlling all of this

the mux combines the received signals

from the nodes and then transmitted

across the medium the important thing

you're here to know is that this we're

dealing with Broadband or analog signals

now we've been talking about

uh the mux so let's just talk about that

really briefly the MOX is the central

device that or which is also called a

multiplexer

that combines the signals and transmits

them to the receiving end or a demux or

a d multiplexer separates the signals

out again now remember this is all

controlled access and this mux is that

device we were talking about that is

doing the controlling now a different

type of controlled media access method

is called polling and as the name

implies we have a central device as well

that goes to each node in the network in

turn and C's and queries them do you

have any data to transmit with polling

then there is guaranteed access because

the process is constantly repeating

basically it's just constantly if we

have this middle mux sort of device it's

constantly going

to each

device and saying hey are you ready to

send something you now have access

although this guaranteed access in this

method is reliable it might not be as

effective in time sensitive Networks

and time can affect sometimes

potentially be wasted

in this querying in this polling because

sometimes I'm having to ask devices that

don't need to transmit anything to if

they need to transmit so this basically

wastes time another example of this by

the way is if for instance node a at one

point

finds it as data to transmit node a has

to wait until basically the polling

device comes all the way around to it

before it's allowed to transmit the data

now this can take a lot longer than

simply just asking if it can then just

send the data along

now because of these negatives there's a

variation of this polling which is

called demand priority where each node

signals when it has to transmit or not

transmit this method contains within it

measures to Grant priority to nodes that

have immediate data that it needs to

transmit it also contains measures and

controls to ensure that nodes can't

constantly signal they have priority

data because then you would have one

device that's constantly sort of hogging

your network so those are our controlled

based media access let's and and really

we we see these employed in certain

circumstances but you're going to more

encounter

contention-based media access and in

contention-based media access there are

two different types I want to talk about

Collision detection is a

contention-based media access method

that attempts to provide Collision free

data transfer in Ethernet local area

Networks so the key here is this is what

ethernet uses with csma CD or Collision

detection nodes transmit when they have

data to send and then when a collision

occurs they're basically detected

managed and then the data is resent or

retransmitted appropriately to get a

better sense of this and because it's

one that we really need to understand

let's take a look

at um an image to give us an idea

so there are five steps in Collision in

this Collision detection which again I'm

just going to throw this up there is a

contention

based media access method

in step one we just say that the node

itself wants to uh transmit data so what

it then does in step two is it basically

checks the network for availability

now in step three the node transmits

that data and waits for an

acknowledgment from the receiver that it

got there which is called an ack

packet an acknowledgment packet in step

four this is where stuff really happens

uh if there is a collision the packet

size will identify if one occurred

because what happens is boom I have this

collision and now my packet size changes

so in step five if that Collision

occurred both transmitting nodes and by

the way the reason a a collision is

going to occur is because another device

is also trying to transmit at the same

time so in step five if the Collision

occurred I wait a set period of time and

then I try to retransmit again now this

might seem like it's not a very

effective way of transmitting data but

it happens at such a fast speed that

actually it works quite well as long as

we don't have too many devices in the

same network contending for Access which

we'll talk about in just a bit now you

can understand why this works really

well in Ethernet networks wired Networks

because I can continue to collide and

then send something out again and many

times as I need until the data gets

there but in wireless settings this

isn't really going to work so well for

us in this case we're going to use

carrier sense multiple axis collision

avoidance meaning we don't want a

collision to occur

in this contention-based media access

method there are six steps that provide

Collision free Communication in Wireless

Lanes specifically now similar to csma

CD nodes transmit when they have data to

send however the node takes preventative

measures basically by sending out a

jamming signal or a signal to all the

other computers that tell all the other

computers that there is uh something to

be sent

and therefore no one else is going to

send anything for a set period of time

so let's take a look at this in a visual

way

so the first step in here like with the

CD or like with CD as opposed to ca is

that the transmitting node has data

descend now the node checks the network

for any Jam signals being transmitted by

other nodes basically uh has another

node already sort of said hey I need to

send something if not the transmitting

node

sends uh its own Jam signal

saying hey no one else send anything

because I'm gonna send something right

now

then it waits a set period of time to

allow all the other devices to receive

this Jam signal and then it transmits

the data

now in Step six which is the last step

the node monitors the network for any

other Jam signals from other nodes and

if a signal is detected it halts its

transmission Waits a delay and then

tries to transmit again

this process as you can tell allows

wireless devices to communicate

efficiently in a contention-based

network one in which it's contending for

the right to send and receive data so

this allows all nodes to have relatively

equal access to the media

now we need to have a an area in which

all of these are going to contend for

Access and in a contention domain nodes

on the network are allowed to compete

with each other for media access and

then the collisions might occur as a

result but this is why a contention

domain is also considered a collision

domain because this is where these

collisions are going to occur now in a

contention domain switches control the

size of this domain and in larger

networks we want to make sure to vot to

divide these into smaller networks so

that way we're not having to contend

with as many devices at the same time

so

on the other hand a broadcast domain is

simply a logical area of the network

where all the nodes can communicate with

all the other nodes without having to go

through a centralized device because of

this the device we're going to use is

actually a router which is going to

control the size of the contention

domain in a broadcast domain now the

broadcast domain refers to the set of

devices that are going to receive

broadcast data Transmissions from any

node on that portion of the network

which is also called a segment

essentially if a node were to transmit a

broadcast message the broadcast domain

dictates where the message is going to

go

now in a contention domain if a

broadcast message were to be transmitted

there's going to be a greater number of

collisions as a result of the traffic

you can have multiple contention domains

that make up broadcasts that make up a

broadcast domain so I can have again

divided by switches two different

contention domains

and multiple ones of these can make up a

larger broadcast domain and

because these switches are all connected

by one Central router when one of the

nodes branching off of one of the

switches sends a broadcast message

the router dictates that only the

connected switch and its devices are

going to receive that broadcast

transmission

so we first talked about defining media

access basically the rules by which

devices are allowed to communicate on

the network we then looked at the two

broad categories of access or media

access that we deal with

contention-based media access meaning

we're basically fighting

for the right to access the media or

controlled media access in which we have

a central device that decides for us

we looked at then a couple different

types of controlled media access these

are all controlled media access types

multiplexing which allows us to send

multiple signals over one media and we

looked at TDM or time division which

divides It Up by time and remember this

is for digital signals and then we

looked at frequency

division which allows us to use analog

signals or Multiplex analog signals

remember both of these use a device a

controlling device called a Mox

or a multiplexer and a d-mox or D

multiplexer

we also described polling in which we

ask are there any devices on this

network that want to send data but we

talked about the fact that this can

actually add more time to the process

since I have to ask every device before

I get back to the device that's ready to

send

we then looked at two

contention based media access methods

carrier sense multiple access Collision

detection and collision avoidance and

remember the important thing to know

here is Collision detection simply has a

collision occurs and then I just wait

and I try sending again and this is what

ethernet really is going to use as

opposed to collision avoidance

which is going to be used mostly

in Wireless situations because I send

out a jamming signal first

we then looked at the difference in a

contention-based domain

or where we're contending for Access and

remember that's defined by a switch

because a switch uh everything connected

to the switch can contend for Access and

can have a collision and a broadcast

domain which is

created by the router and is simply a

logical division of all the devices that

uh one device can contact

[Music]

thank you

network communications signaling methods

we've talked about digital and analog

signaling quite a bit but we haven't

really gone into what that exactly means

at a waveform level at a basic level and

so in this module I want to cover some

of the background information about

these and outline some of the attributes

that go along with them

now this information might not

specifically be on the exam but I think

it's still good background information

to understand anyway

so uh in this module we're first going

to Define what a signal is and what

analog is

we're then going to talk about the

attributes of an analog signal

well then take this and talk about a

digital signal different from analog and

a digital data transmission or how this

digital Signa is transmitted

we're also going to Define modulation

and outline the Way digital signals are

modulated and modulation really has to

do with uh length or making sure that a

signal can be broadcast or sent over a

very long or large

area

or distance

finally we'll look at Digital Signal

reference methods how we know when the

message begins and when it ends and

finally wind up talking about Digital

Data units or the unit of measurements

that we hear often when we're referring

to Digital Data such as kilobytes and

megabytes so at its most basic level a

signal is simply data or information

that is translated into measurable

transmittable and receivable formats

meaning that it is what allows us to

transmit and receive data

now an analog signal is a signal that

carries data in a continuous stream or a

waveform via either electromagnetic or

Optical energy and this energy can come

from many different sources uh

such as a electric current

and the analog waveforms characteristics

determine the information that it

contains because the analog signal will

oscillate between minimum and maximum

values over time

basically the analog signal has many

attributes to it and it can be read in

many different ways depending on the

values and the information in the

signals given

now this analog signal as I just

mentioned is many different possible

values depending on the characteristics

and how that signal is being read now

the characteristics of an analog

waveform can be described using the

following terms these won't necessarily

appear on the exam but they're good

background information for you anyway

first we have the crest or the peak of

the signal this is the distance from the

midpoint to the topmost part of the wave

and when we talk about the midpoint we

talk about this line that's sort of

going through

inversely the trough is the distance

from the midpoint to the bottom most

portion of the wave

now the next term I want to talk about

is amplitude amplitude is exactly one

half the distance between the crest and

the trough of the wave so it would

either be this could be the what it's

measured it could be the amplitude

alternatively

this could be the amplitude

and the cycle is one complete

oscillation of the wave from start to

finish changing from one state to

another and Back Again basically from

the midpoint going up until we get to

the next midpoint

after it goes down

now the wavelength is determined by the

distance between two consecutive troughs

or Peaks so here we're measuring the

wavelength between two troughs we could

also measure it between two peaks like

so

now the frequency also called the period

of the wave is the number of complete

cycles per second in a wave this is

generally measured

in hertz such as gigahertz or megahertz

now the last term is the phase of the

wave

the phase is the relationship of the

Cycles beginning to a fixed point in

time meaning if two waves with the same

frequency are transmitted at the same

time

they are said to be in phase and two

that are purposely offset from each

other or if they have different

frequencies like these do they will be

out of phase

the device that plots the amplitude of

an analog signal what would show you

this wave is called an oscilloscope

and you may have seen this perhaps at a

store or even on TV and we can measure

waves of all sorts of things for

instance sound might be a wave that

you've seen when you're running a

program on your computer this gives you

a real-time view of the analog waveforms

and its shape if we've just as we've

just described now unlike analog signals

which can have many different values

assigned to them Digital Data

Transmissions utilize voltage

differences represented either by ones

and zeros these ones and zeros are what

make up all of the information

when there is a presence of a signal or

voltage meaning that it is on it

translates to one

and a lack of voltage or an absence of

this signal translates to zero now in

computer networks digital waveforms can

switch between two voltage levels

depending on its relation to the ground

if you recall what that is

now because digital signals utilize

voltage to represent its values of ones

and zeros this is also called The

Logical state of the data

each bit or binary digit takes a

predetermined period of time to transmit

and bit patterns are used to establish

the start and the stop of the sequence

and the sink clocks which allows the

receiver and the sender to be on

basically the same page the sender and

the receiver have to then synchronize

these clocks to ensure proper reception

or receipt of the data now there are a

couple different ways that we encode in

order to allow devices to tell which bit

is what in other words to tell it when

it starts and when it ends

the first method I want to look at is

called on off keying this looks at the

voltage change

from one state to the other

within a pre-specified interval

which is represented by the binary digit

one and the lack of voltage or no

voltage is represented by zero as we

just saw now the synchronization between

the sender and the receiver occurs with

the receiver waiting for a series of

ones

because of this there is a potential for

problems to arise especially when the

sender has a long series of ones to

transmit within the data this means that

it could take a long while for the

sender and the receiver to synchronize

their clocks together

in the event that the clocks are not

sync then there's a high probability for

data corruption as the receiver can't

determine how many ones and zeros have

to be transmitted now there are two

variations of on and off keying I have

listed here

one is called the non-return to zero

variation and the other is the

non-return to zero inverted

this type of data encoding scheme is

typically used over serial ports and

fairly slow connections

I'm mentioning these because uh they're

good to know but you won't have to worry

about these for the exam

now the next encoding scheme a little

more popular perhaps is called

Manchester encoding this scheme was

developed in order to address some of

the downfalls that we saw with on and

off keying firstly Manchester encoding

uses voltage differences to represent

both binary digits so instead of just

having one which is represented by a

voltage and then zero which has no

voltage both zero and one have voltages

the way it does this is it works by

assigning the voltage change from

positive to ground

or the binary digit 0 and a negative to

positive change equals the binary digit

one so

positive to Ground Zero

negative or ground to positive

equals one

this effectively eliminates the issue of

too many one bits being transmitted and

throwing off the synchronization as we

saw with on and off King which relies on

those one bits in order to sync up the

clocks

okay so modulation is the process of

taking a weaker lower frequency analog

signal that can't travel large distances

and superimposing the signal over a

stronger higher frequency called a

carrier signal

the carrier signal being constant takes

on the attributes of the analog signal

and it's shaped by either the phase

amplitude or the frequency the resulting

signal then has characteristics of both

the original signal and the carrier

signal that process this is called

modulation and when receiving and when

the receiving end decodes the signal by

separating these two signals the carrier

and the data

the process is called

demodulation

so again we have demodulation

which would basically

take these away from one another and

modulation which puts them together

devices that perform this operation

you've probably heard of before they're

called modems

and a modem is known for its ability to

modulate and demodulate hence the name

a modem is in effect a type of codec

which is a software or Hardware that

translates digital

to analog formats and back this is an

important thing to know for the exam a

DAC

is a digital to analog codec

and in

ADC as you guessed it is an analog to

digital codec

both of these exist in a modem

now this is it in analog terms but

digital modulation is also required

which allows the digital signal to

travel along distances and demodulation

is the representation of Digital Data in

an analog format for transmission over

those longer distances so the analog

signal has a characteristic changed to

signify the difference between logical

states of the digital signal this is a

fairly simple as digital signals again

only have two states one and zero and so

the analog waveform needs only be

changed or modulated in one way such as

the graphic here the frequency is

changed where the higher frequency

represents one bits and the lower

frequency represents zero bits in this

way I can convert this Digital Signal

into an analog one 1 in order to

transfer transfer transmit it over a

long distance now there are various

methods to modulate the digital signal

depending on what part of the analog

waveform is being changed the first one

is called ask or amplitude shift key

modulation here only the amplitude of

the wave is modulated and remember the

amplitude is the distance

between a peak or a trough in the

midpoint

and the result of this can only be one

or zero the next method is called

frequency shift key here the frequency

is modulated to only represent one or

zero as opposed to the amplitude and

remember the frequency is the amount

times we have this wave over a certain

period of time

we also have something called binary

phase shift key in which case the phase

of the wave is changed and remember the

phase would be if I have 2 next to each

other the difference between those

and then I have quadrature phase shift

keying here the phase is changed as well

but we can actually have two logical

States at a time

for instance zero zero zero one one zero

or one one this method actually allows

for data uh to be more secure when it's

transmitted so this is a more secure

method

finally there's something called

quadrature amplitude modulation and in

this case I can also have more than two

states at a time but what I'm shifting

here instead of the phase only is I'm

also Shifting the amplitude and so these

are both combined into one different

modulating wave now in order to

demodulate these once I've modulated

them

there must be a reference to

differentiate the data from the rest of

the signal now there are two digital

signal reference methods that can be

used the first reference method is

called differential demodulation

this takes the modulated and the

demodulated signals

and Compares them the output then

becomes one mod one signal which is the

data

there's also something called a

single-ended this method instead of

using two different the modulated and

the demodulated singles signals uses the

ground as a reference point and the

resultant information then becomes the

data now again if this is a little

confusing don't worry about it it's not

going to come up on the exam I just want

to cover this to give you a broad basis

outline of what we're talking about here

now while there is very good possibility

that you've probably heard of some of

these data units I'm about to mention at

one time or another it's really

important that you really understand

them in their actual quantities now

originally before computers became

household items and now nearly

ubiquitous computer Engineers came up

with these measurements of data and it

was pretty straightforward as we've

mentioned before in computer systems and

networking data is stored in binary

digits or bits and a single bit is

either a zero or a one this is the most

basic form of measurement zero one being

no power

or power

a lesser-known term but still cool

nonetheless is that two bits together

form a crumb

bits contain a nibble and a bits

together a byte that's how we got there

bits crumbs nibbles bites now depending

on the processor you have

a word would either be 16 32 or 64 bits

we generally don't see 16-bit processors

anymore so generally speaking a word is

either going to be 32 bits or 64 bits

this doesn't mean a word that you've

written on your word processor but a

unit of measurement just like byte is

now in most places

Hilo is a thousand such as kilometers

and uh in one thousand such as

kilometers means one thousand meters

while this is true in networking it

becomes slightly more complicated

because some sources Define a key a

kilobit as

1024 bits While others might Define a

kilobit as 1024 bytes

one of the reasons for this confusion is

and you can see right here how we get

that 1024

2 to the 10th bytes and one of the

confusion the reason for this confusion

of bits versus bytes is because of the

little B versus the Big B so here is a

fairly easy breakdown

that nearly anywhere you go and more

importantly on the exam is going to

allow you to have a perfect

understanding of how much data we're

actually talking about

this chart specifies how the breakdown

of binary data is mathematically

calculated and this binary is a base 2

system

and we'll talk more about that when we

get into binary and creating binary

um

uh numbers like IP addresses and why is

it base two because we only have two

options a one and a zero

which is a bit and remember eight bits

go into a byte so this chart mainly

demonstrates how that numbering system

works the magic number I really want you

to pay attention to is 10 24. that's the

number of bytes in a kilobyte the number

of kilobytes in a megabyte the number of

megabytes in a gigabyte the number

gigabytes in a terabyte so on and so

forth now you're not going to be asked

to calculate this necessarily but it's

good to know nonetheless

all right

so we just talked about a signal and

what analog means the signal being how

that data is sent modified and received

and then analog being that it can have

many different values

we looked at the attributes of a analog

signal including amplitude

Peak a trough

frequency and so on

we also looked at a digital signal and

Digital Data Transmissions remembering

that a digital signal can only have

generally two values a one and a zero

and depending on whether we're comparing

it to each its own or to the ground we

have different digital data transmission

methods we also looked at modulating

which allows us to send a signal over a

more powerful carrier signal

in order to allow it to travel long

distances

we looked at Digital Signal modulation

techniques perhaps we got a little too

involved in it

and we talked about how then we can

convert these Digital Signal into a

analog signal for sending over data and

then how we demodulate it back and we

talked about the device doing this is

called a modem which modulates and

demodulates

we also described Digital Signal

referencing methods in other words how

it knows where the signal begins and

where it ends

finally we described the Digital Data

units specifically I wanted you to pay

attention to the fact that one bit

equals the fact that 8 Bits equal one

byte

and the fact that 10

1024 bits

are in one

kilobit

or 1024 bytes are in one kilobyte

[Music]

Network protocols and services

common Network ports and protocols

all right now we start getting into what

I think is the fun stuff in this network

plus exam in some ways it's also where a

blue bulk of the questions are going to

come from by the end of this module

you're going to be able to say what each

of these numbers represents in terms of

a protocol now if you took the a plus

exam and I hope you did you probably

recall some of these from there so this

might be a bit of a recap for you but

that's okay it never hurts to go over

this stuff again especially because it

just always pops up on the exam and as

far as knowing stuff this is one of

those things that you just have to know

these these Protocols are what you

really have to know we're going to talk

about the protocols in more depth later

too when we talk about what tcpip is but

I want to start talking about these now

since a port is really the end point

logically of a connection

so we're going to start by talking about

what a port is in a little more detail

and outline the different port ranges

there are three of them well-known ports

registered ports and then the last range

which is

um

experimental sort of ports and private

ports so we're going to outline the most

common well-known default ports and the

protocols that go along with them I'm

actually going to give you a huge list

of all the protocols you need to know

and we're going to talk about some of

those in depth in this module some in

the next module and then some later on

in the course but I'm going to get them

all out onto a a chart for you right now

finally I wanted to find and describe

the common ports and protocols dealing

with FTP or the file transfer protocol

ntp or the network time protocol

SMTP the simple mail transfer protocol

POP3 or the post office protocol the uh

used to receive email as opposed to SMTP

which is used to send email IMAP which

is also used for receiving or accessing

email which stands for the internet

message access protocol

nntp or the network news transfer

protocol uh something you may have used

if you've ever used RSS feeds HTTP or

the hypertext transfer protocol and

https which is the secure version these

are what allow you to browse on the

internet and finally we'll talk about

RDP or the remote desktop protocol which

allows you to remote in to a Microsoft

computer all right so let's talk about

these in more depth first off we have to

define a port in computers and

networking a port is a process specific

or application specific designation that

serves as a communication endpoint in

the computer's operating system meaning

where the communication logically ends

once it reaches the user the port

identifies specific processes and

applications and denotes the path that

they take through the network

now the internet assigned numbers

Authority or the i a n a

is the governing entity that regulates

all of these Port assignments and also

defines the numbers or the numbering

convention that they're given now these

ports range from 1 to over 65 000. Port

0 is reserved and it's never used so

don't really worry about that now within

this range we actually have three

different subsets of ranges and as

administrators knowing the common ports

is crucial to managing a successful

Network

the common ports are some of the

guaranteed few questions that I I know

you're going to have on the network plus

examination and nearly every other

network examination as well so covering

these and committing these to memory is

of the utmost importance now within that

range from 1 to over 65 000 there are

three recognized blocks or subsets of

ports the first block is considered the

well-known ports these ports range from

one to one thousand twenty three this is

where we're mostly going to look at

ports uh when we look at them in just a

minute

these are used by Common services and

are pretty much known by just about

everyone in the field

now the next range of ports is called

the registered ports range these span

from 1024 to 49

151. these are reserved by applications

and programs that register with the Iana

an example might be for instance

Skype

which registers and utilizes Port I

think

23399 as its default protocol don't

worry about that but if you're curious

for your firewall's sake this is the

port I believe Skype uses

finally we have the dynamic or the

private Port range this is everything

else 49 152 to 65 535. these are used by

unregistered services in uh test

settings and also for temporary

connections you can't register these

with the Ina they're just left open for

anyone to use for whatever purposes you

may need them

so now let's talk about the well-known

default ports you need to know for the

exam this chart is really what you

should commit to memory since uh and

when you get to the test you want to be

able to basically recreate this chart

before you sit down and take the test

you'll be able to do this in what's

called a brain dump sheet so let's talk

about the first portion of these ports

we need to know the first is Port 7.

this is for the icmp echo request or

ping if you've ever pinged something

from the command line this is what we're

talking about we'll talk more about this

a little bit later

next we have Port 20 and 21. these are

for the FTP or file transfer protocol

which allows you to transfer files over

a network we'll talk more about this in

just a minute

Port 22 is for the secure shell or SSH

and Port 23 is for telnet both of those

we're going to discuss later on in a

different module but they're sort of

allowing you to remote in and control a

remote computer albeit not from a

graphical standpoint

Port 25 is the SMTP or simple mail

transfer protocol which allows you to

receive email and DNS or the domain name

service which uses Port 53 is what

allows you to transmit or to translate

say google.com into its IP address when

you're browsing out on the internet this

is a really important protocol and we'll

talk more about it later along with the

the DNS sort of server

Port 67 and 68 are for what are called

DHCP and boot P or the bootstrap service

for servers and client respectively

one for uh servers and one for clients

as we can see

right here

we're going to Define and describe those

in more detail in the next lesson

now Port 69 is the trivial file transfer

protocol this is related to the file

transfer protocol we mentioned up here

but it is Trivial meaning that it is not

a connection oriented and doesn't really

guarantee that the file has been

transferred

Port 123 is the network time protocol

which keeps the clock on a network or on

computers on the network up to sync a

great way to remember this is that time

is always counting one two three

uh Port 110 is for the pop three or the

post office protocol which is how many

of us download our email onto our local

device

and then Port 137 is the net bios naming

service this is similar to DNS but is

specific to Windows operating systems or

Microsoft operating systems

related to pop 3 is Port 143 which is

IMAP the internet message access

protocol this is another way of

accessing and managing your email let's

continue taking a look at a few more

protocols that are equally important

the first is the simple Network

management protocol which allows you to

manage devices on network Say by getting

error messages from your printer or from

a router this uses Port 161. we'll

discuss this a lot more in detail later

as well

port 389 is the lightweight directory

access protocol this is what allows a

Windows server to have usernames and

passwords

Port 443 is https or the hypertext

transfer protocol over secure socket

layer notice the S here this is what

allows us to browse the internet but

securely

we also have Port 500 which is ipsec

this one also has another name which

stands for Internet Security Association

and Key Management protocol basically

ipsec or IP security is what allows us

to have secure connections over IP

finally we're going into RDP or the

remote desktop protocol which allows us

to remotely access a computer Windows

based specifically

Port 119 or the network news transfer

protocol which is not only used with

Usenet a sort of Message Board that's

been around for a very long time but

also RSS feeds which you might be more

familiar with and finally Port 80 is

HTTP or hypertext transfer protocol the

other thing to know about HTTP is it has

an alternate Port of 8080 so you might

see either one of these on there

all right now I know that was a lot of

information I just threw out there but

we're going to cover these all in a

little more depth as we go through here

and I just wanted to lay them out in a

very simple

chart-based way so that you could commit

them to Memory

now let's talk about these in a little

more depth understand how they function

and why first up is the file transfer

protocol or FTP this protocol enables

the transfer of files between a user's

computer and a remote host

using the file transfer protocol or FTP

you can view change search for upload or

download files now where while this

sounds really great as a way to access

files remotely it has a few

considerations that need to be kept in

mind the first is that FTP by itself is

very unsecure and an FTP Daemon which is

a Unix term for a service

has to be running on the remote computer

in order for this to work you might also

have to have an FTP utility or client on

the client computer in order for you to

have this protocol operate effectively

and for you to be able to use it now

trivial FTP is the simple version of FTP

and does not support error correction

and doesn't guarantee that a file is

actually getting where it needs to it's

typically not really used in many actual

file transfer settings now just as I

just mentioned you might need a client

FTP uh software on your computer

generally speaking there is a command

line prompt that you can use

it goes like this FTP

space the fully qualified domain name

for instance google.com FTP which I

don't think is the actual one or the IP

address of the remote host you only need

one or the other if you provide the IP

address you're sort of using the direct

route if you're using What's called the

fully qualified domain name which we'll

talk about a little bit later then you

allow something called DNS or the domain

name service

to do the translation into uh a IP

address for you remember again that FTP

uses ports 20

and 21 by default

next is the simple mail transfer

protocol or SMTP

this is used to manage the formatting

and sending of email messages

specifically we're looking here at

outgoing email

using a method called store and forward

SMTP can hold on to a message until the

recipient comes online this is why it's

used over unreliable wide area network

links once the device comes online it

hands the message off to the server the

SMTP message has several things

including a header

that contains Source information as to

where it's coming from and it also has

destination information as to where it's

going

of course there's also content

information which is inside of the

packet

the default port for SMTP is Port 25

although sometimes you might see it use

port 587 which is uh by relay I wouldn't

worry too much about that one for the

exam but just keep in mind Port 25. now

like SMTP POP3 is a protocol that's used

in handling email messages and POP3

stands for the Post Office protocol

version 3 which is the commonly used

version now

specifically POP3 is used for the

receipt of email or incoming email and

it does this by retrieving email

messages from a mail server it's

designed to pull the messages down and

then once it does that the server

deletes the message on the server Source

by default although you can change that

if an administrator wants to this makes

POP3 not as desirable and weaker than

most some other mail protocols

specifically IMAP which we're going to

see because it puts all of the brunt of

the responsibility onto the client for

storing and managing emails and deletes

all the emails at the source so if

something happens to your computer and

you don't have a backup you're in big

trouble

the default port for POP3 as we

mentioned is Port 110. so remember Port

110 is POP3 and Port 25 is SMTP now IMAP

4 usually just called IMAP is the

internet message access protocol and

it's similar to POP3 in that it's also

utilized for incoming mail or mail

retrieval but in nearly every way IMAP

surpasses POP3 it's a much more powerful

protocol because it offers more benefits

like easier mailbox management more

granular search capabilities and so on

with IMAP users can search through

messages by keywords and choose which

messages they want to download they can

also leave IMAP messages on the server

and still work with them as though

they're on the local computer

so it seems that the two are synced

together perfectly the server and the

client

also an email message with say a

multimedia file can be partially

downloaded to save bandwidth

now the main benefit here is we're going

to use this instead of first say a

computer let's say I have a smartphone

and a computer now it's going to make

sure because the source is all stored at

the server

that if I delete something say on my

computer that syncs up to the server and

then the server will have that sync with

this my smartphone so all of these are

in perfect synchronization this is why

it's much stronger than POP3 which

simply downloads the email onto your

client device

by default IMAP uses Port 143 which is

different from IMAP

POP3 rather which uses 110.

now ntp or the network time protocol is

an Internet Protocol that synchronizes

system Clocks by exchanging time signals

between a client and a Master Clock

server the computers are constantly

running this in the background and this

protocol will send requests to the

server to obtain accurate time updates

up to the millisecond this time is

checked against the U.S Naval

Observatory Master Clock or atomic clock

so the timestamps on the received

updates are verified with this Master

Clock server which is again that US

Naval server

and the computers then update their time

accordingly

the port this uses is Port 123 which is

as easy to remember as time

keeps moving up one two three

now if we add an additional n to the

previous one we get What's called the

network news transfer protocol

this is very different from the network

time protocol it's used for the

retrieval and posting of news group

messages or bulletin messages to the

Usenet which is a worldwide bulletin

board that's been around since the 1980s

really since the internet was in its

nascent stages the network news transfer

protocol is also the protocol that RSS

feeds are based on this stands for

really

simple

syndication

basically this is where a user can

subscribe to an article web page blog or

something similar that uses this

protocol and when an update is made to

that page or to that article the

subscriber is updated

so in this way you can get updated

articles from your favorite web page

just like you would new

emails with nntp however only postings

and articles that are new or updated are

submitted and retrieved from the server

slightly different from RSS but RSS is

based on nntp the default port for this

is port 119.

so we're covering a lot of different

numbers here it's really important

perhaps even more than memorizing uh

specifically what each protocol does

that you definitely memorize which Port

it's a part of if you can memorize by

the way the number

and what the acronym means you should be

fine now a protocol you use every day

even if you don't realize it is HTTP or

the hypertext transfer protocol this is

used to view unsecure web pages and

allows users to connect to and

communicate with web servers although

HTTP is going to define the transmission

and the format of messages and the

actions taken by web servers when users

interact with it HTTP is what we call a

stateless protocol meaning that it may

be difficult to get a lot of intelligent

interactive responses to the information

if you remember ever making very basic

web pages using HTML or the hypertext

markup language the language that HTTP

is reading then you probably know this

so if you want more interactive web page

Pages or interaction with web pages then

you're going to use different add-ons

such as ActiveX that you might have

heard of

HTTP defaults Port is Port 80 and a

common alternate port for it is Port

8080. now similar to http is https

or hypertext transfer protocol over SSL

which is the secure socket layer this is

a secure version of HTTP so if you ever

see an s on the end of just about any

protocol you can bet that that has to do

with this being secure and it creates

secure connections between your browser

and the web server it does this using

SSL or the secure

sockets

layer

we're going to discuss the secure

sockets layer when we discuss encryption

more detail in a future lesson

now most web pages support https and

it's recommended that you use it over

HTTP almost every time you're able to

the way you do this is simply by using

instead of HTTP colon slash slash

facebook.com just put an S in front

yes Facebook supports this as do other

social media sites and even email and

even Google supports https why would you

want to do this well say someone is

browsing and or listening in to your

Google searches that might be

information you don't want someone else

to know

just as a recommendation absolutely

anytime you visit any website but

especially Financial uh institutions

such as your bank or your credit union

you want to ensure that in the bar it

says https if it's not then opening

anything in this including typing in

your bank password could be really

serious

the same goes for anything when we're

dealing with credit cards for instance

buying something make sure that https

appears in the bar or in your url bar at

the top as we've mentioned before too

the default Port is Port 443

now the last port I want to discuss is

RDP or the remote desktop protocol RDP

servers are built into the Microsoft

operating system such as Windows by

default and it provides users with a

graphical user interface or a GUI

to another computer over a network

connection

so this protocol allows users to

remotely manage administer and access

network resources from another physical

location over the Internet which is

represented by the cloud there are a few

security concerns that come with

um RDP and there is potential for

certain sort of computer attacks so

there are also non-microsoft variations

available such as something called our

desktop

for Unix

which if you are going to be doing a lot

of remoting you might want to look into

RDP by the way uses default Port

3389 although you can change that

usually as well when we're using RDP

we're also going to use it over what's

called a VPN or virtual private Network

which creates a tunnel

through which your connection occurs

this improves the security we were just

talking about so let's review what we've

just talked about first we talked about

a port being The Logical endpoint of a

connection

and then we outlined the port ranges

remember we had the well-known ports

the registered ports

and then the dynamic

or private or experimental ports what we

really want to uh learn for ourselves

are the well-known ports

I then outlined the most common

well-known default ports and their

protocols you want to memorize this

table

for the network plus exam

I guarantee you doing that will get you

a bunch of questions on the exam

finally we Define to describe some of

the specific ports and not only and we

looked not only at the protocol

and their protocols including FTP or the

file transfer protocol

ntp or the network

time protocol

SMTP or the simple mail

transfer

protocol

POP3 or the

post

office protocol

we also looked at

IMAP the internet

message access protocol and again all

three of these

have to do with email

we also looked at an ntp which is not

Network time protocol but the network

news transfer

protocol

we looked at two different versions of

HTTP one that is secure these allow for

browsing

and it stands for the hyper text

transfer protocol

which if you know HTML or the hypertext

markup language then that might be

familiar to you and finally looked at

RDP or the remote desktop protocol

I know this seems like a lot but I

guarantee memorizing all of these and

all of the numbers that they're

associated with is gonna help you so

much on the exam

[Music]

Network protocols and services

interoperability services

this word interoperability is a really

long one but it's also a good one

basically what this means is how

different types of operating systems and

computers can communicate with one

another over a similar Network and

that's what we're going to be discussing

in this module

so we're going to first cover what

interoperability services are in a

little more depth then we're going to

Define some specific services that

qualify as these particularly NFS or the

network

file system I'm sure you can imagine

what that is from its name we're also

going to look at SSH which is the secure

shell

and SCP secure

copy protocol remember every time we see

that s we want to think uh secure

security that's a great tip that'll help

you out on the test by the way secure

copy protocols similar to SFTP or the

secure file transfer protocol

we're then going to look at telnet or

the Telecommunications Network and SMB

or the server messenger block

which is what allows us to share for

instance files and printers

we're also going to look at ldap or

lightweight directory access protocol

and that word directory is important as

it allows us to manage users in our

Network

mm zero conf in networking which also

stands for zero configuration networking

a set of protocols that allows us to

sort of plug in and go

without having to do a lot of advanced

configuration and setup this is what

allows us to have very easy Plug and

Play network devices such as our Soho

routers which is a good way to think

about it however it's also deployed in

much larger operations in order to ease

the burden on administrators and

technicians

so in the previous module we discussed

several different protocols that were

used in the tcpip protocol suite and

these allowed us to do a lot of

different things by the way tcpip which

is what basically allows us to

communicate over the network in general

is going to be discussed in more detail

in depth later on in this course

now because not all computers are made

the same or by the same people or

individuals certain protocols and

services need to be in place to allow

dissimilar systems such as PCS and Macs

to be able to interact with one another

so tcpip also contains these

interoperability services that allow

dissimilar services or systems to share

resources and communicate efficiently

and securely which is important if I

want to make sure that no one is reading

all of the information I'm sending

between computers so these Services is

what we're going to spend the rest of

this module discussing

now the first service is the network

file system

it's an application that allows users to

remotely access resources and files a

resource being for instance a printer

and a file being like a Word document as

though they were located on a local

machine even though they're someplace

else

this service is used for systems that

are typically not the same such as Unix

which is the larger version or the

commercial version of Linux and

Microsoft systems now NFS functions

independently of the operating system

the computer system it's installed on

and the network architecture this means

that NFS is going to perform its

functions regardless of where it's

installed and since it's what we call an

open standard

it allows anyone to implement it

it also listens on Port 2049 by default

but I wouldn't worry about memorizing

that for the test

next SSH or the secure shell is one of

the preferred session initiating

programs that allows us to connect to a

remote computer

it creates a secure Connection by using

strong authentication mechanisms and it

lets users log on to remote computers

with different systems independent of

the type of system you're currently on

with SSH the secure shell the entire

connection is encrypted including the

password and the login session

it's all compatible with a lot of

different systems including Linux Macs

and PCs and so on now there are actually

two different versions of secure show

ssh1

and ssh2

these two versions are not compatible

with one another which is important to

know

because they each encrypt different

parts of the data packet and they employ

different types of encryption methods

which we'll talk about later however the

most important thing to know is that SSH

2 is more secure than ssh1 and so in

most cases we want to use that this is

because it does not use server Keys ssh1

doesn't which are keys that are

temporary and protect other aspects of

the encryption process it's a bit

complex and over the course of and over

the objectives of this course however

SSH 2 does contain another protocol

called SFTP

an SFTP or the secure file transfer

protocol

is a secure replacement for the unsecure

version of plain old FTP and it still

uses the same port as SSH which if you

recall is port 22.

so it's important to know that if we're

going to be using SFTP remember FTP uses

20 and 21 if we're using SFTP we're

using Port 22. now similar to SFTP is

SCP or the secure copy protocol which is

a secure method of copying files between

remote devices just like FTP or SFTP it

utilizes the same Portis SSH just like

SFTP and it's compatible with a lot of

different operating systems to implement

SCP you can initiate it via a command

line utility that uses either SCP or

SFTP to perform some secure copying the

important thing here to know for the

network plus exam is not when you would

use SCP over SFTP which is a little bit

more complex but rather to realize that

SCP is a secure method of copying as is

as FTP that's how you're going to see

this pop up on the exam now in contrast

to all of this secure Communications I

want to talk about telnet or the

Telecommunications Network which is a

terminal emulations protocol what this

means is that it's only simulating a

session on the machine it is being

initiated on when you connect to a

machine via a terminal by using telnet

the machine is translating your

keystrokes into instructions that the

Remote device understands and it

displays those instructions and the

responses back to you in a graphical or

command line manner

telnet is an unsecure protocol which is

why we don't use it as much as SSH

anymore and this is important to keep in

mind

so when you send the password over

telnet it's actually in what we call

plain text

whereas as we mentioned with SSH it

transmits the password encrypted so if

someone is reading the packets that are

going back and forth they won't be able

to hack your system if you're using SSH

whereas with telnet they'd be able to

read your password now telnet uses Port

23 by default which is important to know

however you could configure it to use

another Port as long as the remote

machine is also configured to use that

same port with telnet you can actually

connect to any host that's running the

telnet service or Daemon which again the

word Daemon is a Unix version of service

SMB or the server message block which by

the way is also known as cifs or the

common internet file system is a

protocol that's mainly used to provide

shared access to files peripheral

devices like printers most most of the

time

and also access to serial ports and

other communication between nodes on a

network Windows systems used SMB

primarily before the introduction of

something called uh active directories

which we'll talk more about a little bit

later this is currently what's used in

Microsoft networks now Windows services

that correspond are called server

services for the server component and

workstation services for the client

component

now for example the primary

functionality that SMB is typically most

known for is when client computers want

to access files systems or printers on a

shared network or server this is when

SMB is most often used

Samba which you may have seen if you've

ever dealt with a Mac or a Linux

computer is free software that's a

re-implementation of the SMB or cifs

networking protocol for other systems

even though SMB is primarily used or was

primarily used with Microsoft systems

there are still other products that use

SMB for file sharing in different

operating systems which is why it's

important that we still familiarize

ourselves with it

ldap stands for the lightweight

directory access protocol and this is

what defines how a user can access files

resources or share directory data and

perform operations on a server in a

tcpip network now this is not how they

access it this simply defines how a user

can access it meaning that we're really

talking about here are users

and permissions

so basically ldap is the protocol that

controls how users manage directory

information such as data about users

devices permissions searching and other

tasks in most networks we're going to

deal with this a little more in depth

later on as well now it was designed to

be used on the internet and it relies

heavily on DNS the domain name service

which we talked about is a way of

converting say google.com into its IP

address we're going to discuss DNS in

Greater detail in another module now

Microsoft's active directory service

which we just mentioned and novell's NDS

and e-directory services Novell being

another networking operating system as

well as Apple's open directory directory

system all use ldap now the reason it's

called like lightweight is because it

was not as Network intensive as its

predecessor which was simply the

directory access Protocol no need to

know that but I just wanted to explain

the reasoning behind that light weight

in there

also it's important to know that port

389 is used by default for all the

communication of the requests for

information and objects finally zero

conf or zero configuration

networking is a set of standards that

was established to allow users the

ability to have network connectivity out

of the box or Plug and Play or without

the need for any sort of technical

change or configuration zero con capable

protocols will generally use Mac

addresses or the physical addresses as

they are unique to each device with a

NIC or network interface card

in order for devices

to fit into a zero conf standard they

have to fit or meet four qualifications

or functions first the network address

assignment must be automatic if you

recall from a plus and this is something

we'll talk about a bit later this is

what we use when we're using DHCP

second automatic multicast address

assignment must be implemented which is

also related to the DHCP standard third

automatic translation between Network

names and addresses must exist this is

what we talk about when we deal with DNS

finally discovery of Network Services or

the location by the protocol and the

name is required meaning that it must be

able to find all of this information

when it goes on the network

automatically this is what allows users

to be able to purchase a router from the

local Best Buy or electronics store take

it home plug it into their ISB or

Internet service provider connection and

automatically have it work automatically

another implementation by the way of

this is a configuration and networking

called

you PNP

or

Universal

plug

and play

so to recap what we've talked about we

talked about interoperability Services

which allows for instance a PC and a Mac

to communicate flawlessly over a network

we then talked about the network file

service

SSH and SCP SSH being a secure shell

working on

Port 22

and SCP being the secure

copy protocol

similar

to

SFTP the secure file transfer protocol

we looked at telnet which is sort of a

plain text version of SSH so it's been

replaced by it and SMB or the server

message block allowing us to share files

and resources

between different types of systems

finally we described and defined ldap or

the lightweight directory access

protocol which defines users and their

ability to access all this stuff on the

network and then we explained zero conf

or zero configuration in networking

which allows us to plug up a device and

have it work almost instantaneously

[Music]

thank you

welcome to module 5 lesson 1 ethernet

standards pretty meaty subject this

because it's got a whole bunch of

standards and information as well as

history to fit in

what is ethernet the history why the

name just in case you wanted to know I

guess

introduction of ethernet standards

the Archer Police standard as well ATO

2.3 which you'll need to be familiar

with which defines ethernet

the IEEE as well what they do and their

remit per view

uh based on a Broadband some history

really of the early days of ethernet

networking

which are depending on how old you are

you may be familiar with

some of the naming conventions uh the

early days the early specifications

thick nets in net

and some of the standards here which

we're going to run through which you'll

need to be familiar with because you

could be asked a question

so that's a good reason as any uh

ethernet it's the was or is the first

high-speed land technology that in

Connected computers high speed Laser

Printers obviously in the early days

there needed to be some agreed format

for um Internet working devices to

communicate

actually invented by a guy called Bob

Metcalfe back in

1973. it was remarkable in as much that

at the time competing was dominated by

some very large and expensive mainframe

computers

um to name IBM as a one of the main

players at the time

it's only a few people could actually

afford to buy the mainframes and the

information required in order to use

them operate support and maintain was

only known to a few people at the time

so Bob actually changed the name of his

first network from alto Alor Network to

ethernet thankfully otherwise would all

be referred to it as alto Aloha which um

be a bit strange

why the name he um Bob's experimental

Network the physical medium

or the cable to carry out all the bits

to describe the important feature Bob

named the network based on the word

ether

the old um luminous lumini Ferrera

Ferris ether was once considered the

medium for the propagation of

electromagnetic waves

so there are some mythical background in

it

and first standardized by the Consortium

of deck Intel Xerox or Dix

later actually standardized by the IEEE

standards defined several aspects that

make data transmission possible this is

their job

term ethernet is used to refer to both

the original Dix ethernet which we'll

rarely talk about unless we're doing and

talking in the context of exams and the

802.3 specification which specifies

ethernet old and new

so 802.3 is an international standard

for local area networks and metropolitan

area networks that employs the carrier

sensor multiple access with Collision

detection

the ethernet protocol frame format for

communication

the IEEE is the institute for electrical

and electronic engineers

uh largest Professional Association

um for the advancement of Technology

it has more than uh 400 000 members

spanning 100 and more than 160 countries

so what do they do

they provide Society Publications they

develop on new and emerging technology

standards they also have conferences

that various Network Engineers can

attend to swap ideas and Advance the

technology

uh fortunately I'm not um this the

points aren't sliding in as they should

be so um all the information is

appearing at the same time sorry

so the ieee's leading developer of

international standards they include the

802 standards which are for lands and

mans and wireless local area networks

also which will refer to usually as

Wi-Fi you'll see the little stickers on

Wi-Fi devices and when you go to cafes

they may well have a Wi-Fi sticker to

say them they give a wireless access

and so ethernet's the most popular today

it's everywhere basically making

communication possible for pretty much

everyone and mainly popular because of

um the fact is economical to use it uses

high speed it's reliable and it's easy

to install and maintain also free to use

the standards

um like TCP if you used a custom

Solution by another

um Creator then you'd obviously have to

pay to use all of their

um specifications and standards

so the early ethernet run over what was

known as coaxial cables

um modern ethernet don't do that anymore

because of the limitations of speed and

troubleshooting they use a mixture of

copper and fiber depending on um the

location and how much what the budgets

of the various devices or

um local government authorities have

based on broadband is the term

synonymous with ethernet the band is

actually referred to the bandwidth in

context of the transmission

uh Broadband is a broadband system a

whole band of transmission medium is

shared dividing it into pieces called

channels

each channel will have the portion of

the whole band multiple channels will

serve as multiple signal carriers each

carrying its own data on the same

transmission medium so basically we're

all sharing the same medium and the

local ratio I think for my Broadband

here is

um 30 to 1 so 30 users will use one

connection to the local

um switch provided by the telephone

company

base band in the baseband system the

entire band of the transmission medium

will be used as a signal carrier

naming conventions the ethernet

standards username and Convention that

houses determine a few things the speed

of the transmission the signaling type

and the length of the cable

uh cable type used as well for example

10 base 5 really old standard this it

was been phased out in the well late 90s

I think when I was

um just getting into networking really

so 10 base 5 is named for the following

10 is the transmission speed which is 10

Meg

base means the type of signal in his

baseband and five indicates to the track

the maximum length of the cable can be

up to 500 meters

this is for the segments you could have

another segment after 500 meters

and the signal would all have to be a

replenished

okay so a thousand Base TX the following

is true a thousand indicates uh sorry

100 htx 100 is the speed which is 100

mag

base stands for baseband again T

indicates that the standard is twisted

pair

X at the end indicates that the K the

cable is capable of full duplex

communication

10 base 5 real old standard again

um based on 802.3

the original standard uses a thick

coaxial cable as its physical medium it

was actually called thick net for short

and you can see the picture of it there

to actually connecting to the cable use

these big plastic devices uh called um

vampire Taps and they're physically

screwed in to the cable and pierced it

very awkward to use and hard to

troubleshoot it ran at 10 Meg

and either RGA or rg11 it had a little

resistors on the end to stop the signal

bouncing off the back of the cable and

coming back and they ran at 50 ohm RG

stands for radio government

standard determ is a type of coaxial

cables the distance was up to 500 meters

there were a few pros and cons to using

thick net

you have protection against

electromagnetic interference which can

seriously degrade your signal

disadvantage there was loads actually

difficult to work with very difficult to

troubleshoot cable was very thick so

trying to expand it around an office

without

and people tripping over or hitting the

head off them was quite awkward as well

thin net is based on the 10 base 2

standard

so 10 Meg

um

baseband and two stands for how long the

and you could get the connection which

is 200 meters

was actually 185 was recommended but you

couldn't you couldn't ensure to 185 so

they called it 10 base 2.

uh being cheaper than thick Navy was

called cheaper net

before we had any type of network and we

used to use floppy disks

big thick floppy disks not even the

small ones that you might remember that

was called sneakinet

turnbass tea was one of the first modern

standards introduced in 1990

it ran over 10 Meg over two pairs of

twisted uh paired telephone wire

and it allowed your network to use the

existing telephone cabling which is

pretty handy really easy to install

reduce costs the cable could just be run

off and you could cut it to whichever

length you required

and also obviously you could use a

network switch which the uh thick and

thin that couldn't use a switch or hub

T denotes twisted pair wires

10 base T is category three cable we

used to call it cat 3 for short in fact

every category is is called a cat for um

short

High category cables can be used with

the 10 base T ethernet

so examples are CAT5 5e 6 6A and so on

this changes every few months as a new

category introduced

High categories of the TP cables have

higher specifications and they can

handle higher data transmission speeds

the term base T supports the maximum

cable length of 100 meters

100 Base TX I mentioned earlier

100 Meg over two pairs of CAT5 twisted

pair cable in you can get 100 meters

before you have to terminate the cable

we normally then go into a switch

it's called Fast ethernet

so 100 mag obviously 10 times faster

than 10 base t

uh became widely used because of its

compatibility with 10 base T so imagine

back in the day you would have your um

the core of your network running at 100

Meg and then um unless if you didn't

have the budget you would have your

individual PCS connecting at 10 Meg into

the network switch or hub

they used a Cat5 cables a lot easier to

upgrade because it used the same Cable

in principles and same pin outs

and determination

100 base FX f is usually designates

fiber optic

fiber standard for 100 Meg ethernet is

100 base FX

so this is a

802.3 u specification

it's 100 Meg ethernet over two

multi-mode Optical fibers

one's used for the transmission and ones

used for the receiver as and designated

in the diagram there

the 100 base FX standard supports the

maximum cable length of 400 meters in

half duplex mode

half duplex is pretty old-fashioned now

to be honest

or in full duplex mode

which means you can send and receive at

the same time then up to two kilometers

half duplex mode as well just so

basically it's like a walkie-talk here

device can either send or receive data

at a given time but it can't do both

full duplexy can do both so it's like

having a telephone conversation

a thousand base T now we're talking 10

times faster than a hundred

it's a IEEE 802.3 a b specification it's

a thousand megabit per second ethernet

Network uses four pairs of CAT5 cable or

better

and speak to your cabling provider to um

find out what cable you can use minimum

standards

100 meter length of cable

it's um referred to as gigabit Ethernet

1000 bits

that easy to install runs on CAT5

and inexpensive cables

as an example of a CAT5 cable which I'm

sure you've seen many times even if

you've got a home computer

so the Cat5 cables are four pairs of

twist uh four pairs of Twisted wire

which is eight individual strands

the 10 and 100 base T only uses two

pairs

all four pairs are used by the EM

thousand base t

popular gigabit Ethernet and the

Thousand base T is the most widely used

version

you've got the a223 standard that

specifies other versions of gigabit

Ethernet here are some of your options

um thousand Bay CX LS LX

SX

uh you need to know some of this

information but I think one of the

questions they could ask is which one of

them is

um fiber optic and the answer is LX it's

a question I've seen before I think I

was actually asked in a Cisco exam not

um uh CompTIA Network plus but good to

know anyway

so five kilometers to 550 meters

depending if it's single or multi-mode

and SX is implemented over multi-mode

fiber as well so um LX and SX

1000 Base TX is gigabit over Cat6

cabling

supports a maximum cable length of 100

meters

uh uses only two pairs of wires for the

data transmission

now the Thousand Base TX you don't

really see much anymore is a bit of a

commercial failure

mainly because of the Thousand base T

the cost was so affordable you had to

upgrade all of your cables from CAT5 or

Cat5e to Cat6 which is a lot of

inconvenience and expensive companies

and downtime

because of your all your core devices

would need the connections would need to

be um changed as well normally have to

schedule downtime

um for this

10 gigabyte 10g base t 10 times faster

than a thousand base T ethernet operates

at 10 gig

and it's an 802.3 a n specification four

pairs of Cat6 a cable or higher

100 meters maximum

it's an augmented version of category

six which you can see 6A isn't the same

as six

and frequency is at 500 megahertz

next standard is 10gbase Sr this is

gigabit Ethernet over Fiber Optic Cables

I don't know why they don't just put a f

in all of the fiber specifications it's

a little bit annoying to be honest

802.3 specification

is 10 gig ethernet over multi-mode fiber

the SR stands for short range

at the cable length is 300 meters so you

only need to make a note of all of these

in case they

for some reason want you to

um remember this generally most of us

will just look speak to the sales

advisor or just look on the um online or

some documentation

10 gbase er

802.3 AE a gigabit over single mode

fiber optic cabling ER stands for

extended range you got up to full of 40

kilometers which is a quite a nice

distance amazing distance in fact

uh SW

that was designed for use over a

particular type of Technology sonnet or

sdh

again multi-mode fiber 300 meters again

all right so we've covered a few of the

basics of ethernet here the history the

name the standards uh the oee what they

do in brief

I recommend you have a look in your own

time at Wikipedia

the popularity which is nearly always

the fact it's the standards are free to

use and it's affordable and everyone

else is using the same standards

baseband the Broadband the naming

conventions and then some of the

different standards here

you'll need to know the different

standards which uses a single and

multi-mode how long um you can have a

segment that lengths and that kind of

thing

all right so that's the end of the

presentation thanks for watching

[Music]

Network infrastructure and Design

Network models the OSI model

so we're going to discuss two different

models coming up here and the first

model I want to talk about is the OSI

model in this module now from this

lesson you're going to have a thorough

understanding of each of the layers in

this module and there are seven of them

and we're also going to talk about how

those layers communicate some of the

devices that operate at specific layers

specifically layers one through three

and some of the protocols that operate

on some of these layers as well

specifically the upper layers we're also

going to have a better understanding of

what the OSI model is and why we use a

layered approach

so this model is going to teach us

everything we need to know about the OSI

model we're going to begin by explaining

exactly what the OSI model is and what

the purpose of it is as well then we're

going to go through and explain each

layer from layer 1 the physical layer to

layer 2 the data link layer later three

the network layer layer 4 transport

layer layer 5 the session layer layer 6

the presentation layer and finally layer

7 the application layer we're also going

to discuss some of the protocols and

devices that operate at each of these

layers and we're also going to

understand how communication begins and

ends through these layers now early back

in the 1980s late 70s when networking

communication between devices which a

lot simpler a lot of brilliant

individuals from the iso organization

we've seen previously or the

International Organization for

standardization came together and they

came up with a a way to outline

standardize and characterize the

functions of a communication system or

the methods by which computers are going

to communicate in a network environment

so they came up with this OSI model and

I love it because I know the iso made

the OSI and they did this in term of

abstract layers so what we mean by these

abstract layers and here they are again

from the top down application press

presentation session transport layer

data link physical and just so we don't

get confused the first layer is actually

here at the bottom and the last layer is

here at the top and that and viewing

this we call this a top

down approach as opposed to a bottom-up

approach

and these

abstract layers outline the functions of

the communications process but they hide

exactly specifically how they're

implemented in each layer in other words

this really attempts to simplify and

sometimes oversimplify exactly how

everything in the network is

communicated so let's say that we want

to establish a highway more so we really

want to build a brand new type of

vehicle designed specifically to be

driven on this very specific Highway and

we're going to have to do it from the

ground up so let's call this vehicle a

bus

not only do we want this bus to be able

to run on any of the existing highways

or they're out there but we also want

the bus to be able to use the already

existing bus stations as well so in

order to do this we need to understand

exactly what we already have meaning

what the standards are already in place

for a highway we also need to know

everything about bus stations and

everything about the infrastructure of

the highway system that already exists

regardless of whether we actually have

to build the highway

we still need to understand everything

that relates to highways and their

designs uh to the materials the

limitations and so on so this way when

we're designing our brand new bus we can

ensure that it still can drive and

operate on older highways not to mention

new highways and that our bus is going

to interact uh properly with the other

buses and other vehicles that are on the

road the other benefit here is if I'm

designing this bus and I break it down

into different layers seven of them I

only have to worry about one part for

instance there might be someone who is

responsible for say the wheels and there

might be someone else who's responsible

for uh say the body and there might be

someone else who's responsible for the

highway and someone else who's

responsible for the bus stop and so on

and so forth this way I can fragment

everything out and give everyone

specific jobs and if a problem occurs

with the bus then I can go to the

specific person who with whom who is

most familiar with that section or that

layer this is the benefit to a layered

approach to creating something

so that being said let's talk about the

very first layer layer one

so layer one is the physical layer the

this is the actual physical media the

cables the wires this is the means by

which the bits go from one point to

another so for the actual cable uh the

infrared connection the radio frequency

even Wi-Fi all of these reference the

layer or the pathway that the data is

going to take so to take a look in this

in the way that we were talking about it

with our bus and our Highway setting if

our main concern is building our buses

we need to look at all of the other

vehicles on the road we need to

understand their size their shape other

characteristics and so on so that way we

understand how our bus can use the same

tracks the other vehicles are using so

here on layer one we have the path the

road used for communication again this

is the wire the Bluetooth fiber copper

the Wi-Fi whatever means there is that

physically the bits the ones and zeros

rows are going over this media so the

terminology for the information is

considered simply the bits because we're

actually transmitting the raw one and

ones and zeros we're not dealing here

with what the information is we're

dealing with it at the most Electrical

uh basic sort of

standpoint so this is simply the mid the

median this is called physical and as

you can imagine this is also the very

first place that data is going to enter

into the computer right it goes over the

chord and into a nick

all right now what happens then

well then we get to Layer Two which is

called the data link layer an easy way

to remember that the layer 2 is data

link is because it's the only one that

has two words it also has and this is

not as important uh for

this uh for the network plus exam but

it's still good to know there are two

what we call sub-layers the max sub

layer and the LLC sub layer

this layer in total and so these two

make up

this data link layer and this layer as a

whole is responsible for allowing

devices to share the same medium the

medium being the physical layer so here

we see a few things happening first we

see a certain level of error correction

and error detection on the physical

layer we're going to see this a little

more on later layers as well

also and probably more important we see

access control which I've denoted here

and I'll get to this in a minute by the

stop light

so this function is performed by this

Max sub layer again I wouldn't worry too

much about that but the most important

thing here is that we have physical

addressing or the MAC address so

anything that looks at Mac addressing

and by the way Mac addressing is oddly

enough performed

by the LLC layer

allows a device to look at a certain

extra layer of information so whereas

with layer one we saw physical if you

remember we talked about hubs hubs just

forward bits they don't look at the bits

so they're going to operate at layer one

here at Layer Two we start dealing with

Mac addresses as a result this is where

devices like switches are found and

that's why switches are often called

layer 2 devices

there are more advanced types of

switches but I want you to remember

again a switch is a layer 2 device now

if we look at this in a slightly

different way here's where we have to be

able to have access control on our

highway so this is where we have to be

able to have uh proper on-ramps that are

only going to allow authorized vehicles

to enter onto the road and we also need

to establish standards for how the road

is going to be used by everyone perhaps

with signs and here we also remember

this is where we establish how everyone

is going to share the road who's going

to access the road and a certain level

of checking for damage on the highway

and vehicles for instance people sort of

going on and making sure there aren't

potholes in this layer we refer to the

data as frames of data because they're

beginning to get framed we're no longer

just dealing with the ones and zeros

we're dealing with them in a frame or in

a uh sort of larger context now the next

layer is layer three or the network

layer here's where a really a lot of

exciting stuff happens okay first the

third layer is different from the second

layer in that the data link layer

transfers data between devices that are

within the same network okay so if you

remember we talked with dealing with

switches switches only deal with devices

on the same network but here on layer

three the network layer can allow us to

transfer data to and from devices that

are on different networks it does this

by a specific kind of addressing

specifically

IP addressing and when we deal with IP

addressing or the Internet Protocol

we allow what's called routing

so the main job of the network layer is

really about this routing it's about

routing and routers so knowing this and

that IP addresses are used for routing

we come to the conclusion that the kinds

of devices we're really going to find in

this layer

are routers so routers are what we call

layer 3 devices and that's you're going

to see on the test now for the

information to actually reach the

destination this IP address has to be

mapped

to a physical address on layer 2.

so the protocol that does this is called

arp

what ARP does

is it Maps

for better for a lack of a better way of

describing it Maps Mac addresses

to IP addresses by the way ARP stands

for address

resolution

protocol

this protocol actually operates slightly

on the network layer and slightly on the

data link layer because obviously it's

dealing with Mac addresses and IP

addresses

now it's important that you consider

that remember we talked about

UDP

versus TCP

UDP being

connection less and TCP being connection

oriented that's when we're dealing with

ports and we'll talk about that more we

talked about that in a plus and we'll

talk about that a little more later well

everything in the network layer is

connection less

this means that it manages the transfer

of data in a connection less uh mode it

just sends the data but it's not going

to wait for a reply to ensure it got to

its destination this means we're sort of

using a best effort here this is like

dropping something in the mail and just

hoping it gets there we're not using

certified mail at all on layer 3 the

information remember Layer Two we had

frames well now we have something called

datagrams

so this is now we're moving up right we

had frames now the frames are packaged

into datagrams so if we keep with our

method of talking about the bus metaphor

okay

from the third layer up we're going to

concentrate on the bus itself so we've

been talking about the road right we

talked about the road itself the

physical layer and then we talked about

how people are going to share that road

which is Layer Two

data link layer now layer 3 the network

layer this is the bus itself layer 3

through 7 concentrates on the processes

that affect this container in our case

the bus since we're basically designing

our bus this layer is determining the

best path that our data is going to take

so in a manner of speaking this is like

the bus driver on a specific route who's

going to constantly updating us with

routing information so it's saying

here's our first destination here's our

second destination here's our third

destination just in case a route is

blocked or if there's a faster or better

route available layer 3 is where those

Protocols are going to operate to find

the shortest and most reliable path to

our destination

here on the fourth layer also called the

transport layer some crucial functions

are taking place now one of these

functions is reliability it can be said

that the TCP protocol what you might

have heard in TCP IP if IP was on the

layer 3 perhaps then layer four is TCP

the TCP portion operates on this layer

or at least close enough to the

transport layer to be considered a layer

4 Protocol

just to sort of secondary side note and

we'll talk about TCP and IP a little bit

more in depth in the next module they

have their own model the OSI model is

sort of a theoretical model it was never

actually implemented as it was created

that being said we still use it in

discussing a lot of stuff which is why

we need to talk about so the reliability

is guaranteed by in here the connection

oriented

protocols that are on layer four

so the transport layer has mechanisms

that keep track of uh these segments and

when segments fail the transport layer

resends them there's also this

acknowledgment feature such as a like a

certified letter would have that ensures

that when a message is received by the

destination the transport layer is

notified for instance by a message

received successfully what we call a ack

packet or acknowledgment packet

besides these guaranteed delivery

features we also have what's called data

flow control this function ensures that

during the data transfer the receiving

end doesn't get flooded with too much

data at any one time later in the lesson

we're going to talk about different data

flow

techniques and flow control techniques

that are used the transport layer is

where something else called sequencing

of data occurs basically when data is

transmitted it's either broken apart or

fragmented to be able to send it across

the medium and when it's fragmented each

fragment or piece is labeled with a

specific number so that when the

receiving end receives uh when the

receiving end of the transport layer

receives this data it can be reassembled

and put back together in the proper

order this is really important

especially when data is received out of

order as I just demonstrated now in

essence this layer is much like the

standards and the laws that we have in

place on our highways they ensure that

Vehicles get us to where we need to be

safely and on time now some of the other

protocols you may have heard of that

operate on this layer are sctp uh some

tunneling protocols and uh more

importantly here when data is sort of

partitioned out it's called a segment as

opposed to a datagram or a frame now the

next layer is uh I think it's one of the

easier ones to memorize it's called the

session layer and layer five and it's

pretty simple because the sole purpose

of this layer is to establish maintain

when it comes time to shut down or

conclude the communication session now

while the OSI model assigns the

responsibility of this termination of

sessions to the session layer some other

models have performed this on a

different layer and we'll talk about

that a little bit more some of the

protocols you might see on here are for

instance RPC which stands for remote

procedure call and

TLS and SSL as well so this layer

manages how and for how long and what

way a device is going to establish a

connection during the communications

process that the layer is not yet

completed with its functions the rest of

the network just has to wait

so in keeping with the analogy of the

boss in order to understand how the

session layer fits in let's take a look

at exactly why we're using our buses is

it for transporting people or is it for

transporting top secret documents from

the main office building to the remote

office this Y is going to determine

several things for this layer right if

it's determined that we need

um

several connections to take a private

Highway for instance it might be

determined that we need a private bus to

take

um

special documents

to maintain security or take a special

Highway for instance so the session

layer is what's responsible for

determining what type of data and how we

need to connect this session continuing

on to the next layer is the presentation

layer or layer six this layer is

responsible for taking the data from the

application layer which is the next

layer we'll talk about and translating

it into an intermediary language that

the rest of the network can understand

and it's also going to perform it in

reverse on the receiving end also in

this layer data encryption and

compression takes place sometimes called

the syntax layer because of its data

encryption abilities as well as its

conversion to a network relatable format

or a format that applications can

understand now what this really means is

because the applications is going to

have its own syntax or its own language

the presentation layer is going to try

to a map between those languages now if

the mapping is available

then the presentation layer is going to

convert the data into Data units for the

session protocol and after that it's

send down the stack down the rest of the

layers to do everything else it needs to

do some of the protocols that operate

this layer are

anything that's dealing with compression

for instance PNG jpegs

Tiff a lot of these sort of picture

file extension that you've seen this

layer also performs code conversions

they're going to take raw application

data and compress them into more

manageable forms for transmitting now

regarding the translation capabilities

of this layer think of like two

different systems that are very

different from each other one perhaps

using TCP which we know another using

ipx SPX which you don't worry about but

it's another sort of protocol Suite this

layer is what makes Communications

available because of this we also know

that a Gateway device if you recall from

the devices we've talked about

is a device that's going to operate on

this layer

because it's converting between two

different types of Networks

this is the biggest difference between a

gateway

and a router which as you recall

operates on layer 3.

a transceiver by the way and you

remember a transceiver is that device

that is on a

Nick it's going to allow you to talk for

instance between a copper and fiber

Network also might work on this

presentation layer depending on how we

Define it other people might actually

say it works on a physical layer now to

put this layer in perspective the

presentation layer is like having a

double decker bus with a tour guide on a

microphone who's translating everything

that can be seen and heard to the

passengers the tour guide is also going

to help repack the tourists luggage for

them which is like a compression

and it's also going to add another level

of security for VIP passengers

who might come on board this is just

like

encryption

here the formatting is simply making

sure that the passengers are briefed and

ready for their tour and making sure

that they or the data is ready for the

application so again we're really

packaging this up for presentation to

the application layer and the

terminology for data at this point is

going to be actually called Data so this

is where we're moving up in the world

we're no longer talking about segments

or datagrams or frames we're here now

talking about data it's packaged in a

way that an application can read it

finally at the topmost layer we have the

application layer this is the layer

that's closest to

the user and it's the only one that the

typical end user is going to be

interacting with now even though it's

called the application layer this

doesn't mean that the application itself

is on this layer but that the

application layer provides utilities and

services that an application could use

for accessing network resources like

some of these that we've talked about

SMTP which allows you to get email DNS

which is going to translate between an

IP address and a fully qualified domain

name FTP which is going to allow for

file transferring ntp Network time

protocol which is going to keep time up

to date and HTTP which allows us to

browse so for example let's say you have

a file that you'd like to transfer to a

remote computer right what method you're

going to use FTP now the application

layer provides the FTP services to the

application you use which is some sort

of FTP client the FTP client itself does

not exist on the app application layer

simply the protocol does this layer is

the one you've probably dealt with the

most and you're probably likely already

familiar with without even realizing it

for example you utilize this layer every

time you check your email browse Etc and

so on now some of these might not fit

perfectly into the application layer and

that's because again this is a

theoretical model when we talk about the

TCP model next it will see this working

in a lot more of a practical way now

because we all know we have many

different applications on every one of

our computers one of the purpose of the

application layer is to regulate the

communications between these

applications and manage when they

request services and resources so while

it might seem easy to lump all

applications together when talking about

this layer the only applications that

this layer is actually going to manage

are those that have a Communications

component

so Solitaire would not qualify for this

right but Internet Explorer which has

all those browsing and protocols FTP DNS

Etc is going to uh deal with this so

this layer is also responsible for

network access a certain level of error

recovery and it's also capable of some

data flow measures there's a lot of

redundancy here as this is the seventh

and the final layer this is where the

information or process either starts

or finishes

so an application is going to create

what it needs to be sent here and then

unwrap the data once it's sent uh from

one computer the next so to finish off

our analogy of the bus

um this is sort of like the bus station

here's where all the people wait in line

to get tickets to use the bus they're

going to dictate the bus station is

going to dictate who has access to the

resources the resources being these

buses and it's going to receive all the

incoming drop-offs and process them as

well as control the flow of people in

and out of the station and it's going to

notify people if there are problems on

the highways and so on just as users are

typically mostly going to interact with

the application layer the bus riders are

really only going to interact at the bus

station layer right they're not going to

be interacting with mechanics and

building the bus or maintaining the bus

or dispatching individuals or any of

that stuff in most cases they're not

even going to be interacting with the

individual driving the bus so this is

really where users are going to be doing

most of their interacting now after

going through each of of these layers we

can now begin to have an understanding

on how they're grouped together

for instance layers 5 6 and 7 are what

we call application support block when

we look at each of these layers

individually we can very easily see that

the functions of each play a very

specific role in the application

management support and keeping them

consistent the remaining four layers

from the transport layer down to the

physical layer are what we call the

network support block these layers and

the protocols and devices that operate

on them are all Network related whether

it's for routing or switching on the

network or ensuring data delivery on the

network and so on perhaps even making

sure that the actual bits all the way

down to those bits of data being

communicated now as technicians and

specifically for the exam you really

want to know which layer relates to

which support blocks and also this is

going to help a great deal when we

discuss the next networking model which

is the tcpip layer model so uh just to

sort of go through this again

we start here at the application layer

and we work our way down until we get

down to the physical layer which is

where the data can actually be

transmitted

over the network and then it builds its

way back up until we get to the last

application so if I'm browsing uh let's

say this is me

right and this is a web

sort of server

I send a request the request goes down

all the way goes over the network it

might even hit a couple routers along

the way

or switches rather

so we're hitting some switches and then

we hit some routers then we had some

switches and then it's going to go all

the way up again to the web server and

then the web server is going to send

that data back Etc and so we go this

really follows on each end how data is

being sent and received so before we

wrap this up there's a couple ways to

remember these and I'd really highly

recommend committing this OSI model to

memory there's two ways we do this one

is called the top

down approach this starts with layer

seven

and ends with layer one now the reason

you want to just remember whichever

mnemonic device I'm about to tell you

just remember which one you're

remembering so that way you know how to

write it

a great way to remember this one is all

people seem to need delicious pizza

uh now again all his application starts

at seven so we're starting with the user

and we're going down to physical to the

hardware

now the other way I like to remember

this is uh please do not throw sausage

pizza away that's my particular favorite

now here we're taking a bottom

up approach because we're going from the

bottom up so realize that this you're

starting with the physical layer

and going up to the application layer so

however which one of one of these you

memorize you use to memorize this uh

just remember to commit it to memory and

when you get to your exam write it down

immediately so you can just look at it

and remember this is seven six five four

three two one this is where hubs would

function again uh they're just

forwarding the same information just

like this is where a cable would

function data link is where most

switches are going to function and on

the network layer that's where we're

going to see routers function this is

the most information that I see on the

exam and so if you Commit This to Memory

I think you'll be set

okay so just to recap one last time and

review everything we've discussed first

we explained the history and the purpose

of the OSI model remember the important

thing to realize here is that it's a

layered model and the reason it's

layered is to make it easier not only to

develop things for each layer instead of

having to develop something for the

entire system I can just develop one

little device such as a router or a

switch and also it's going to be easier

to troubleshoot and fix anything that

goes wrong

we then talked about layer one the

physical layer right and this is uh

where chords

for instance the media exists

and where all the bits are going to go

from one place to the other we're really

here dealing with the ones and zeros the

electrical bits also remember hubs exist

here as well

we then talked about the data link layer

this also had two sub-layers Mac

and LLC

and this is where we see Mac addressing

or physical addresses start to occur and

that means that here is where we're

really going to deal

with switches

the data here by the way is called is

put into what we call frames instead of

just dealing with bits

now the next layer is the network layer

and this is where we start to see

routing and this is thanks to a new

addressing system specifically the one

we're going to see the most is IP

addressing this means here is where

we're going to start seeing routers and

don't forget here we see start seeing uh

terminology for packets

and the one we mentioned too was

datagrams we also mentioned that this is

where we see connection loss

or connections that don't sort of have a

definite got sent or delivery receipt we

then looked at layer four which is where

we see TCP from the IP Suite right and

this is the one that's going to start

looking at guaranteeing our delivery

layer 4 is also where we ensure

reliability

and flow control

here information

is called segments when we get to layer

5 or the session layer we see that we're

really establishing and maintaining a

session

this is where we're going to start and

gracefully end our Communications such

as SSL Communications when we get to

layer 6 this is where encryption

and compression occur

this is also where we start seeing the

term

data

finally we talked about the application

layer

or layer seven this is the layer that's

closest to the user

and this is where you're really going to

see the interaction this is where we saw

a lot of the stuff such as SMTP

FTP

HTTP and so on

this really governs everything so if we

go back through this with our metaphor

remember the physical layer are the

highways

the date of the link layer or how we're

going to share the roads

remember we thought about a stop light

the network layer is where we start

determining the best route to get from

one place to the other

the transport layer tells us for

instance the rules of the road

the session layer is what type of

Highway we might need to take

for instance I might need to take a

um a special private Highway if I have

important documents the presentation

layer is like the bus driver

who is going to pack up our bags for us

and also communicate and make sure that

we know where we're going and the

application layer is going to be like

the bus stop

now the OSI model is in actuality pretty

obsolete but we need to understand the

theory behind it before we can get into

something that's a little more

um uh necessary for instance the tcpip

layer model

[Music]

Network infrastructure and Design

Network models the TCP model

whereas in the previous module we talked

about the OSI model A mostly theoretical

model that's in use in computer networks

in this module we're going to talk about

perhaps what is considered to be one of

the most common or at least the most

widely used model the TCP model now

while it's important that we memorize

and familiarize ourselves with the OSI

model it's also really important that we

understand this TCP model and the

differences between it and the OSI model

as technicians and administrators it's

really important that we're familiar

with each layer as well as how a data

transfers between all of these layers

and how all the protocols that are used

in TCP relate to one another and in the

layers

so

the objective of this module are first

to explain the purpose and depth of the

TCP model and to compare it in some ways

with the OSI model we're also going to

talk about what data encapsulation and

fragmentation are these are really key

to how large amounts of data are able to

be transmitted and transferred over the

Internet the largest Network in the

world

and then we're going to talk about the

four layers of the tcpip model beginning

with the fourth one and then the third

the second and the first

finally we're going to talk about

protocol binding and something called an

MTU black hole that doesn't really occur

much anymore but that Network plus wants

you to be familiar with

so as mentioned before the tcpap model

is perhaps the most widely known or used

networking model it's uh another

networking model that's most commonly

defined using abstract layers just like

we had with the OSI model and the entire

purpose of this model is to allow for

conceptualization of how a computer

network functions in maintaining

hardware and protocol interoperability

also it's commonly called the dod model

for the Department of Defense which

funded much of the research that went

into it uh TCP was permanently uh

activated in 1983 and it's been in use

just about ever since

that wasn't until 1985 this model was

actually commercially marketed but it is

now the preferred network standard for

protocols and so on

now this means that using these four

layers on this model the bottom being

the network interface layer the internet

layer the transport layer and then

finally the application layer and if you

know or remember the OSI model you'll

see that there is some resemblance uh

these understanding these this model and

understanding how data flows is actually

how the entire world is allowed to

communicate and connect to the network

so this is necessary for every computer

in the world that is currently using the

internet and for the most part that's on

any network we might find other smaller

lesser known protocols that do operate

outside of this but I think you would be

hard-pressed in today's day and age to

see that

so technicians and Engineers will

probably sit and talk about Technology's

implementation of these two models for

hours on end and the reason is because

there's quite a bit of history and

Brilliant thinking that went into the

creation of both of them the tcpap model

was in fact created before the OSI model

and it still makes it easier to

represent how communication and network

related Protocols are defined and relate

to one another however it's still more

common to hear technicians and

administrators use the OSI model when

they're troubleshooting or referencing

networking devices and there are many

similarities between the two models the

first similarity is the obvious use of

the layers to describe the functions of

these communication systems although in

tcpip we have four whereas in OSI as you

recall we have seven some of them even

have similar names as you can see uh

from application and transport and then

we see network or Internet and network

interface which is very much like

physical

in some ways some people consider the

TCP model to be a smaller version of The

OSI model however this leads to some

misconceptions about the position of

relationships of certain protocols

within the OSI model because these are

very two very different designs and they

have different purposes there are some

recognizable similarities but they're

still at their core different so the

purpose of this OSI model was an attempt

to simplify and standardize networking

tcp's original purpose as opposed to the

OSI is more attempting to sort of uh

sort out the internet protocols into

comprehensive groups according to their

functions of the scope and the sort of

network that's involved

now one of the similarities between the

two models is they both have

interchangeable Network and transport

layers

also each layer of the OSI model

directly correlates with the TCP model

and here you can see the application

layer the presentation layer and the

session layer of the OSI model

correspond to what we know as the

application layer of the TCP stack this

means that everything in the OSI model

that fell into application presentation

session are actually done in the

application support block

next the transport layer of the OSI

model corresponds directly to the

transport layer of the TCP model the

network layer of OSI with the internet

layer of tcpip and that is easy to

remember since internet is really short

for like internet working

and the data link and physical layers of

the OSI model correspond directly to the

network interface layer of the TCP now

some of these correlations it should be

mentioned aren't precise and exact

they're sort of

approximations and that's because they

are two very different models and

therefore they were created differently

and weren't necessarily created with the

one or the other in mind that being said

tcpip and OSI were built with knowledge

of one another and so we do see this

overlap now the TCP model outlines and

defines the methods data is going to

flow and commute in a communication

system it does this by assigning each

layer in the stack specific functions to

perform on the data and ultimately each

layer is completely independent of all

the other layers and more or less is

unaware of the other layers

for instance the topmost layer of the

application layer is going to perform

its operations if the processes on the

communicating systems are directly

connected to each other by some sort of

information pipe the operations that

allow for the next layer the transport

layer to transmit data between the host

computers is actually found in the

protocols of lower layers and from there

on each data layer will complete its

specified actions to the data and then

encapsulate the data where it's then

passed down the stack in the opposite

direction when data is traveling back up

the stack and we saw the same thing with

OSI model the data is then

de-encapsulated so when it's going down

we call that

being encapsulated

and when it's going back up we call it

D encapsulated so we really need to

understand how all of this works

together in order to get a really strong

picture of uh uh TCP and be able to

speak about the layers in general

so let's talk about encapsulation each

layer is responsible for only the

specific data defined at that layer as

we've said now these layers are going to

receive the data package from the layer

above it when sending and the layer

below it when receiving this makes sense

if I'm receiving data is going up so the

data is coming from below and if I'm

sending it's going down from the

application down to the networking

interface

now when it receives this package each

layer is going to add its own packaging

which is called a header this header is

used by the corresponding layer at the

receiving side for specific purposes the

exact purpose is really going to depend

on the layer in question but this header

is going to be added to the beginning of

the data so that it is the first thing

received by the receiving layer that way

each layer on the receiving end can then

remove that header perform its

operations and then pass the remaining

data up the stack up the TCP model on

the lowest layer a footer is also going

to be added

and this is going to add to the frame by

adding more supplemental information

this extra data

at the end of the data package is going

to assist the receiving end on ensuring

that the data was received completely

and undamaged this footer is also what's

called an FCS or a frame

check

sequence

and as the name implies it is going to

check to make sure the data was received

correctly now on the receiving end this

process is reversed by what's called

de-encapsulation in other words the data

is received at each layer and the

headers are removed to allow the data to

perform the related tasks where finally

the data is received by the application

uh the application layer and then the

resulting data is delivered to whatever

the requested application was now just

like with the OSI model we'll talk about

later this application layer doesn't

mean the actual application itself it's

simply the layer that provides access to

the information from an application now

just like the OSI model there are a few

mnemonic devices that can be used to

help in Remembering these layers in

order and the one that I use the most

going from the top down is called All

Things in networking again that's

application All Transport things

internet in network interface networking

so now we have a better understanding of

how the data is going to proceed from

layer to layer through encapsulation

going down from application to transport

to internet to network interface right

and then through D inter

de-encapsulation which goes the opposite

way let's take a closer look at these

layers starting with the topmost layer

the application layer so here on the

application layer much like the

application layer of the OSI model we

find what's considered the highest level

protocols higher level meaning these

protocols such as SMTP FTP and so on

these Protocols are not necessarily

concerned with the method by which the

data arrives at it says destination but

simply that it just arrives period

here in the application layer we also

provide the functions that relate to the

presentation and the session layers of

the OSI model as we've already pointed

out it does this typically through the

use of what are called libraries

which are collections of Behavioral

implementations that can be utilized and

called upon by services that are

unrelated

so this means that the application layer

of the TCP model

encodes the data and performs any

encryption and compression that's

necessary

as well as initiating and maintaining

the connection or the session as we can

see here these are just some of the

protocols that we find at the

application layer we can also further

group some of these applications based

on the specific type of function that

they provide for instance if we're

looking at protocols that are dedicated

to transferring files such as FTP or

tftp which of your call is the trivial

FTP then there are also protocols that

can be categorized by supporting

services so some of those are going to

be for instance DNS the domain name

service

and SNMP which is for management

purposes

or even boot P or the bootstrap protocol

now just like the OSI models application

layer this tcpip application layer is

responsible for process to process level

data communication this means that the

application itself doesn't necessarily

reside on this layer

what more means is that it defines what

the application or what type of

application can be utilized depending on

the protocol so for example SMTP

specifies that outgoing mail

communication with the mail or exchange

server and IMAP specifies the incoming

mail communication with the mail server

also remember that only those

applications that are network relatable

are going to be managed this layer not

necessarily all application so this

layer's role is more towards software

applications and protocols and their

interaction with the user it's not as

concerned with the formatting or

transmitting the data across the media

for that we have to move lower down into

the model and get to the transport layer

now on the transport layer of the tcpip

model we have two main protocols that we

need to be familiar with first we have

the transmission control protocol or TCP

and the second is the user datagram

protocol or UDP let me just write those

out here so that you can see what these

stand for again

now on this layer three things are going

on

uh data verification

error checking

and flow control

now our two heavy hitting Protocols are

done in very different ways so tcpap as

we've talked about in the past is what

we call connection

oriented which means there's a

guaranteed delivery whereas UDP is

connection last which means it's just a

best effort delivery

UDP doesn't have any means of error

checking that's one of tcp's areas of

expertise so to put TCP and UDP in

perspective I've always thought about it

as if say a grade school teacher needs

to send a note to a student's parent

because the student hadn't turned in

their homework for more than a week now

the teacher can send the note one of two

ways the first is through UDP or the

uninterested doubtful pre-teen now this

UDP is certainly going to make it home

as quickly as possible but whether the

message gets sent to the parent or not

it really isn't udp's biggest concern

getting there quickly is so UDP is going

to have you that quick

but not necessarily guaranteed now

meanwhile the other method TCP or

Teacher Calls parent this is the way the

teacher has a guaranteed delivery of the

message the parents aren't home the

message cannot be delivered or something

happens during the communication process

TCP will wait and attempt to send the

message again

so whereas TCP

UDP is quick TCP is guaranteed

and so that's sort of the give and take

there

now while our story is a generalization

it really touches on the two most

important characteristics of these

protocols now there are a few other uh

specifics about TCP that are are really

worth mentioning firstly and most

importantly we have reliability like we

just mentioned how it accomplishes this

is TCP assigns a sequence numbers to

each segment of data and the receiving

end looks for these sequence numbers and

sends what's called an ack or

acknowledgment message

which is something important that you do

want to

um

be familiar with and you might also see

that as a

sin act which is the synchronization and

that act message is sent when the data

is successfully received now the sending

transport layer doesn't receive the

accurate acknowledgment message then

it's going to re-transmit the Lost

segment secondly we have data flow

control which is we've already mentioned

this is important in as networking

devices are not always going to operate

at the same speeds and without flow

control slower devices might overrun by

might be overrun with data causing

Network downtime thirdly we have

something called segmentation and

segmentation occurs at this layer taking

the tedious task away from the

application layer of sectioning the data

into pieces or segments these segments

can then get sent to the next layer

below to be prepared for transmittal

across the media so the final

consideration for TCP is in order for an

application to be able to utilize this

protocol a connection between port

numbers has to be established the

devices try to create this session using

a combination of an IP address and a

port number now this combination is

called a socket

in the future modules we're going to

look at at referencing TCP and UDP as

well as going a bit more further into

explaining how they function and

interact with different protocols but

what you see here is the IP address

on a specific port number so we know

based on this port number what the

connection

is trying to attempt and whether or not

it's TCP or UDP we know whether it's

connection oriented or connection less

the internet layer of the tcpip model

corresponds directly to the network

layer of the OSI model now the data

terminology on this layer as I think we

discussed when we talked about the OSI

model is a datagram

now as the internet layer relates

directly to the network layer which if

you recall

was layer three we can a little more

easily understand a few things that

happen on this layer first it tells us

that this layer is responsible for

routing if you recall layer 3 devices

for OSI are routers

this means that it ensures the typically

fastest and best path from the source to

the destination

this layer is also responsible for data

addressing and if you recall with data

addressing we're dealing with the second

part of TCP IP which is the internet

protocol aptly name send is since it is

on the internet layer and the Internet

Protocol is responsible for a couple

main functions the first of those

functions is what we call fragmentation

it's important for us to understand

something called mtus which are maximum

transmission units

so that we know why fragmentation has to

occur now the MTU is the term as the

name implies that's used to define the

largest size of increment of data in

bytes that can pass through the given

Network device such as a router now

often data is going to need to pass

through networks with mtus that are less

than

the MTU listed on that device

generally even uh not just match two but

the lower it is the more it's preferred

because then we can make sure that it's

not going to have a problem so network

devices are going to send and receive

messages or responses to datagrams that

are larger than the device's MTU

in these instances when there is a

datagram that's larger than the MTU of a

device the transmitting internet layer

fragments the data or the datagram and

then tries to resend it

in smaller and more easily manageable

blocks

so once the data is fragmented enough to

pass through the remaining devices the

receiving ends internet layer then

pieces together those fragments during

the reassembly process now in the header

of those fragmented datagrams if we go

back just a bit you'll see right here

the header

there is a specific field that's set

aside for what we call three flag bits

the first flag bit is reserved and

should always be zero the second is the

don't fragment or the DF bit now either

this bit is off or zero which means

fragment this datagram or on meaning

don't fragment this datagram the third

flag bit is the more fragments bit

MF

and when this is on it means that there

are more fragments on the way

and finally when the MF flag is off it

means there are no more fragments to be

sent as you can see right here

and that there were never any fragments

to send so as we see here our initial

datagram that we wanted to transmit

had an MTU that was too large to send it

was

2500 and it was too large therefore to

go through router B and so then we

fragmented this datagram and added those

bits to the headers of the fragments

so that's how this all works and that's

why fragmenting is so important now

let's take a look at a networking

problem that used to plague Network

engineers and technicians that has to do

with mtus for some time this is also

something that's specifically called for

on the network plus exam now a black

hole router is the name given to a

situation where a datagram is sent with

an MTU that's greater than the MTU of

the receiving device as we can see here

now when the destination device is

unable to receive the IP datagram

it's supposed to send a specific icmp

response that notifies the transmitting

station that there's an MTU mismatch

this can be due to a variety of reasons

one of which could be as simple as a

firewall that's blocking the icmp

response and by the way when we talk

about icmp we're really talking about

the ping utility as well now in these

cases this is called a black hole

because of The Disappearance of

datagrams basically as you can see I'm

sending the data

the data gets here the device the router

here says wait a minute I can't fit that

2500 MTU through my 1500 sends a

response but for some reason the

response

hits this firewall and doesn't make it

back to the router and so the data is

lost into this black hole now this is

called a black hole because this

datagram disappears as if it were sucked

into a black hole now there are some

ways to detect or find this MTU black

hole and one of the best ways is to use

the Ping utility and specify a syntax

that sets the MTU of the icmp echo

request meaning you tell it I want to

Ping with this much of an MTU and so

then we can see if the Ping's not coming

back if it's coming back at one MTU and

not another then we know oh this is

what's happening right here and we can

determine uh where the black hole is

specifically occurring

now on the bottom of the tcpip stack is

the network interface layer now this

layer is completely dedicated to the

actual transfer of bits across the

network medium the network interface

layer of the tcpip model directly

correlates to the physical

and the data link layer

of the OSI model

now the data type we're going to be

talking about on this layer are what we

call frames as opposed to datagrams

and the major functions that are

performed on this layer on the data link

of the OSI model are also occurring at

this layer so we're really talking about

switching operations that occur on Layer

Two

which again is that data link layer

and so this is where we see switches

operating

which means that we're really dealing

with Mac addresses okay now a MAC

address again is a 48

bit hexadecimal universally unique

identifier that's broken up into several

parts

first part of it is what we call the oui

or the organizational

unique identifier

this basically says what company

is uh sending out this device

and then we have the second part which

is the Nic specific

and then we have the second part

which is specific to that device itself

so this is the manufacturer

and this is for the device you can

literally go online search for this part

of the MAC address and it'll tell you

what company is creating this device

now the easiest way to find the MAC

address in a Windows PC is by opening up

the command prompt and using ipconfig

all which we've talked about in a plus

this brings up the Internet Protocol

information the IP address and it also

brings up the MAC address or the

physical address that's assigned to your

Nick

so now that we've covered the MAC

address is it's really important to

understand the parts of an Ethernet

frame and remember we're talking about

frames at this juncture

so the Preamble of an Ethernet frame is

made up of seven bytes or 56 bits and

this serves as synchronization

and gives the receiving station a heads

up to standby and look out for a signal

that's coming

the next part is what we call the start

of frame delimiter the only purpose of

this is to indicate the start of data

the next two parts are the source and

destination Mac addresses so the

ethernet frame again this is everything

that's going over this ethernet uh over

the network we have the Preamble it says

Hey pay attention now this that says now

I'm giving you some data and then we

have the destination and the source Mac

addresses so that way we know where it's

coming from who it's going to and this

takes up 96 bits

or 12 bytes

because remember this is 48 bits right

here so if we double that that's going

to be 96 and then the next type is

What's called the frame type this is two

uh bytes that contain either the client

protocol information or the number of

bytes that are found in the data field

which happen to be the next part of the

frame

which is the data this field is going to

be a certain number of bytes and the

amount of data is going to change with

any given transmission the maximum

amount of data allowed in this field is

1500 bytes we can't have more than that

now if this field is any less than 46

bytes then we have to actually have

something called a pad which is actually

just going to be used to fill in the

rest of the data

and the final part of this ethernet

frame is called the FCS or the frame

check sequence and this is used for

cyclic redundancy check which is also

called CRC this basically allows us to

make sure that there are no errors in

the data now similar to the way that a

an algorithm is going to be used to

ensure Integrity of data the CRC uses a

mathematical algorithm which sometimes

we're going to refer to as hashing which

we'll talk a lot more about when we get

to Security Plus

that's made before the data is sent and

then it is checked when it gets there

that way we can compare the two results

bit for bit and if the two numbers don't

match then we know the frame needs to be

discarded we assume there's been a

transmission error or that there was a

data Collision of some sort and then we

ask the data to be resent

now this layer by the way this network

interface layer is also responsible for

the network access control and some of

the protocols that operate on this are

what are called uh point to point

protocols ISDN which is a which we've

talked about also a type of

um

Network and also DSL so these are some

of the things that exist at this and

this makes sense because again we're

dealing with the physical bits bytes of

data

so now that we've taken a look at each

of the layers in the TCP model there's

still a couple things that we still need

to Define now we've discussed how some

of the protocols that we've seen relate

to the OSI model as well as the tcpip

model and we found that some of the

protocols function much more smoothly

when they're put into the context of an

outline of one of these models so the

next definition I want to make sure to

cover is something called protocol

binding this is when a network interface

card receives an assigned protocol it's

considered binding that protocol to that

Nick so just we learned how the data is

going to be passed down from one layer

to the next it's very important that we

have these protocols bound to the Nick

we can have multiple protocols actually

bound to one network interface card now

of course the most easily recognized we

can most easily recognize these when

we're looking at the ipv4 and IPv6

configurations in our network connection

Properties or adapter settings in

Windows so for instance you use a

specific protocol more than others and

you're confident in the stability of the

connection you can change the order of

binding

to potentially speed up your network

since what it basically does is it's

going to give a list

of each protocol that exists and it's

going to hit each protocol one after the

other so if there's one that you use

more you can set that at the top so it

doesn't have as far to go so as we can

see here we have several default

protocols

and they're going to be tested in order

for that available connection

and the first protocol that's found to

have a matching active protocol on the

receiving end is going to be the one we

use now that while this might sound like

a pretty decent method of doing things

it also opens your computer up to

utilizing a lesser protocol which is

potentially going to give you a slower

speed

so the graphical interface or properties

menu for your um network interface card

is where you're going to be able to

configure all of this stuff stuff such

as tcpip

DNS server assignment DHCP and so on and

so forth so after all of this it's

really important to understand that all

this organizing categorizing defining of

these protocols the assigning of rules

and roles all of this the the internet

didn't just happen overnight it's not

even necessarily the way we did it on

purpose these standards and these models

are going to continue to expand and

change and eventually might even have a

brand new model that we're going to have

to learn about

but in the meantime these models are

here to stay and they're going to remain

really important and especially uh in

the future you have to understand the

historical roots of the network so you

can be able to Define not only how to go

forward in the future but also how to

you know prepare yourself for a network

plus exam so let's just go back over

everything we've talked about one last

time we covered in great a lot of stuff

here right first we explain the purpose

of the TCP model and we compared the

tcpip model with the OSI model

remembering that the top three layers if

we look at this

if we do the three two one and then we

look at seven six five four

right two and one physical and data link

are going to go straight over here

to uh that physical layer one of the

tcpip model

then

the network layer is going to

correspond directly to the internet

layer the transport layers are going to

be the same

and

session presentation and application all

go over to the presentation layer in TCP

we also talked about defining data

encapsulation and we walk through how

fragmentation works on the internet

layer

and the reason we need to do that is

because of the maximum transmission unit

finally we talked about the fourth third

second and first layers of the tcpip

model and on each model we outlined some

of the important aspects of each layer

such as the

um

application layer

which again is the way that the

application is going to process all this

information the Tran sport layer

which is in charge of reliability

and it is where TCP which is connection

oriented or UDP which is connection less

live and this is also going to deal with

flow control

and also segmentation

we looked at uh Layer Two as well which

is the internet layer

and the fragmentation that happens there

and network one the network interface

layer

which is equivalent to all that physical

stuff that we've talked about we also

looked at how the terminology changes

remember on layer four we're talking

about data

on layer three

we're dealing with segments

on Layer Two

we're dealing with datagrams also called

packets and we broke down then on layer

one

frames and an Ethernet frame and all the

information that goes into that

finally we Define what an MTU black hole

was and we finished off everything by

talking about protocol binding which is

binding certain protocols to specific

Nicks and in a in a delineated order

[Music]

Network infrastructure and design

ethernet and implementing a wireless

network

so in the previous modules we were

introduced to many networking standards

models and Technologies now this module

is going into ethernet a little bit

further and specifically the

implementation of a wireless network so

the module objectives are first to

outline the different types of ethernet

networks that exist and then we're going

to go into the explanation of WLAN or

wireless LAN architecture

then we're going to Define and describe

the characteristics of an antenna and

have different types of antennas which

is actually pretty important for the

network plus exam specifically

wireless antenna performance factors and

then by the end of the module we're

going to have a complete understanding

of the 802.11 standard and its

Associated modes we're going to talk

about uh the beacon frame and we're also

going to talk about what determines

where you place your wireless access

point or your WAP

and we'll finish by talking about how to

properly Implement a wireless network

so an Ethernet network is perhaps one of

the easiest networks to plan and

implement depending on the size of your

network and the equipment being used

there are a bunch of different kinds of

small ethernet Network implementations

that you can use some of the typical

equipment that you're going to find in

an Ethernet Network might be a hub

an ethernet cable which can either be

what we call straight through

or crossover

and we've looked at that a little bit

more in depth previously

and a switch

or and a router so a network can also

contain a combination of these or all of

them generally so much we're not going

to see hubs a lot anymore but they're

still mentioned on the exam

so a very simple ethernet Network that

involves a hub is called a Hub Network

Now to create this network all you need

is two devices

a hub

and an ethernet cable

this type of network is not capable of

reaching the internet and it's typically

only going to be used for file sharing

or printing and you're not going to want

to have a lot of devices either because

it's quickly going to become very slow

due to the fact that hubs as you

remember operate on layer one of the OSI

model and therefore broadcast every

um uh input data out to everything else

now the next type is also very easy to

implement this is considered a crossover

Network or a peer

to peer Network and the reason is

because there is no device sitting in

the center

a crossover Network only needs the two

devices in the crossover cable to

connect them and the reason we must use

a crossover cable is because we're

switching if you recall the one two

three six pins we're switching these

pins so that way on one side the data is

sent on the other side it's received

of course newer devices might not always

need this crossover cable anymore

because a lot of modern Nicks have Auto

switching capabilities which will

automatically determine and switch these

pins for you now another ethernet

network is one that uses a router to

connect devices to the outside world or

to the internet

and a switch can often be placed in

between the router which leads out to

the Wan

in the internal Network or the LAN in

order to alleviate Network congestion

and to allow for more devices to be

added

now just so we remember a switch

operates on Layer Two although there are

switches that do routing and those are

called layer 3 switches and then the

router as we just mentioned operates on

layer three of the OSI model

now another point about ethernet

networks that is important is that

ethernet uses destination and Source

access points to assist in keeping tabs

on all the multiple channels that are

used in network communications these are

called sap or service access points and

in the previous modules we discussed how

data flows through these layers in the

network models well here these access

points are used to map the network layer

communication or IP through the physical

layer or layer 1. now the access points

allow a single physical connection to be

utilized for many logical connections

for tcpip this would be like a Nick

because these access points are going to

be on the local side only they're

selected by the server managing those

services

now to keep what TCP as an example when

a user is accessing a website for

example

a connection is made with the web server

and the computer downloads that website

along with the website are references to

parts of the page such as files that are

associated with the web page sound image

other things like JavaScript and these

files are stored on the web server and

when the user interacts with the website

the access point ensures that the

computer can differentiate between the

ethernet frames for the images and those

for sound files and those for other

types

okay so in a lot of the previous lessons

we've been talking about the methods of

connecting our devices mostly through

physical means and we defined that many

Technologies are commonly used in both

wired and wireless networks otherwise

known as bounded and unbounded networks

so here we're going to discuss

specifically WLAN or Wireless local area

networks in Greater detail starting with

the architecture

there are several components that we

really need to Define

the first component is what's called an

sta or the station

the wireless sta is any device that has

a network adapter card or Nick that

conforms to the 802.11 standard

and you remember the specific standard

for wireless is 802.11 as opposed to

8023 which is ethernet now the next

device is called an AP or an access

point look familiar now this is very

different from the service access point

I just talked about because an AP in

this sense it is a device or a software

implementation that allows wireless

devices to communicate with each other

and to connect to a wired Network an

access pointer AP also sometimes called

wireless access point offers wireless

devices some higher levels of security

as well and can act as the bridging

component

between the STA

and the backbone of the network for

access

so the next component that we need to

identify is the WDS or the wireless

distribution system this device is the

authority in terms of Access Control to

resources and ensures that devices are

mobile this allows multiple access

points

to be interconnected wirelessly which

allows you which allows the aps to be

connected and extend the wireless range

of the network without having to connect

the wire at the access points directly

to the backbone and again the backbone

would be the internet

or the rest of the network if we're

talking about a lan now the system has

three types of AP stations we have

something called a remote base station

which is the access point that connects

directly to the wireless clients or

devices a relay based station just

relays or repeats the information

between other stations or devices and a

main base station

now the last thing I want to talk about

is the main base station which is

connected to the wired or Ethernet or

backbone Network

using these components there are a

number of different ways we can actually

configure a wireless LAN the service set

is what defines how your network is

configured now there are three standard

ways that W lands or Wireless Lans can

be configured

first configuration is what's called a

BSS or a basic service set the BSS in

its simplest sense is comprised of an AP

an access point and an sta a station

although many stations with a single AP

is also considered a BSS so I only need

one station but I can have multiple the

trick here is that I have only one AP

now client nodes like these may not be

necessarily explicitly aware of each

other using a BSS we are easily

able to extend our network coverage area

and the distance between our wireless

devices by forwarding

packets

through a wireless access point

so that we can gain access to the wired

Network

now wlans can also be configured in

what's called an ESS or an extended

service set an ESS is comprised of two

or more bss's basic service sets and the

purpose of an ESS is to allow mobile

devices to maintain a constant

connection

it's the network while you're roaming so

each BSS in an ESS or an extended

service set is going to have the same

service set identifier otherwise known

as an SSID

this makes multiple bsses appear as if

they're only one

so as an example if you think about when

you walk through an airport pretty much

wherever you sit we have a decently

strong Wireless signal theoretically of

course so thinking about what's that

signal they wouldn't be easy for a

single access point to provide you a

signal that's that strong for that much

space in fact it's pretty much

impossible so instead there are many

access points APS arrange strategically

to allow full coverage throughout the

airport and combined they make up this

ESS or extended service set that's why

we see the same network name no matter

where you are within that Network range

now the BSS can either operate on the

same channel or on separate channels

which effectively increases the

throughput by having separate channels

that they're not going to overlap on

finally we have What's called the ibss

this is an independent basic service set

and ibss is created when there is a

isn't a controlling access point but

instead there's what we call an ad hoc

network and as the name implies

this means that uh this is a makeshift

or an improvised in technical terms uh

wireless network that combines Network

elements to make a network with minimal

planning where all the devices on the

network are essentially equal in status

and are free to talk with any other ad

hoc devices that are in range this ad

hoc configuration which is also called

by the way a peer-to-peer configuration

is where stas are performing their own

AP functions as well as their own client

operations independent of any sort of

central device

so if you've ever connected two

computers directly together in order to

say

transfer files or perhaps you've

connected your smartphone directly to

your computer in order to transfer files

without the use of an access point

you're using what's called an ibss or an

ad hoc wireless network many aspects of

antennas and their characteristics that

are a little outside of the scope the

network plus exam but there are still a

few Basics that are important

the first of which is to Define what an

antenna actually is and how it functions

on a fundamental level

so an antenna is a physical device that

are transmits or receives

electromagnetic waves and then converts

those waves to and from high frequency

signal now the antenna's physical

characteristics and dimensions are going

to dictate these frequencies that it can

transmit or receive and depending on the

purpose of the antenna

there are different types that can be

used for instance the radiation pattern

is different on some antennas versus

others

now another term we really need to

understand is the term gain which

describes the intensity of an antenna in

a specific Direction related to the

hypothetical intensity of a given

standard which is the ideal in other

words we always have a hypothetical

versus

the reality

now this is achieved by focusing on

What's called the RF or the radio

frequency

in a more manageable or concentrated

plane this is what we see as strength on

your computer right if you've seen this

thing and you have different

number of bars that's what we're really

talking about here is the gain

in most cases we want more gain which is

better but there are certain legal

limits and adding power can potentially

have some negative ramifications so gain

can also come from an external Source

like an amplifier which means that it

amplifies the signal making it stronger

and it's measured in decibels

now while this explanation is very

simplified the antenna gain is how it's

affected by things such as the size and

shape of the antenna and the amount of

electrical power that's applied to the

signal and it's all kind of complicated

which is why there are people who

specifically are RF or radio frequency

engineers

so what you really need to remember

about all this is first

the physical characteristics of an

antenna affect its gain

second a higher gain is usually good but

potentially dangerous

third more gain can be achieved by using

an amplifier and fourth we're going to

measure it in decibels

so now that we've defined some of this

terminology when it comes to antennas

let's take a look at some of the

wireless antenna types

now Wireless antennas can be fairly

organized into two general broad

categories the first category is

directional directional antennas attempt

to focus the radio waves into a narrow

beam going in one specific Direction

because the signal is being focused it

typically means that these antennas are

going to have a higher gain

and for the same reason a relatively

narrower transmission beam versus other

types as you can see

these characteristics allow for a couple

of Bennetts benefits such as a focus

beam which ensures a better signal

quality and a smaller transmission beam

which means that there's less area of

interference

how directional antennas are really

commonplace in implementations of

point-to-point networks which makes

sense because I have this Limited sort

of area in which the waves are going to

be traveling and perhaps most commonly

you've seen them in Dish Networks for

satellite TV and the internet

now the next category of antenna is are

called omnidirectional antennas this

type of antenna emits the radio waves in

all directions on the same plane equally

in some ways these are called donuts

because

the wave comes out in a donut looking

shape now because the signal is being

transmitted in any direction such as on

a wireless router

these antennas have a relatively low

gain when compared

with a uh directional antenna now where

these antennas lack and gain they make

up for it because obviously they have a

greater coverage area

as the donut wave implies

the good part about this greater

coverage area is that transmitting and

receiving Stations don't have to have a

specific alignment with one another

they can be in any direction from the

antenna these antennas are really going

to be used in distributed networks and

multi-point networks as well so

omnidirectional antennas are implemented

everywhere from cell phones to radio

broadcasting antennas to walkie-talkies

to GPS to mostly our wireless networks

at home and in a lot of offices Etc

so now that we've talked about a lot of

the different types of antennas and

their characteristics the the last thing

I'd like to mention about gain is the

more gain the antenna has the smaller

the effective angle of use needs to be

so the next thing we need to do is

outline what's going to affect the

performance of these antennas

so the physical layer of the network the

transmission of bits from one point to

the other there are a lot of things that

can hinder the data while it's in

transit these things that are going to

impede our signal are going to depend on

the type of data in transmission

so for infrared data Transmissions the

antennas need a line of sight or Los

just like your remote control almost

anything that obstructs this loss is

going to affect the signal this could

include stuff like smoke smog fog dust

even pulses of light and bright sunlight

can very easily change the maximum

transmitting distance and obviously if

anything

standing in the way we're going to be in

big trouble

now for microwave Transmissions the

signals also considered Los or line of

sight this typically doesn't mean that

we need to be able to see the receiving

station with our naked eye it just means

that the signal has to have an unimpeded

path from the source of the destination

most commonly satellite the ground

station has to be within the footprint

of the orbiting satellite generally

speaking

distance is the performance Factor

that's going to affect these microwave

Transmissions the most

now the factors that are going to affect

radio Transmissions which are the ones

we use in Wi-Fi settings mostly start

with the antenna itself

so the signal characteristics of an

antenna can affect the maximum

transmitting distance also performance

can be limited if there are any objects

that are very electrical or give off a

lot of magnet magnetic fields near or

around the transmitting or receiving

stations and this is going to cause

problems to arise

we can also have normal ambient noise or

environmental conditions which can

affect the distance these signals can

travel finally the greatest factor

that's going to affect Bluetooth

Transmissions is the distance between

the uh the devices just because of the

technology we're using as most Bluetooth

devices are what we call Class 2 devices

this means that we have about a 10 meter

which is equivalent to around although a

little more than 30 feet

and this is due to power limitations now

depending on the type of Bluetooth

device it may operate on the 2.4

gigahertz

frequency which by the way is the same

as Wi-Fi and so there that's why we're

going to have a problem and sometimes

we're also going to see it on the 4.6

gigahertz frequency

and for those that operate at 2.4

obviously not only does radio operate at

those or Wi-Fi connections but also

phones and so on so there's a lot of

potential for

having devices on the same frequency

that are going to impede its

communication

now one other term I want to talk about

is a term called latency this is we've

mentioned it a couple times in previous

modules but I haven't really defined it

latency is basically the time delay in a

given system depending on what system

you're measuring it might mean slightly

different things so the system we're

most concerned with is the network

latency which can be measured in either

one way or round trip latency and I'm

sure that you can understand the

difference there

the latency is the amount of time it

takes for data to go from a source to

destination and we're just dealing with

bat round trip

it coming back as well so the round trip

adds the two one-way totals

and doesn't include the processing time

of the packet so only because it's sent

and then takes a certain amount of time

to come back doesn't mean that is all

latency because some of that is how much

time the computer is spending processing

that information

obviously we want lower latency

and to measure it we can generally use

the Ping utility which is going to tell

us in milliseconds how long a packet

took to go there and come back

now let's look at some of the 802 11

standards and see which specifications

have the least amount of latency so

these 802 11 standards cover the proper

implementation setup and performance

minimums and device specifications for

wireless local area networks these all

fall under the 802.11 specifications

they also specify the method for which

those wireless networks as carrier sense

multiple access with collision avoidance

or csma CA which we've talked about

are going to operate

and it also designates the 2.4 gigahertz

frequency

as the band for the sped Spectrum

devices that are going to utilize for

reliability now over the years there

have been several standards in this

family that have been ratified the

original was 802.11 just plain old it

was named for its release in 1997 so the

1997 is part of that and it was

specified to operate the 2.4 gigahertz

frequency band and was rated for data

bits at about 2 megabits per second

which as you imagine would not be very

useful for us now and therefore it is

very obsolete at this point

the 802 a standard which was released

two years later was designed to operate

at the 5 gigahertz band and it had a 54

megabit data rate now while it would

seem that this standard would sort of

lead the charge in Wireless standards at

the same time that 802a was released

there was also 802 B which was released

and 802b operates at the 2.4 gigahertz

band and essentially was a direct

extension of the original

802.11 1997 standard now even though the

data rate was faster with 802.11a there

were some initial downsides to that

standard that kept it from being the

most popular

first this higher frequency uh had a

lesser range and so you could travel

travel less distance

also when 802.11b came out it was a lot

cheaper

than 802.11a and that made up quickly uh

with consumers and so it quickly became

the de facto standard now it's popularly

grew rapidly and though it operated at

2.4 gigahertz and therefore was open to

uh you know was really susceptible

to a lot of interference uh it still was

the one that almost everyone used uh and

so that's sort of where it went because

range

was such a big deal the next standard

which was released in 2003 was the 802

11g standard and this specification used

the 2.4 gigahertz frequency again

but the data rates took a major leap up

to 54 megabits per second just like

802.11a now since it used the 2.4 band

it made backwards compatible with

802.11b so it was very easy to integrate

and it therefore became the preferred

standard now after 80211g took over the

market it wasn't until 2009 that we

finally got the 802.11 N standard and it

was released with something called a

memo

which was a type of antenna

or multiple

input

multiple output

and it had multiple antennas and that

greatly improved the network performance

also this amendment was specified for

both 2.4 gigahertz and 5 gigahertz bands

and so these improvements made the

standard really popular especially

because it was backwards compatible not

only with G but also with b and even a

and it was rated for a maximum of up to

150 megabits per second now the range of

these Wireless standards is also

specified the original 802 11 1997 and a

have a range of about

20 meters B and G

have a hundred meters

and N is approximately 70 meters so we

lost a little bit of distance because we

added that five gigahertz band in but

for most people this didn't really

matter since we could use again an

extended service set and simply add

several 80211 devices

now while you might have heard of some

newer standards available and even some

that are just coming around the corner

these four are the ones you really need

to know for the exam and so those are

the ones I really want to concentrate on

so if we look at these in a little more

organized Manner and we can recap the

important parts the 802.11 standard 1997

worked on a 9 a 2.4 frequency had a

range of 20 meters

and had a two megabit per second data

rate

Ada 211A was at 5 gigahertz 20 meters in

range 54 megabits it's compatible with

802.11n 8211b operated at 2.4 gigahertz

had a 100 meter range 11 megabits per

second and is compatible with G and n

ative to 11g also 2.4 gigahertz 100

meters and it was 54 megabits per second

so it's increasing the top the speed

and was compatible with the previous and

the next one which is 802.11n which not

only operates at 2.4 gigahertz but also

five

has a slightly less range but it does

have a higher megabit per second data

rate some would even claim that this

goes up to 600 depending on your

theoretical and it's compatible with all

of the previous versions

now there are two modes that are

supported by the Ada 211 standard the

first is what we call infrastructure

mode this is the mode that's configured

to use wireless access points to connect

workstations to a cable backbone

the network using the infrastructure

mode is going to either use a basic

service set or an extended service set

the other one we have which we already

mentioned is called ad hoc mode this is

for those peer-to-peer configurations

and again it's referred to as an

independent basic service set or an ibss

now the configuration of this mode is

designed with each Wireless workstation

able to communicate directly with one

another without having to go through a

central device

now earlier in this module we talked

about the service sets of many kinds and

we talked about frames in previous

modules now keeping those in mind it's

important to understand how these

devices such as laptops and smartphones

know what wireless networks are

available when we access them

now this comes by detecting and

receiving what are called Beacon frames

a beacon frame is a management frame

that's 50 bytes long and it contains

information about the transmission

process such as the SSID or the service

set identifier

which is essentially the name of your

network

the SSID is that text string that

identifies the network it's 32 bytes

long might be for instance Bill's

Network or something like that now the

beacon frame is used to start and

maintain

the wireless communication session and

it's sent in regular intervals from the

axis point and those intervals can be

manually changed or set by an

administrator and we can even turn them

off so that way or hide them so that's

not being broadcast

now when it comes to installing a proper

wireless network implementation we need

to be familiar with the typical process

and the steps to maintain the highest

level of functionality now much like a

lot of different processes the basic

steps to take are pretty much the same

they begin with planning so there are a

few things that are helpful to collect

before the planning process

we need to collect information about the

floor plan of the building where we want

to install and so we can design a

topology and figure out where to put

access points we need to establish

requirements for how many devices are

going to connect which 802.11 standard

we're going to use what type of security

is going to be required and so on now

all of these are crucial to proper

planning without this information it's

just going to be easy to choose the

wrong devices or the wrong Technologies

also if the research isn't done

beforehand you're going to find yourself

performing a lot of rework at the end

now once this information is designed

and gathered

we can start to establish the type of

access points and the number of APs

needed knowing the number of users on

the network is going to help us

determine for instance how many access

points and we want to balance the number

of users with the access points in order

to make sure that we have a good load

balance

the next step is to assess the building

to see if anything around might cause

interference

specifically it's important to install

anything that's going to be on the 2.4

gigahertz band now remember some of the

things that can cause interference are

Bluetooth devices other wireless

networks heavy duty machinery and so on

we also need to determine the exact

placement of the access points are they

going to be placed in the ceiling or

somewhere visible or somewhere like a

secure room and when we determine this

we need to make sure that there's we're

looking for obstacles that are going to

impede like thick walls doors metal

shelving uh proximity to large

electrical equipment and if those

obstacles Can't Be Moved we might want

to choose a different location for our

access point

so now that we've planned the next part

is the fun part the actual installation

here we need to configure the device to

connect it to the network and some of

the standard things we're going to do

are connect the router

change the administrator default

settings that the device came with and

configure DHCP services and encryption

levels such as whether we're going to

use WPA

or WEP and also are we going to use one

of the three channels are we going to

have them auto check or what another

thing we might want to do is create

what's called an access control list

which means we can allow only specific

computers to get access to our

network via Mac addresses which are

again the physical addresses on a

computer

or on a network card

next we need to configure the client

workstations and we need to test your

functionality now it's important here

because not all operating systems can

use all the different standards they

might even require a software update of

some sort

you might want to make sure to test the

wireless device by walking around a

building and make sure you can stay

connected and that you can connect in

the first place anywhere you need to and

then you also need to take the device

outside and make sure that no one can

get in from the outside so it's actually

quite difficult to just start one of

these from scratch the last step in the

process is to document every single step

that was made and it's always a good

idea to Baseline for future testing and

implementations now being able to

successfully accomplish the two phases

the planning phase and the installation

phase needs to be a part of your skill

set needs to be something you understand

for the network plus exam so just to

recap everything we've talked about the

first thing we did is we outlined the

different types of ethernet networks

whether that means it's a Hub Network

a router Network

or a peer-to-peer Network

we also explained WLAN architecture

looking at the difference between a

basic service set an extended service

set and an independent basic service set

we defined and describe the

characteristics of antennas looking at

gain

and the types of impedances that could

occur

then we outline the Ada to 11 standard

including a b g and N which are the

different modes

we also talked about which frequencies

these live on whether 2.4 or 5

and how fast are the megabits per second

that each one provides you want to make

sure to commit to memory that table that

we displayed on an earlier frame

we also talked about defining Beacon

frames which broadcast the SSID and tell

computers how to connect to the wireless

network

finally we outlined what factors are

going to result in where you place your

access point and how to properly

Implement a wireless network point

from the planning

and implementation stages

[Music]

welcome to module 5 lesson five

IEEE 802.11 AC actually we're going to

look at a little bit more than that the

N standard 82.11n

AC Channel bonding

now the 802.11 it's a specification for

wireless LAN WLAN communication it uses

mimo which we shorten from a multiple

input multiple outputs I'm sure you can

see why

so in this technology the transmitter

and receiver use multiple antennas

I've put a little diagram on the bottom

here from um ieb media

that it will demonstrate at the bottom

certainly you can see three channels in

use simultaneously multiple channels on

the top part of the Fig you can see you

can select from but it's only using one

so in this standard the end standard

multiple antennas provide independent

paths in space between the transmitter

and the receiver

to send or receive streams of

information at the same time on the same

band

what my mode does is increase the number

of data streams sent from an access

point to a client which you can see in

the bottom part

in 802.11 mimo four spatial streams can

be sent to a single client at a time

again if you want to read further you

can now look up the specifications

there's a few Wireless specialty books

if it's something you're interested in

doing it's certainly an interesting

field

uh the 802.11 AC is an enhancement of um

11n

obviously still Wireless networking it's

designed for high throughput our

wireless Lans on the five gigahertz band

there's a few advantages to using that

it uses a multi-user form of Mimo

in their mind mode the access points has

multiple streams of data at the same

time to different clients over the same

frequency spectrum

in uh 802.11 acmu mimo eight special

streams can be divided among up to four

clients I think the MU is multiple user

yeah multi-user mimo at the bottom and

you can see the stream can be broken up

you've got a few options you can have a

higher stream to one client and then

lower bandwidth stream to another

clients

supports treatment of HD videos which is

really handy and to multiple clients

because of low latency high throughput

and reliability

it operates in the five gigahertz band I

already mentioned that theoretical data

rate of 600 this has been improved on

all the time so maybe check up on the um

standard before exam day

you've got less interference than in the

2.4 gigahertz band which is where you

get the increased performance more

channels available for data transmission

greater number of non-overlapping

channels than you do in 2.4 megahertz I

think there's a couple of disadvantages

as well but I'm not sure I'll put them

down here in the slide

so the U.S a five gigahertz band has 25

non-overlapping channels whereas 2.4

gigahertz is only three

uh Channel bandwidth of the following 80

160 20 it's worth and making a note of

all of these in case it's asked in the

exam and 40.

uh obviously needs to comply with the

standard you can see this particular

adapter's got it written on it it's got

a AC standard written on it

to comply with the standard as to

support the 2040 80 megahertz Channel

bandwidth in the 5 gigahertz band

the 160 megahertz Channel bandwidth is

optional

80 megahertz channels are formed by

combining combining the following

following two adjacent none overlapping

40 megahertz

160 megahertz are uh combined to 80

megahertz I think you can see how this

works

so here I've put

um

a slide from Wi-Fi Jetty website they've

combined two channels here to 20

megahertz channels are made of 40 for

channel bonding

so Channel bonding was first introduced

with 802.11n

in Channel bonding two or more channels

adjacent to each other are combined to

increase bandwidth as you can see in the

figure put there

benefits 802.11 AC benefits because it

supports the following channels 2040

80 megahertz

uh although 160 megahertz channels are

supported as an option is its

availability depends on your geography

Where You Are

well I just had a bandwidth increases

the data rates so

um 11ac uses eight spatial streams and

160 megahertz bandwidth

to achieve a maximum data rate of 6.933

gig

uh data rates vary on the following for

11ac you're given bandwidth and the

number of spatial streams used

probably worth um writing out this

um

table here if you want the information

or you can do a screen capture

802.11 AC with one spatial stream and

for a bandwidth of 20 megahertz can

ensure either data rate of

86.7 megahertz and so on and so forth

for the others um their data rate

increases both vertically and

horizontally

all right so we've covered NAC Channel

bonding that's all for now thanks for

listening

[Music]

plug the module 5 lesson 6 in network

segmentation

quite a bit to cover and some of this is

a little bit esoteric to be honest so um

it's conceptual

it can be a bit hard to get your head

around

um in that sense

what is Network segmentation what is

physical segmentation logical

uh the uses why bother

and critical situations so we're hitting

a few the syllabus topics here in the um

Network plus syllabus so

in a sense Network segmentation concerns

dividing a computer into Network or sub

networks not in the sense of

um subnetting

um in the context of Ip addressing but

um dividing our network down

so each portion of the network is called

a network segment

it can be characterized by a physical

boundary

or logical So Physical something you can

see logical something that the network

can see but you couldn't see physically

you would then have to log in and check

the configurations

so physical or logical boundary

separates various Network segments from

one another

physical is a bit easier the computer is

divided into segments for example with

switches

routers a group of physical access and

assets is part of a specific Network

segment

so a bit harder to do with switches

because you would normally needed to add

a configuration because switches are

designed to broadcast to other

um parts of the network if it doesn't

know where that part of the network is

or particularly device

whereas routers do the opposite

computer network is logically

um

virtually divided into Network segment

so this is uh from The Logical

standpoint so we could do it with

virtual lands or vlans

virtual segmentation is done or

different connections or the same

physical switch so you can have 10

switch ports and the first five ports

are in one logical part of the network

in one VLAN VLAN 10 for example and the

other five in VLAN 20. and you could

have multiple vlans depending on your

capabilities or whatever switch you're

using

through through Network segments are

isolated although secure communication

can be established between them to share

network resources we cover that with

security and elsewhere you can actually

have an internal and external network

security it isn't just for example vpns

connecting and through from remote

offices

so why would you bother in a sense it

enhances the security of the network you

can isolate critical parts of your

infrastructure from an authorized access

for example if you've got a special

service and server you can restrict

access to the um users don't access it

and they don't have direct access so

they'll be in a different VLAN for

example or just in it wouldn't appear on

the network and you normally or may well

have depending on the size of your

network a different team or Department

managing that part of the network

it can be used for reducing Network

congestion so you're dedicating certain

parts of bandwidth for certain segments

of the network and you can even have a

high-speed department for example

um the company I used to work at we had

a design team who all used

um high speed high resolution files and

graphics and it um they needed

um a fast connection so they had their

own logical segment

and you could also limit traffic as I

said faster connection for some slower

for others and the available bandwidth

is um increased or reduced accordingly

uh also useful for load balancing you

can distribute the traffic a load based

on the

for the network certain devices certain

devices can be placed in certain

segments

and network segmentation is also done

for the PCI the payment card industry

that's different from the PCI bus

technology which we discuss elsewhere

the PCA compliance standards were

created by Major card issuers and you

may come across it if you have to take

online payments

um depending on the processor you use

even if you've got a small

um Network for your business or shop you

um may have to or you will be affected

by PCR compliance

so this is to ensure that the payment

transactions are done in a secure

environment

if someone processes stores or transmits

credit card information it must comply

with the PCI Data security standard

which is the DSs

this is mandated by Visa Mastercard

American Express discovering JCB

obviously because people will try and

capture

and credit card information so it needs

to comply with the standards

um Network segmentation is actually not

a PCI DSS requirement it's done to

isolate the traffic that stores

processes or channels emits the card

holder information from the rest of the

network

and reduces the scope of the network

environment subject to PCI compliance if

you didn't have your network segmented

then your entire network would have to

comply with all of the various pcid SS

requirements if you segment the card

processing and part of your network then

only that part of the network needs to

comply so it's going to make your life a

lot easier

um uses the footprints of a sensitive

information is confined and this is what

I I mentioned a moment ago and you can

protect it using firewall or your

intrusion detection or Protection

Systems

and reduces the audit cost as well

the audit is done for specific Network

segment as opposed to your entire

network and again the best example is

when you're getting audited for the

purposes of of PCI compliance

and this is one of the uh topics for

these syllabus actually Network segment

segmentations

in critical situations numerous

situations where the network

segmentation is critical

so the scada the supervisory control and

data acquisition and the ICS industrial

Control Systems so again you'll see

you'll see this on the syllabus when you

look the ICS refers to several control

systems that are used in the industry in

various Industries this is an industrial

control system so you may not have heard

of this or may never come to deal or

support or manage this unless you're

part of the industrial Network

infrastructure

thank you

and the additional facilities are

electrical electrical power grids water

distribution oil natural gas pipeline

systems

and they're dependent on electrical

hydraulic and mechanical equipment

this equipment is all monitored by

sensors that transform the physical

stimulus for example something's broken

or stuck

or doing too much or too little of what

it should be doing and this is

um changed into electrical signal

and in a basic SC Ada system when

industrial operations are performed the

information from the sensors is sent to

a a controller or a number of

controllers the controller is a type of

computer that receives the information

from the sensor

now what happens with this information

just depends on the environment and

what's required and the sensor type it

sends the information to computers with

the seada software

so this helps the systems monitor

interact and control a variety of

equipment

prevents outside attacks the um seida

systems are segmented from the rest of

the network

and in addition they have the firewalls

installed

you'd need probably help from a

specialist and design company and

probably installation as well because

it's kind of outside the purview of the

normal Network Engineers roles

um old and outdated compute systems

often referred to as Legacy these May

well be running applications and you'll

you could see this a lot if you do a new

network Consulting you'll go to

companies that are just running in Old

software and they want to keep it

because it still works and it's due to

the cost and all of the heartache of

having to upgrade and translate all of

the data

these systems can't be taken out of

service usually but because of the age

they're more vulnerable to attacks and

because of the lack of support and the

support means there's no more security

patches

so basically we'll come back into back

to segmentation and it's important to

segment these from the rest of the

network

service in the network for Public Public

Access would normally restrict access

this is classic example is at a public

library where customers come in and want

to use the systems but obviously you

don't want them to have visibility to

the back end systems where customers

data is kept and people can get books

and make payments and all that sort of

stuff

so you'd segment the servers and

resources used by employees on a private

Network public access to the public

and net Network segmentations critical

situations if a private network is

restricted only to employees it's less

prone to outside attacks probably

certainly obvious here in a public

network even if the server is

compromised it won't actually affect

your internal private Network so you

could do your troubleshooting and

resolution without worrying about

um affecting your critical Business

Systems

uh testing patches and updates for

applications should be carried out in a

test the environment it's often called a

test bed where you've got a copy of your

devices

and you could even be running them

virtually

and it's all done in order to prevent or

foresee problems on your live equipment

a honey pot is a decoy server set to

lure attackers studies there and

methodology and how they break into the

systems gathers for our zinc forensic

information and it can be used in the

event that you actually prosecute

somebody

designed to be a little bit more easily

exploited exploited than the actual

production server so this would probably

be the first device discovered by the

attackers

has attackers activities logged to get

insight into their sneaky little methods

okay an early part is a network segment

that contains more than one

um honey pot or only net sorry

so the honey net would normally look

like a normal operational Network for

the attacker

and it'll make the attacker spend more

time in the system which gives you more

time to analyze what they're doing and

where they're coming from

all right so we've covered segmentation

physically logically uses of it and

critical situations that's the end of

the presentation thanks for watching

[Music]

Network routing and IP addressing IP

addresses and conversion

so welcome to this module we're going to

cover IP addresses and conversions and

in some of the previous modules we

talked about a lot of the Technologies

and theories and protocols that make up

computer networks and so here we're

going to discuss some of the more

important aspects of networking

specifically the IP address so this

module is going to begin by introducing

us to some of the specific protocols

that are found within the tcpip protocol

Suite that you need to know about for

the network plus exam and these are TCP

and IP and a little more depth we

mentioned them briefly when we talked

about the TCP model and then we're going

to describe UDP which is a connection

less protocol then we're going to look

at ARP and rarp two versions that allow

us to basically or two protocols rather

that basically allow us to map Mac

addresses to IP address and which are

basically responsible for routing in

general and after that we're going to

look at two management protocols one

called icmp which I introduced to you in

previous modules and I said it was

related to the Ping a utility we're

going to learn a little more about that

and then igmp which is uh slightly

different has to do more with

multicasting and unicasting and then

we're going to continue by outlining uh

IP packet delivery processes and we're

going to finish off the module with a

bit of an introduction into binary and

decimal conversions so that later on we

can talk a little more in depth about IP

addressing and how

something called subnetting Works which

is going to require us to understand the

difference between these two ways of

writing our numbers and after we have

covered all these topics we're gonna

have a fundamental understanding of Ip

that's going to prepare us for some of

the more in-depth topics as I just

mentioned in the following modules

so let's begin by taking a look at two

of the most important protocols that

make up the suite TCP and IP now in

previous chapters we briefly described

these two but we still need to take a

closer look at them to assure that we

have a complete understanding of the

many different protocols that are found

in our protocol Suite so first for those

applications and instances that depend

on data to be reliable in terms of

delivery and integrity the transmission

control protocol or TCP and I'm just

going to write out

transmission

control

protocol is a really Dependable protocol

and provides a number of features first

it guarantees that data delivery and

besides

um guaranteeing that delivery it also

has a certain amount of reliability it

also offers flow control which as we've

mentioned in the past assists ascending

station in making sure it doesn't send

data faster then the receiver can handle

this function also is going to assist in

the reliability of data because it

ensures that there isn't any data lost

due to overloading

um

the receiving station

now TCP also contains something called a

checksum mechanism and what this does is

it assists with error detection the

level of error detection isn't as strong

as that of some of the lower layers and

you recall that this is in the transport

layer of the tcpip stack

but it does catch some specific errors

that may go unnoticed by other layers

and and by the way this checksum

basically it's it sort of has a number

that it creates

based on the data and it can check that

number at the beginning and at the end

to make sure we haven't lost anything

now this protocol attempts to alleviate

MTU if you recall uh what we talked

about with MTU there mismatches on the

data link layer by establishing maximum

segment sizes that can be accepted by

TCP this is also going to reduce what we

talked about earlier that MTU black hole

now further examining IP or the Internet

Protocol

which is aptly name and exists at the

internet

layer unlike TCP IP is characterized as

being connectionless or a best effort

delivery which is also like UDP which

we'll see in a second it outlines the

structure then of information which is

called datagrams or packets

and how we're going to package this

stuff to send it over the network this

protocol is more concerned with source

to destination navigation or planning or

routing as well as host identification

and data delivery solely by using the IP

address so this is slightly different

from TCP which is doing stuff in a much

more different way now IP is used for

communications between one or many IP

based networks and because of its design

it makes it the principal protocol of

the internet and it's essential to

connect to it so unless we are using IP

address in today's day and age we will

not be able to connect to this big thing

called the internet now the terms

connection less and connection oriented

relate to the steps that are taken

before the data is transmitted by a

given protocol whatever that protocol

might be with TCP we're looking at

connection oriented and of course with

IP we're looking at connection less

and for instance the connection oriented

protocol is going to ensure a connection

is established before the sending of

data meaning it is oriented towards a

connection whereas a connection less

isn't going to doesn't matter if there

is a connection established already

so the next protocol which is also

connection last that we want to talk

about is something called UDP now since

we have many applications and their

functions depend on data being sent in a

timely manner TCP and its connection

oriented properties hinder their

performance in these cases we're able to

use something called

UDP again the user

datagram protocol

and UDP is connection last just like IP

is

and it's a that means it's a best effort

delivery protocol so with TCP if packets

get delayed or if they're needed to be

resent due to a collision the TCP on the

receiving end is going to wait for the

lost or late packets to arrive and with

some sensitive data delivery this is

going to cause a lot of problems and UDP

is what we call a stateless protocol

which prefers the packet loss over the

delay in waiting so UDP is only going to

add a checksum to the data for data

Integrity it's also going to uh address

port numbers for specific functions

between the source and the destination

nodes such as UDP Port 53 for DNS which

is one that you should remember from an

earlier module Now udp's features make

it a solid protocol and it's used for

applications such as VoIP or voice over

IP

and online gaming this makes sense

because we don't care if every single

little packet arrives what we want is we

want the speed with which

UDP is going to deliver stuff obviously

if we miss a couple packets in voice

that's okay they drop but we don't want

to have to wait until the next packet

arrives that's going to actually cause

much more of a delay and so we're going

to use this one in more VoIP and online

gaming purposes now the next protocol we

want to be familiar with

is called ARP and it's also necessary

for routing ARP or the address

resolution

protocol and

the reverse

address resolution protocol our request

and reply protocols that are used to map

one kind of address to another

specifically ARP is designed to map IP

addresses you need addresses that are

necessary to tcpip communication to Mac

addresses which are also known as we've

discussed in the past as physical

addresses

and again IP addresses

work on the networking layer

or in tcpi PV internet layer

whereas Mac addresses operate on the

network interface layer of TCP which in

OSI would be the data link layer

layer 2.

now in tcpipnetworking

ARP operates at the lowest layer the

network interface layer in total whereas

in the OSI model we say that it actually

operates between

the data link layer

and the physical layer

and this is because it wasn't designed

specifically for the OSI model it was

designed for the tcpip model now ARP and

rarp play very important roles in the

way networks operate the computer wants

to communicate with any other computer

within the local area network the MAC

address is the identifier that's used

and if that device wishes to communicate

outside of the local area network the

destination Mac address is going to be

that of the router so the our process

works by first

receiving the IP address from IP or the

Internet Protocol

then ARP has the MAC address in its

cached table so the router has what are

called ARP tables

that link IP addresses to Mac addresses

we call this the ARP table

so it looks in there to see if it no if

it has a MAC address for the IP address

listed

it then sends it back to the IP if it if

it does have it and if it doesn't have

it it broadcasts the message it's sent

in order to resolve what we call resolve

the address

to a MAC address

and the target computer with the IP

address responds to that broadcast

message with what's called a unicast

message and we've discussed that that

contains the MAC address that it's

seeking

ARP then will add the MAC address to its

table so the next time we don't have to

go through this whole process

and then it Returns the IP address to

the requesting device as it would have

if it just had it

now RP is used to do the opposite that

is to map Mac addresses of a given

system to their assigned IP addresses

and it sort of works in Reverse from all

this now that's a very general overview

of ARP and rarp and if you were to go

into Cisco certifications for instance

you go a little more in depth into this

but for Network plus this is really

where we need to stop with this protocol

so the next protocol I want to talk

about is icmp which is also called the

internet

control

message protocol

it's a protocol designed to send

messages that relate to the status of a

system it's not meant to actually send

data so icmp messages are used generally

speaking for Diagnostic and testing

purposes and they can also be used as a

response to errors that occur in the

normal operations of Ip and if you

recall one of the times that we talked

about that was for instance with the MTU

black hole

when that icmp message couldn't get back

to the original router now many Internet

Protocol utilities are actually derived

from icmp messages such as Tracer or

trace route

path ping and ping and we'll talk about

these in a little more depth than if you

were around for uh a plus we definitely

talked about these two quite a bit icmp

is actually one of the core Protocols of

the IP suite and it operates at the

internet layer which as you recall is

tcpip

second layer

now icmp is a control protocol used by

networked computers and operating

systems and the most common utility that

we're going to see is what's called

ping which we've talked about which uses

what are called icmp Echo requests and

they reply to determine connection

statuses of a Target system so I could

ping a specific system to see if it's on

the network of course there are some

reasons why the icmp as we've talked

about might not make it back to me or

it's configured not to respond perhaps

through a firewall finally we need to

talk about igmp or the internet

group

management protocol

it should not be confused with icmp it's

slightly different

it is used to establish memberships for

multicast groups now multicasting is

where a computer wishes to send data to

a lot of other computers through the

internet by identifying which computers

have subscribed or which ones wish to

receive the data we looked at this

earlier and determined that routers

determine a multicast group now in a

host implementation a host is going to

make a request for

and igmp implemented router to join the

membership of a multicast group

certain applications such as those for

online gaming can use igmp for what are

called

one-to-many Communications the one being

the game server and the many being all

of those end users that have subscribed

to the gaming session

so those routers with igmp

implementation periodically will send

out queries to determine the multicast

membership of those devices within range

and then those hosts that have

membership are going to respond to the

queries with a membership

report

now the process of delivering an IP

packet is simple

it begins with resolving the name of the

host to its assigned IP address like we

talked about with arp and the connection

is established by a service at if you

recall the transport layer

now after the name resolution and

connection establishment the IP address

is then sent down to the internet layer

and the next step is where the IP looks

at the subnet mask which we've talked

about in a plus and we'll talk about

more of the IP address to determine

whether the destination is local to the

computer on what we say is the same

subnet or whether it's remote or on

another Network after this determination

is made then finally the packet is

routed and delivered

okay so we now understand TCP a little

more fully some of the protocols that

are dealt with in great detail and how

IP packet delivery works so let's talk

about binary and decimal which are going

to be really important when we get into

what's called subnetting and it's just

good to know as an I.T professional

anyway

specifically

understanding binary or how to convert

binary which is the number of computers

the way computers talk to decimal which

is the way that we deal with numbers and

decimal to binary

pertains to a lot of different aspects

of as I just mentioned networking so to

begin with binary is the name implies

from buy is what we call a base 2 system

more commonly we used a base 10 system

decimal

now this means that we have 10

possibilities for every place value we

have between a zero and nine you add

that up there are 10.

now with binary there's only two options

either zero or one

so we can either have a single zero or a

single one and that's what we call a DOT

a binary digit or

a bit

so the binary number has Place markers

that are similar to the base 10 system

for instance if we have a a decimal base

10 numbering system the second place

Mark designates the tens if we imagine

that there's a

uh period or a decimal right there

the third designates the hundreds and

then we move to thousandths and ten

thousandths and hundred thousandths and

so on and so forth and in each one of

these we can have anywhere from zero

to 9 and that's ten options in each one

of those spots

now in base 2 numbering system which is

binary we have only two options a one or

a zero in either one of those places and

in computers especially in a lot of Ip

addressing we really deal with the

difference between uh eight different

places

so we're going to call these eight and

octet

so this eight Place binary digit is

referred to as an octet because there's

one two three four five six seven eight

of them and you'll see these numbers pop

up over and over again so this is really

as far as you need to know for binary

although you can go even further so if

we look at this octet from the right

side to the left

the first place Mark is what we call

2 to the 0 power

right if we were talking about this in

tens this would be the ones place y

because it's 10 to the zero power which

is ones anything taken to the zero power

is one

next we have 10 to the first Power which

is going to equal 2. if you recall we

call this the tens place 10 to the one

power means 10 by itself is 10.

then we have 10 to the second power

which is 4 and if you recall in decimal

this is 10 to the second which would be

10 times 10 which is 100 you can see

where this is going

so 2 to the third is eight two to the

fourth equals 16 2 to the fifth equals

32 2 to the 6 equals 64 and 2 to the 7

equals 128. so each one of these Place

markers is equivalent

to this number whether it's turned on or

off

now to help clarify this a bit each

place here

has one of two options correct because

it's base two if it's off that means

it's a zero as you see right here and

the numbered means it's not being

counted so we don't count any of these

numbers we've just calculated so if all

the bits are off that means that we have

a number of zero

if all of the bits are on then this

means we add each of the numbers

together

so we get 128 plus 64 plus 32 plus 16

plus 8 plus 4 plus 2 plus 1 which equals

255. now believe it or not you can

create any combination of numbers from

just binary you don't need decimal we're

going to see that in just a second

so for example

let's say the binary number is uh

zero zero zero zero zero one one one

well in this case the 128 64 32 16 and 8

Bits are all off the only ones that are

on are four two and one and if we add

those together four plus two plus one

we'll get 7.

4 plus 2 is 6 plus 1 is 7.

if we take another number

say 0 1 1 0 0 1 1 0.

then this is going to equate to 102. why

64 plus 32 equals 96 plus 4 equals 100

plus 2 equals 102.

so it's pretty simple you just take the

number with the ones under it and add

them together so now that we've

converted binary into decimal a number

that we all know let's go ahead and see

if we can convert the other way decimal

to Binary now for this process we're

going to use the same exact chart

that we just saw

with the binary conversion

and this chart is going to help us

visually represent all the binary digits

which is why I like it in their

placeholders and it makes it a lot

easier so for decimal to Binary we

simply go from left to right and break

down the number until we reach the zero

so let me break that down a little bit

for instance if we take the number 128

right this is pretty easy to convert we

plug it into this chart how many times

does 128 go into 128

one time

if we take all the others and we

subtract them we're going to have zero

right because now 128 minus 128 is zero

that leaves us with our binary number

one zero zero zero zero zero zero zero

which is equivalent to 128.

now if we take a look at a different

number let's say the number 218

this is going to take a little more math

does 218 go in does 128 go into 218 it

certainly does

so 218 minus 128 has a remainder

of a certain amount which is 90.

does 64 go into 90 it does we now have a

remainder of 26. does 32 go into 26 no

it doesn't so we put a zero

does 16 go into 26 yep it does which

leaves us with a remainder of 10.

does 8 go into 10 it does which leaves

us a remainder of 2 does 4 go into 2 it

does not so that leaves us with zero we

still have our two does two go into 2

yep and then do we have anything left

over nope we're at zero now so we have

zero if we now add all those up this is

our binary number one one zero one one

zero one zero now while this might seem

like a fairly long process it's

important to understand how this works

because when we get into subnetting it's

really going to become important so we

can have a better understanding of

networking in general

so just to recap everything we've talked

about we described these protocols in

the tcpip suite first TCP transmission

control and IP Internet Protocol one is

connection oriented

and the other is

connection less

meaning that it just is worried about

delivery remember IP is what is

responsible for that IP addressing

UDP is also connection less

similar in some ways to TCP but it's not

connection oriented

then we had ARP and reverse ARP address

resolution protocol which job is to map

IP addresses

to Mac addresses

we talked about icmp which is what we

use

when we're dealing with the status of a

system

internet control message protocol

and then we talk about igmp the internet

group management protocol which is more

dealing with multicast groups

we then talked very briefly about the IP

packet delivery process which was pretty

simple right it's packaged it's sent we

determine where it needs to go once it's

determined where it needs to go it's

sent there

finally we explained the binary

conversion which is going to be really

important for IP addressing including

how to go from binary

which is a base 2 system

to decimal

which is a base 10 system

and Back Again

[Music]

Network routing and IP addressing IP

addresses and subnetting

so having discussed IP addressing and

routing in general we're now going to

further examine IP addressing and the

methods of logically not physically

dividing up our networks this way we can

keep not only better track of all the

devices on the network but also organize

them for security performance and other

reasons after we complete this module

we're going to have a better

understanding of how our network devices

are identified both by other devices and

by individuals such as ourselves since

we're not computers

so first we're going to identify what a

network address is versus a network name

one the network address is for other

devices a network name is really for us

since it would be difficult for us to

remember all these numbers much like

using a phone number and a cell phone

next we're going to describe the ipv4

addressing scheme and ipv4 is important

to know because even though we have a

newer version IPv6 ipv4 is still

deployed in most situations and it's

covered to the most extent on network

plus when we get to IPv6 which is

different version six there are a lot of

benefits then we'll describe it later

but really understanding ipv4 is really

important after we take a look at that

we're going to look at subnetting and a

subnet mask you might have seen this and

these are the numbers and we've probably

mentioned to them in the past such as

255.255.0.0 and so on and so forth and

we're going to describe how this allows

us to separate out the network ID from

the node ID or the device's ID or

address from the networks address much

like our ZIP code versus our street

address after that we're gonna just

describe the rules of subnet masks and

their IP addresses and knowing binary is

really going to help us understand all

of this stuff

after that we're going to apply a subnet

mask to an IP address using something

called anding which again gets back to

Binary and might even remind you of

something you learned in high school

this ending principle which is really

going to come in handy again this is

something that we only have to do now

with ipv4 IPv6 doesn't have to do it and

we'll describe why finally we're going

to take a look at what are called custom

subnet masks which are slightly

different from these default ones the

255 to 255 to 255s and so on so having

said all that let's get into it by

looking at Network addresses and names

so let's begin by looking at how nodes

on a network are identified specifically

on the Internet or network layer if you

recall the network

layer

is layer 3 of The OSI model

and the internet layer

is layer 2 of the tcpip model

so to begin a network address is

assigned to every device and I think

we've discussed this that wants to

communicate on a computer network the

network address is actually made up of

two parts the node portion that belongs

to the specific device and the network

portion which identifies what network

the device belongs to I think I've just

described this as a zip code which

describes the sort of network or the

area you're in versus your street number

and your street address which is

specific to where you live this address

is what is used by devices for

identification and as it's only made up

of numbers whereas a network name is

made up of

um letters and such the real reason

being readability we would have a lot of

trouble remembering we already have

trouble remembering a phone number but

if you imagine remembering a whole

binary number a set of numbers where

there infinite possibilities unless

you're using it a lot it's easier to

remember a name such as the conference

room laptop or resource server one than

it is to remember an IP address which

might be something like 132.168.56.43

especially when there are a lot more

computers involved the names become a

lot easier so the network named is

actually mapped to the address or the IP

address by one or another naming

services and some of these we've

discussed now as devices only

communicate with each other by their

Network address the naming service is a

really crucial to the operation of a

network there are three different

network Services used that you should be

aware of the first DNS which we've

mentioned before also called the domain

name service is an Aiming service that's

used on the internet in most networks

it's what allows for instance you to

type in Google

dot com which we would call a fully

qualified domain name and it will

translate that to the IP address of

Google whatever that might be

the next naming service is Windows

specific and it's called wins or the

windows internet naming service it's

really outdated and it was used on

Windows networks the only reason I

mention it is you might see it mentioned

in a test question and it might help you

but you're really not going to see it

used in the field much anymore and

finally we have one called net bios

which is a broadcast type of service

that has a maximum length of uh 15

characters

and it was used or still is used to a

certain extent on Windows networks as

well a good understanding of all of

these Network identification aspects

addresses and names is important at this

very fundamental level

so now that we sort of have a general

overview of these let's take a look at

some of the specific type of network

addressing specifically

ipv4 now ipv4 ipv4 addresses is a very

important aspect of networking for any

administrator or technician or even just

you know it guy to understand

it is a 32-bit binary address that's

used to identify and differentiate nodes

on a network in other words it is your

address on the network or your social

security number with the ipv4 addressing

scheme being a 32-bit address and you

can see if we counted each one of these

up remember a bit is either 0 or 1 and

we can count up there are 32 of these

this means that there are theoretically

up to

4.29 billion

addresses available now that might not

sound uh like we're ever going to hit

that but in fact we've already gotten

there and so part of the problem is how

do we share 4.29 billion devices with

our 4.29 billion addresses with even

more billions devices in the world so

this 32-bit address which is why we've

had to develop another one called IPv6

but anyway I digress the 32-bit address

is broken up into four octets this makes

it easier for people to remember and to

read

and you can see those here and if you've

ever seen like a

192.168.0.1 those are the four octets

this system and structure of these

address schemes is governed and managed

by two standard organizations one is

called the a i a n a

which stands for the internet assigned

numbers Authority and the other is

called the rir or the regional internet

registry I wouldn't worry about

memorizing these I'm just mentioning

them so you know sort of who's coming up

with all this stuff

now every device on the network is going

to have its own unique address

so there are two types of addresses in

general one is called class full and

these are default addresses and the

other are called class less which are

custom addresses we're going to talk

about the class less ones in a later

module and we're going to Define both of

these in Greater detail a little bit

later on

as a network address it's also made up

of two parts the network portion and the

node portion let me just erase all this

writing here so you can see exactly what

I mean in order to tell now in this

section

you can see the network portion are the

first two octets and the node portion of

the last two octets but that is not

always the case in fact if we were to

just take those away for a second uh and

this is how the computer looks at them

we can't actually tell which is which

and that's why we need something called

a subnet mask the subnet mask allows us

to determine which is the network

portion and which is the node portion

that way we know for instance where the

area code of the phone number begins and

the rest of the number ends so the

network portion would be like the area

code of your phone number or the

international code it tells you which

network that is on the Node portion

tells you exactly which phone on that

Network we're going to try reaching out

to so we're going to further logically

again not physically divide a network

into smaller sub networks called sub

Nets

now this logical division is beneficial

because of three reasons one it can

effectively increase the efficiency in

packet routing because if I know that my

information is destined for a specific

Network I don't have to bother with

asking let's say 5 000 or 5 million or

five billion computers if I'm meant for

them I can go directly to the network

where I want to go just like with area

codes and phone numbers the next is it

allows for better management of multiple

networks within a single Organization

for instance if I'm a network

administrator it might be easier to have

separate subnets so I can organize who's

on which subnet so that way not only are

things going to be routed more

efficiently for that person but it's

easier for me to manage on paper and uh

in my administrative duties and finally

it potentially offers a certain level of

security since I'm only going to be able

to access easily information that's on

the same net work or sub Network that

I'm on

now a subnetted ipv4 address is actually

comprised of three different parts the

netid

the host ID

and the subnet ID

now if a device on a subnetted tcpip

network wants to communicate it's going

to need to be configured with an IP

address and a subnet mask and we'll look

at these in just a second the subnet

mask is what is used to identify the

subnet that each node belongs to this

also allows us to determine which

network it's on connectivity devices

such as routers or upper layer switches

and we're talking about layer 3 devices

here and remember layer 3 devices look

at IP addresses

not just Mac addresses

are used on the borders of these

networks to manage the data passage

between and within the network that's

how we're going to get better routing

efficiency easier management and

potentially make it more secure because

if I have any one network and I have a

let's say a switch

we'll put this a switch and it has four

computers on it and then I have another

switch

and these are layer 2 switches okay

and each of these let's say we have our

different subnets then I'm going to

divide these up

by a router which now is going to make

sure that data that's going here kind of

gets bounced back unless it's meant for

this guy and this way we're really

reducing the traffic on it

now a subnet mask is like an IP address

a 32-bit binary address broken up into

four octets and a dotted decimal format

just like an IP address

and it's used to separate the network

portion from the node portion I'm going

to show you how that works in just a

minute and it involves a little bit

knowledge of binary which we've already

talked about so the subnet mask and that

name mask sort of lets you think of it

as being put onto the IP address is

applied to that IP address and removes

the node ID the subnet mask therefore

eliminates removes an entire octet of

the IP address by using eight binary

ones or 255 in decimal format meaning

that this 255 if we add it up in binary

would be one two three four five six

seven eight

one two three four five six seven eight

one two three four five six seven eight

and then this would be one two three

four five six seven eight so meaning

that a 255 equals eight

ones which is the reason why an IP

address can never be 255. and if this is

a little confusing that's okay we're

about to clarify that in just a second

so IP addresses IP address assignments

and subnet masks all have to follow a

certain set of rules I'm going to

describe the rules and then I'm going to

apply them so if some of this is a

little confusing or over your head keep

paying attention keep with me and I

think it's going to clarify itself

the first is that the ones in a subnet

mask will always start at the left

meaning the first octet will always be

255 or 8 binary ones so my I my subnet

mask I'm always going to start at the

left when I'm writing it out

this says that the first octet is going

to be 255 which means 8 Bits

now the zeros of the Mask will always

start

at the one bit

or all the way on the right

meaning that I'm going to have zeros

from the right

and ones from the left

and the ones in The Mask have to be

adjoining adjoining or con consistent or

continuous or contiguous whichever word

you want to use meaning once there is a

zero we cannot then go back to ones so

we're not going to see like this sort of

thing happen

in fact we have to have continuous ones

from the left and continuous zeros from

the right

this is the only way a subnet mask is

going to work and I'll talk about why in

just a minute

also if there is more than one subnet on

a network every subnet has to have a

unique network ID and I'll explain this

in a bit but it makes sense if I have a

different network IDs

then I'm not really I'm sorry if I have

similar Network IDs then I'm not really

dealing with multiple networks I'm

dealing with the same network

now assignment of IP addresses have to

follow a few more rules so these are the

subnet masks first there cannot be any

duplicate IP addresses on the network

this means that every Network every

device has to have its own unique

IP address we cannot have more than one

device with the same IP address if we do

they're not going to communicate because

the switches won't know where to send

packets next if there are subnets every

node must be assigned to one of them

meaning that every address every IP

address has to be assigned to a specific

Network

now the address of a known cannot be all

ones or all zeros remember all ones

would be 255. all zeros would be just

0.0.0.0 so I cannot have an IP address

that is either

255.255.255 or that can be

0.0.0.0 and you'll see why when we get

to the mathematics of this in just a

second it's because then I would never

be able to determine a network ID from a

node ID

finally and this is something you sort

of have to remember the IP address can

never be

127.0.0.1 we've talked about this in um

a plus but that's because this is what's

called the loopback it's a reserved IP

address specifically for yourself be

like saying me myself or I I cannot have

a a

127.0.0.1 IP address assigned to a

device because every device calls itself

127.0.0.1

now besides understanding these rules

which are a bit abstract I think we need

to know how to apply them and how to

apply a subnet mask to an IP address I

think it's going to make some of these

rules a little clearer so let's take a

look at those now when a subnet mask is

applied to an IP address

the remainder is the network portion

meaning when we take the IP address and

we apply the subnet mask and I'll show

you how to do that in a second what we

get as a remainder what's left over is

going to be the network ID this allows

us to then determine what the node ID is

this will make more sense in just a

minute the way we do this is through

something called anding ending is a

mathematics term it really has to do

with Logic the way it works is and you

just have to sort of remember these

rules

one

and one

is one

one

and zero

is zero and the trick there is that that

zero is there

zero

and one

is zero

and zero

and zero is also zero so basically what

anding does is allows us to hide

certain

um address certain bits

from the rest of the network and

therefore we're allowed to get the IP

address or rather the network address

from the node address

so let's take a look at this for just a

second let's say we have an IP address

162.85.120.27 and we have a subnet mask

of 255.255.255.0

now let's take a look at how this works

when we move it into binary

162.85.120.127 equals this in binary and

if we wanted to write out these places

again if you remember we had this was a

base two

right so these are the place settings

I'm just going to write these out real

quickly and then I'm going to erase it

all

okay

and so we get one

two four

eight

sixteen thirty two sixty four

128 and it's good to sort of commit

these to memory therefore the reason

this is one one one is we take that 128

we add it to 32 and we add it to the 2

because those are the bits that are on

and when we add 128 plus 32

we get 160

plus 2 gives us 1 62. so it works out

and you can see my math is correct here

I'm going to erase all this now try to

remember this and thing in here for a

minute

now if we convert

255.255.255.0 into binary we've already

talked about this we're going to get

all these ones and then because this is

zero we're gonna get zero now if we

apply the anding principle

this is what we're going to get

anything with one and one turns into one

anytime we see a one and a zero we're

going to get a zero and if we apply this

out

here's what we get now because we have

all these zeros here it's basically

going to block all these ones from

coming down and coming through

right they all turn into zero

so if we convert this back into a

decimal we now get 162.85.120.0

basically this is pretty simple to see

we can see that the 162 drops down the 8

5 drops down the 120 drops down because

of this ending that we just talked about

and the 27 gets blocked might be zeros

and so we can determine

that the

162.85.120 is what we call

the network

ID

Now by looking at it this way we can see

then that the network portion of the

address is going to be the first three

octets as we just pointed out and the

node portion is going to be the last

octet

so this is the first step in subnetting

and it tells us a lot of things about

the networks just by knowing the IP

address and the subnet mask a technician

can now discern a lot of things such as

what portion is the network ID what

portion is the node ID

and therefore what is my first usable IP

address and what's my last usable IP

address that I could start to give to

devices

I can also determine stuff like what we

call the default gateway which we'll

look at in a second

and

the broadcast address which will also

look look at not in a second then in the

next module

now there are three default subnet masks

as you can imagine

and these have to do with what we call a

class uh a class full IP addressing

system and we'll talk about that next

the next module but the default subnet

masks are 255.0.0.0

just going to go with the class A and

we'll talk about that

255.255.0.0 and 255.255.255.0

what you can see is if you have a

default subnet mask then you know

immediately just by looking

what the network address is and what the

node address is

as you can imagine

if I have this as my network address

I can have a lot of Networks and only so

many nodes this one I have

more nodes a little bit less networks

and this one I have a lot of nodes but

fewer networks to divide them up on

now would be great if all subnet masks

were as simple as this we wouldn't even

really ever have to break it down into

this binary sort of coding because you

could just look at it and say oh it's

255 I know they're all going to be ones

I know that's going to end out and

therefore I know it's going to end up

right here

but unfortunately this is not always the

case sometimes we have what are called

custom subnet masks Now by using a

custom subnet mask we can actually

further divide or subdivide our IP

address and in these cases it can be a

little more difficult uh and so

converting to Binary is actually

necessary to break it down custom subnet

masks are created by what we call

borrowing bits

from the host portion to use to identify

the subnet motion so you can see we've

just borrowed a bit this one right over

here

now keeping in mind that the subnet mask

rules allow us to borrow bits from the

node portion and give them to the

network portion the bits from the left

to the right of the portion

like this

are switched on

now turning this bit on means we now

have different values for the subnet

mask instead of just 255

.255.

255.

dot zero we know this is no longer zero

right so this is actually now going to

be

128.

and we can have a a number of these and

if you keep adding over to the right

so 128 and then we added 64. we'd get

192 and so on and so forth so we can

actually have a number of custom subnet

mask values in the last octet and that's

those are these and so you can see in

this case uh it's not really going to

make much of a difference when I I'll do

all the binary bidding because

you see that the zero and the zero is

still going to become a zero here and so

all of this is really going to look the

same and so our Network portion is

actually going to look the same as it

did before we have the same network ID

as we did before but let's say that this

was actually uh you know this number by

the way is the same as the one we had

before

162.85.120.27 if this was instead

162.85.120

dot I don't know one

128 we're gonna have an issue because

this is going to be on these would say

let's be off and when they come down

this is going to turn into a zero as

opposed to that one dropping down and so

it's going to change what our IP address

in the end looks like and so we actually

need to do some backward engineering to

get to our subnet mask now this is all

really complex and when we get into if

you ever get into Cisco you'd really

have to know this but for our purposes

you really don't need to know this that

in depth all right so just to recap what

we talked about here we got a basic

understanding of a lot of things not too

in depth and you might need to re-watch

this video to really get it and maybe

even do a little bit of exercises on

your own

first we talked about the difference

between a network address and a network

name remembering that the three network

name services that match a name such as

Bill's laptop to an address which would

be something like 192.168.0.1

uh we can use either DNS the domain name

service which is the most popular one

something called wins which is specific

to Windows or net bios also a Windows

based

naming system

the one we want to be most familiar with

is this this one's not really used

anymore netbios is still used in certain

instances especially in older networks

we then talked about the IP version 4

address and the things that it requires

including and remember a ipv4 address is

that 32 bit broken up into four octets

the reason it's called an octet is

because we have eight times four

gives us that 32 and we break it up so

for instance 192 is going to break down

to a certain amount of bits okay

we also talked about defining subnetting

in a subnet mask which the most

important thing it does is distinguishes

our Network

from our node

ID in other words what's our area code

and then what is our phone number

we can have the same phone number

in different area codes but they go to

very different people

we also talked about the rules of subnet

masks and IP addresses we can only have

one IP address

on any network

and we can not use

127.0.0.1 because that is what we call

the loop back address

as far as for the subnet mask remember

that all ones have to be continuous from

the left

and zeros have to be continuous from the

right

our defaults our 255.255.0.0.0

and then 255

I'm sorry I think I just said

255.0.0.0

285.255.0.0.0 and

255.255.255.0 those are our defaults and

so we talked about applying a subnet

mask using something called anding

and we looked at how that divides up

again the network ID from the node ID

and we saw that in practice finally we

talked very briefly about custom subnet

masks something that we don't have to

get very much into but we talked about

how if we had 255.255

.255 dot for instance 128 we could have

these sort of sub subnets or these uh we

could break it down even further and

therefore we could start to do a lot

more stuff and in the next module I'm

going to talk about this in a lot more

detail and why we would want to do it

[Music]

thank you

Network routing and IP addressing

default and custom addressing

so we described in the previous module

subnetting how to determine the network

from the node ID and we talked

specifically about ipv4 and we're going

to continue talking about ipv4 a little

bit more first by defining the default

ipv4 addressing scheme now some of this

we sort of touched on in the previous

module and some of the stuff we're going

to talk about right now is going to

probably help clarify that and so it

might not it might even help to go back

and watch the previous module after

watching this one after that we're going

to talk about the reserved or restricted

ipv4 addresses one of the ones we've

already mentioned is what we called the

loop back or

127.0.0.1 that's an example of a

reserved IP address a restricted IP

address and so we're going to talk about

those in more depth and some of the ones

that some of the ranges that are

restricted and why they are then we're

going to discuss what are called the

private address addresses and we're

gonna talk about these specifically

because these are different from public

IP addresses uh one you might be

familiar with is the

192.168 uh public at a private addresses

rather and you'll this is going to

explain why every router that you

purchase that you know electronics store

has this as its default not everyone but

a lot of them have this is the default

IP address and yet we talked about how

you can't have more than one IP address

with any device and so we're going to

describe why with private IP addresses

this is the case and we'll talk about

some other private IP addresses as well

now we're going to talk about the ipv4

formulas and that's the that's what

allows us to determine how many

hosts

and networks are permissible based on

the type of IP address the class that

it's in and the subnet mask that's

supplied and this will help us also

determine and talk about in a second uh

why we might want to use custom subnet

masks and custom IP addresses

so then we're going to talk about the

default gateway is this gets back to

actually this right here it is the

device which the any node needs to know

in order to get out to the network and

to the rest of the um the rest of the

world

finally we're going to talk about custom

IP address schemes

vlsm and cidr these are a little more in

depth but these really get back to the

subnet masks and why we can apply those

uh how we can apply sort of specific

subnet masks to things and we'll look at

this thing which you might have seen

cidr which is has to do with why there

might be a slash after an IP address

which really gets to the number of bits

it has and we'll talk about that just a

minute now aside from being an aspect

that's covered in many areas of the

network plus exam understanding the

classes in a default IP address scheme

is really important for us and this gets

back to uh right here so let's talk

about remember we talked about class

lesson class full we're going to talk

about the classes that exist in an IP

address right now so as we learned in

previous modules the ipv4 addressing

scheme is again 32 bits broken up into

four octets and each octet can range

from 0 to 255.

now the international standards

organization icann which we've mentioned

in a previous module is in control of

how these IP addresses are leased and

distributed out to individuals and

companies around the world now because

of the limited amount of IP addresses

the default ipv4 addressing scheme is

designed and outlined which what are

called classes and there are five of

them that we need to know now these

classes are identified as a b c d and e

and each class is designed to facilitate

in the distribution of IP addresses for

certain types of purposes now the First

Class A Class A allows you to have is

designed for really large Networks

meaning that it does not have a lot of

networks because we only have a few of

them and that is because a Class A Range

goes from one

to 127.

in the

first

octet meaning that the remaining octets

are reserved for nodes and so we see

that we don't have a lot of networks we

only have 126 networks one to 127.

but we do have up to 16

.7 or 0.8 around about million net I

nodes that can be on

this network and so uh we have so many

nodes for so few uh networks and so this

is really for very large large networks

and there are some specifically reserved

addresses in this as well we'll talk

about those in just a minute now with

class B here we have

128 to 191.

and these are called Class B they allow

for a lot more Networks

and fewer nodes which makes sense

Now the default subnet mask for class A

which might make this a little clearer

255.0.0.0 whereas for a class B it's

255.255.0.0 now as you can tell the

class is actually determined by the very

first octet the number in the first

octet

and it's important to then therefore

memorize these numbers because you'll

see on your exam they'll ask you which

class is this IP address a part of if

it's between 1 and 127 you know it's a

Class A if it's between 128 and 191 you

know it's a Class B if we get to a class

C now we have a lot of networks and not

a lot of nodes and you can see that

these are 192 to 223 in the first

octet and the default subnet mask

for this is going to be 255 to

255.255.0 and if you remember that gives

us only this octet for nodes and all of

these octets for networks this is

usually one of the most recognizable for

home networks because we have the

192.168.0.1 for instance that is going

to obviously fall into this class C now

there are two other classes they're not

very common but they're important to be

able to recognize they're a Class D i p

addresses which are only used for what

we call multicast Transmissions

and these are for special routers that

are able to support the use of IP

addresses within this range you don't

really need to worry about this for much

application unless you're dealing with a

lot more advanced stuff and these deal

with 224 to 239

finally we have class E which is from

240 to 255 and these are really for

experimental reasons so we're really not

going to see these in much play the ones

you really want to be familiar with

are these first three classes a b and c

remember 1 to 127 is a class A 128 to

191 is a Class B 192 to 223 is a Class C

if you can remember those ranges I would

commit them to Memory you'll be good to

go for the exam now within each of these

classes there are a number of addresses

that are not allowed to be assigned or

leased for specific reasons these are

what we call reserved and restricted IP

addresses now we've mentioned the

127.0.0.1 or the local loopback or the

localhost i p address before which can't

be assigned because it's reserved for me

for myself from for I this means that

this address is used when I want to

address myself

so if I wanted to for instance assign

myself my own name via DNS and my name

was me

me would link up to the IP address

127.0.0.1 and that way it's going back

to myself now we're really going to use

this for mostly diagnostic purposes if I

want to double check to make sure for

instance that tcpip is running correctly

and it's also going to be used for

programmers and such like that now the

address

10.0.0.0 is also restricted and it's not

available to use because again this a

host address can never have all zeros

conversely the addresses that have all

ones for instance

255.255.255.255 cannot be used for

um uh addresses obviously this one can't

because it would sort of

ruin the use of a subnet mask but even

if I had something like

192.168.0.255 I can't use that because

that's what's called a broadcast address

and so it's just simply reserved for

that this means that if a message is

transmitted to a network address with

all ones in the host portion or 255 that

message is going to be transmitted to

every single device on the subnet it's

called a broadcast and we talked about

broadcast before finally the address

1.1.1.1 cannot be used because this is

what's called the all hosts or the who

is address so these basically what

whereas 127 is for me

1.1.1.1 is for everyone so these we can

never use the important one I really

want you to remember here is this one

and you're going to want to remember

that for instance 255 in the host

portion can never be used again not only

because that's going to ruin a subnet as

we've talked about but also this is

reserved for what's called a broadcast

address now there are portions of each

class that are allocated either for

public or private use private IP

addresses are not routable

this means

that they are assigned for use on

internal networks such as your home

network or your office Network when

these addresses transmit data and it

reaches a router the router is not going

to uh route it outside of the network so

these addresses can be used without

needing to purchase or leasing an IP

address from your ISP or Internet

service provider or governing entity so

this is how I could create an internal

Network in my home and I don't need to

go register it and I might not be able

to access the internet but I don't need

to register if I want to go out to the

internet then I can share using devices

and resources we've talked about

previously and we'll talk about later a

public IP address with all the internal

devices that are configured using

private IP addresses now since these are

not able to be used externally to our

Network these IP addresses can be used

by as many devices as necessary as long

as we never double over one IP address

per device so the class a private IP

address range remember we talked about

10.0.0.0 because we cannot have zeros

right remember 10.0.0 and 285 we

actually cannot assign but any address

in between that so

10.1.126.5 would fall into what's called

a private address range and you might

see this in your home router as well so

this makes it easily discernible from

other addresses in its class anything

that has the 10 to begin with cannot be

used on a Class A Network or any network

except privately

we also have a class B uh Private

Exchange which is

172.16.0.0 through

172.31.255.255 and Class C which is

192.168.0.0 through the 255 to 255. this

one you might have seen the most this

one I'm guessing you've seen the last

this one's probably the second most

common the 10 dot so if you have a

internal Network at your home you might

have your address on your computer right

now for instance if it's not connected

directly to the network if it's

connected to a router might be something

like this or like

this or even

like this all right that's because these

are each private addresses it's

important that you commit these to

memory as well because these will appear

on the exam and remember the important

thing with a uh

with a private IP address as I mentioned

right here is they're not routable and I

don't need a lease to use them so when

tasked with subnetting a network you

need to understand how to calculate how

many hosts and how many networks are

available if we want to determine the

number of hosts that are available we

apply this Formula 2 to the x minus 2.

and this is where X

equals the number of node bits and

that's after we break it down from

decimal to binary

now the reason for the minus 2 here

is because again we cannot use a DOT

0.0.0 address or

a.255.255.255 address which would mean

all zeros are all ones in the subnet and

so we need to make sure uh rather in the

um uh in the bit right when it's broken

down and so we need to make sure that

um this is the case

we also need to know the number of

networks and to do that we're going to

do 2 to the Y minus 2 where y equals the

number of network bits so let's take a

look at this if we have the IP address

162.85.120.27 and we have a subnet mask

of

255.255.255.0 by the way

we can look at this and we automatically

know that

162.85.120.27 this looks like a class

b i p address and the 255 the 255 to 255

is actually our default Class C subnet

so this is not the default that we're

working with here so we need to figure

out uh some information here so let's

break it down into bits and I'm do that

here and if you wanted to check my math

you could now the number of network bits

is right here the Y and the number of

node bits is right here

the X so if we pop this into our

equation the number of possible hosts we

have is 254 and the number of possible

networks is over 16 million if we go

back to that table we saw a few slides

ago we'd see then that that's why we

have a default for class B and Class C

networks is we can see how many networks

are possible and how many hosts are

possible now why would I want to know

this well let's say that I have to

divide up my network and I want to have

a certain number of networks in a

certain number of hosts well if I only

need five networks but I need 30 000

hosts I'm going to be in major trouble

here because now I have to divide this

up so much I'm wasting a lot of networks

and I don't have enough hosts so we want

to determine how we can do this to

reduce the amount of waste we're going

to talk about that in just a bit

going back to something called a default

gateway for a second

device that wants to connect to the

internet has to go through what's called

a default gateway this is not a physical

device this is set by our IP address

settings it is basically the IP address

of the device which is usually the

router or the Border router that's

connected directly to the to the

internet for instance we had other

routers in here

this is going to be the Gateway

and so three things need to be

configured on any device that wants to

connect to the internet we've talked

about it we need to have an IP address a

subnet mask and this is the new one a

default gateway so this is the device

that's used when I want to communicate

with the internet and it's not used when

communicating with devices on the same

subnet this is why it's called a Gateway

think about it as your gateway out to

the network most often and more often

than not as I mentioned this is going to

be the router so if you have at home for

instance a router that's

192.168.0.1 that is also your default

gateway and if you went and did an

ipconfig all something we'll take a look

at later and command prompt you'd be

able to see then your default gateway is

this address basically it means hey I

don't know I want to get up to the

internet I don't know how to get to

Google I'm going to ask my default

gateway the default gateway then takes

care of everything else and then the

information comes back and it sends it

out to you again now there are a couple

different ways of implementing custom IP

addresses we previously described how we

could use custom subnets and with that

method a custom subnet mask and an IP

address is what we call anded if you

recall and together they allow the node

to see the local network as part of its

larger Network now each customized

subnet is configured with its own

default gateway allowing the subnets to

be able to communicate with each other

now another method of doing this is

called vlsm or variable

length

subnet

mask

and by using this we're going to assign

each subnet its own separate customized

subnet mask that varies

now the VLS MF it allows for a more

efficient allocation of IP addresses

with minimal address waste which I was

just talking about so for example let's

take a situation in which a network

administrator wants to have three

networks and I have a class

c space

now just so you know some of this is

very outdated and we're not going to see

it used a lot of the time that being

said Network plus really wants you to

know about it so we're going to cover it

so I know I need to have three different

networks or sub Networks and I know on

the first Network I want to have four

hosts on the set network I want to have

11 hosts and on the third network I want

to have 27 hosts now in order to

accomplish this I could use the subnet

mask

255.255 the 255.20 that 224.

and for each of these subnets if I was

to add this out right one two three four

five six seven eight that's 255 one two

three four five six seven eight

that's 255 one two three four five six

seven eight that's 255 let's write 224

in bits all right let's go through our

calculation again here I'm just going to

do this because it never hurts

to do this a couple times

so let's write all of these out

great all right we have one two four

eight sixteen

32 64 128.

now we remember that subnet masks have

to have continuous ones so that's 128

128 plus 64 is

192 plus 32

is 224.

so then if we broke this down into bits

this is what it's going to look like

okay

so let's write that out here

and if we do our calculation we know we

need to have how many hosts when we need

four so let's do our calculation 2 to

the 1 2 3 4 5 power

right

we're going to figure out how many hosts

that equals we already know it's 32.

minus 2 means that we can have

up to 30 hosts on this subnet

so I'm wasting an effect 26 addresses on

this subnet 19 on this one and three on

this one I'm not really doing a good job

because I've had to apply the same

subnet mask

to every single

IP address

and in doing so I'm wasting a lot of my

possible addresses

now if I used vlsm instead it's going to

erase all this

I could do

255.255.248.240 and.224. now remember uh

248

if we route that out

I'm just gonna

really quickly

all right and you can double check my

math here

if we do 248

that is going to be

one one one one one one

zero zero zero

all right and then if we do our

calculation two to the 3 because we have

three host bits

what does that equal eight minus two

well now

we have a possibility of six hosts so

what is our waste two because six minus

four equals two a lot better right if we

do the same thing with uh the next one

and you were to do the same thing I just

did that would look one one one one zero

zero zero zero we did the calculation

again two to the four because now we

have four bits

minus two

which equals 16 minus two which equals

fourteen so now I'm only wasting three

bits because 16

sorry 14 minus 11 equals three and

finally 224 is the same remember that

was 30 bits or 30 hosts rather 30 minus

27 is 3. so doing this variable

we are a variable subnet mask we're no

longer wasting as many host addresses so

by utilizing this we're going to

appropriately plan and Implement a

scheme and it allows us to use our space

much more effectively of course the

negative aspect of this is it's a lot

more harder to scale

and if I want to add nodes to these

customized networks I might have to go

around and change all the subnet masks

as well now cider which is cidr which

stands for class less

enter

domain

routing

is also commonly called super netting

or classless routing it's another method

of addressing that uses the vlsm but in

a different way is at the 32-bit word so

the notation is much easier to read

because it combines the IP address

with this Dash after it

for instance the number is what denotes

the amount of ones in the subnet mask

from left to right so if we look at this

notation right here we have

192.168.13.0.23 well the 23 means there

are 23 ones from left to right in the

subnet mask

okay and now if we were to convert that

this allows for a possible amount of

host addresses 2 to the ninth

minus two

which equals 500

and 10 addresses so this allows for more

than one class full Network to be

represented by a single set basically we

can now break it up further into smaller

sub networks if we look at three of the

most easily recognizable ones I'm just

going to erase this so we can get a

better look here uh the slash eight

the slash 16 and the slash 24

we can see that these translate

basically over to the basic Class A

Class B and Class C networks right

because slash eight Class A that means

it's one one or one two three four five

six seven eight dot zero dot zero dot

zero which would mean

255.25.0.0.0 which is our default subnet

mask for Class A

because again

this is my network ID is the first octet

and the node ID are the last ones and

you can see that that would fall out for

the next ones as well so because of the

ease by which it is we can subnet

networks this way because of readability

and efficiency cider notation has become

extremely popular and wider widely

adopted

most of the internet in fact has become

class less address space because of this

meaning that we don't really use classes

and we get to IPv6 we're not going to

see it at all now again this is very

complex the important thing I just want

you to remember on this whole thing is

that if you see this Dash after

an address here you know exactly what

the subnet mask is and then you can

backwards engineer or forward engineer

the IP address or the network ID or node

ID

so just to review some of the points

that we covered here we started by

outlining the ipv4 addressing scheme we

looked at the five classes the three I

really want you to be aware of are a b

and c remember a is anything in the

first octet that's one

through 127

with class B we're looking at anything

from 128

to 191 and with class C we're looking at

anything from 191 or rather 192.

to 223. anything else here we're really

looking at experimental and stuff that

we don't really need remember these

ranges for that first octet it's easy

then to determine what class we're

looking at

okay so we also described the reserved

or restricted IP addresses for instance

we can't have anything

with a zot 0.0.0 or

with a 255.255.255.

because these are a multicast addresses

and we also can't have anything with

127.0.0.1 ever

or

1.1.1.1 because these are both ones the

localhost one is the who is address

we then looked at uh private IP

addresses remember we had three

different ones each for each class for

class A it was anything 10.x.x.x

with class B it was one seven two dot

sixteen dot x dot X through

172.31.x.x and the one you're probably

most familiar with is the class C which

is 192.168.x.x

remember that you can see what class

they're in

by looking at this and most importantly

class a private IP address can allow for

the most networks the fewest I'm sorry

the most nodes the fewest networks Class

C is going to be the complete opposite

I'm going to allow for the most nodes

the most networks rather but the fewest

nodes okay and again remember these

ranges because they will come up what is

make a private IP address it is not

routed past a router onto the public

network okay we also talked about the

ipv4 formulas which allow us to

determine

how many hosts

or how many networks are allowed on a

network and that is where the x or the y

equals the number of hosts or network

bits we defined the default gateway

which is what I need

to get out to the WAN it's what a local

device a node on the local area network

needs to go to this default gateway and

finally we Define the two custom IP

address schemes the one which allows me

for variable subnetting and the other

cider which allows me to

use a slash and then put a number that

number representing

the number of

Network bits in the subnet mask

right so the most popular of course 24

would be for a class C

16b for a class B and 8 would be for a

class A because if we had a slash eight

that would mean the subnet mask is

255.0.0.0

[Music]

foreign

Network routing and IP addressing

data delivery techniques and IPv6

now we've talked a lot about IP

addressing when it comes to ipv4 or the

Internet Protocol version 4 but fairly

recently IPv6 or IP or Internet Protocol

version 6 was released and has now begun

to be implemented across the world in

every Network situation so in this

module we're going to discuss the Core

Concepts that are involved with IPv6

addressing and some of the data delivery

techniques as well so at the completion

of this module we're going to have a

complete understanding of the properties

of IP version 6 or IPv6

and we're going to be able to

differentiate between IPv6 and ipv4

which is the one we've been talking

about up into this point as a reminder

ipv4 is that IP address that is 38-bit

32 bits and divided into four octets

and we're also going to outline some of

the improvements in the mechanisms of

IPv6 and why we needed to have another

version of Ip addressing

we're also going to cover the different

data delivery techniques as well as what

a connection is different connection

modes and we touched on these briefly

such as connection oriented and

connection less and they're transmit

types finally we're going to go further

into data flow or flow control which

we've talked about a bit and we've

mentioned a bit buffering and data

Windows these are all techniques that

allow data to be sent over a network in

varying ways and finally also we're

going to talk about error detection

methods that way we know when data

arrives on the other end we can double

check it to make sure it is the data

that was in fact sent

so in the last module we learned about

the ipv4 addressing scheme and we talked

about some aspects of How It's

implemented now IPv6 is the successor to

ibv4 and it offers a lot of benefits

over its predecessor

the first major Improvement that came

with this new version is that there's

been an exponential increase in the

number of possible addresses that are

available

several other features were added to

this addressing scheme as well such as

security

improved composition for what are called

unicast addresses header simplification

and how they're sent and a hierarchical

addressing for what some would suggest

is easier routing and there's also a

support for what we call time sensitive

traffic or traffic that needs to be

received in a certain amount of time

such as voice over IP and gaming and

we're going to look at all this shortly

so the IPv6 addressing scheme uses a 128

bit binary address this is different of

course from ipv4 which again uses a

32-bit address so this means therefore

that there are two

to 128 power possible addresses as

opposed to 2 to the 32 power with um IP

address 4.

and this means therefore that there are

around

340

undecilion I'm going to write that out

so that's a word that you probably

haven't seen a lot on

decillion addresses and to put that

another way it's enough for one trillion

people to each have a trillion addresses

or for an IP address for every single

grain of sand on the earth times a

trillion Earths give or take a bit so if

the 128-bit address were written out in

binary it would be

128 ones and zeros because that is

binary

and even in decimal form that's a pretty

hard to read and keep track of so

because of this we use what's called

hexadecimal

as the format in which uh IPv6 is

written and if you imagine from the name

hex uh binary is a base 2 system meaning

that we take everything to the power of

two so we have the ones place and then

we have the two place and then we have

the fourth place and so on and so forth

with decimal which is a base 10 system

we have the ones place the tens place

the hundreds place which is ten times

ten the thousands place and so on with

hexadecimal though

we're looking at a base 16.

so every single digit

has a possible 16 different options so

we'd have a ones place which we always

start with a ones place and then a 16s

place and then so on and so forth now

the way we do this is that every digit

as opposed to decimal where we have zero

to nine options for every digit and

binary where you have either zero or one

with hexadecimal we can either have zero

to nine

or a through F if we add this up we have

10 options here 0 through 9 and then a

through F we have six so a hexadecimal

number is going to be a combination of

anywhere from 0 to f

uh a would be 10 B would be 11 C would

be 12 and so on and so forth so when you

see uh this written out that's what that

means okay now the address is broken up

into eight groups of four hexadecimal

digits

and these are separated by colons

now uh I'm going to show you this in

just a second but there are also a

couple of rules when it applies to when

we come to readability

so the first rule

is that let's say this is our

hexadecimal

IPv6 address you notice first of all one

two

three

four

five

six

seven

eight right there are eight groups

of four hexadecimal digits each

and of course each one of these digits

has 16 possible values okay so let's

look at two rules and these are also not

only readability rules but what we call

truncation rules meaning this is how we

can shorten

an IPv6 address since they can get quite

long

the first rule is that any leading zeros

can be removed so if we imagine any

leading zeros I'm going to circle them

right there

right here

right here and if we wanted we could

even consider these leading zeros

and therefore if we rewrite this out

below you'll see we're going to remove

all the leading zeros

and that allows us to shorten

our address

now we could also

if I was just going to take this one

step further

I could also shorten

these zeros if I so wished

and just leave one zero there

now no matter how you write out

the address the rules are put in place

in a way that you can always go back to

the

main address and so you don't have to

worry about you know you can sort of

pick and choose there are best practices

but the computer is always going to be

able to figure it out okay

now the second rule is that successive

zeros or successive sets of zeros can be

removed but they can only be removed

once so any sets of successive zeros and

here we see

one set or two sets rather successive

zeros can be removed and replaced

with a double colon

now the reason we can only apply that

once is let's say these zeros

were we had another set of zeros over

here and we

um

truncated those

we can add up right we know there's one

two three four five six sets here so we

know that this represents two sets

of missing zeros but for instance if we

had you know two other sets

here and we remove those we might not

know

whether it's supposed to be one set and

three sets or two sets and two sets and

so on and so forth so we can only do

this once because when we add them back

there's no way to know

um

uh you know where that would sort of lie

now uh I'm just gonna erase this for a

second because we can even truncate this

more we've applied this rule

so this applies this rule this one is

applied this rule but we can apply both

rules right so we can remove these

leading zeros here and actually write

this out

as 2001

d8

eight eight a three double colon which

means that those are successive zeros

three e seven zero seven three three

four

now let's just I just want to uh sort of

follow up and explain write out what I

was just talking about with why we can't

have more than two sets of successive

zeros okay let's say that we have zeros

here as well

okay so I'm gonna rewrite this out we

have zero zero zero zero colon zero zero

zero zero colon zero eight

A3 colon zero zero zero zero zero zero

zero zero

eight c three e zero zero seven zero

seven three three four okay

let's first apply our first rule which

is that leading zeros can be removed so

we rewrite this and we're going to get

this

okay now we're allowed to remove one set

of leading of successive zeros only

which is the second rule okay but let's

do it twice and just see what happens so

let's say we have a double colon here

8a3 and then we have another double

colon

8c3e

seven zero

seven three three four now

let's say we want to expand this back

out to its full version

well if we have the successive zeros

here

we don't know if this would be written

out zero zero zero zero

dot 883

because from what we're seeing here

theoretically we could put three zeros

here and one zero here right or we could

do it the other way around so the reason

we can only do it once is because then

mathematically we know exactly

how many belong when we do that all

right so hopefully that helps clarify

the reason behind the success of zeros

being removed

all right now uh what this also means is

that if you remember a loopback address

an ipv4

the loopback was

127.0.0.1 while we also have a loop back

when it comes to IPv6

that's all these zeros to one but

because we can apply all of these rules

we can truncate this to Simply this

all right

so uh this is important to remember

these rules are important to remember

the other thing I want you to remember

is that hexadecimal

zero to nine a to f so they might show

you something and say which of these is

not a valid IP

if it has a letter say G or an H then

you know it's not going to be valid and

here we can check here's a d That's good

here's an a that's good C good

e good so this is good to go right if we

had an H or a g or an X for instance

then we would know that the um IPv6 was

incorrect because there's no hexadecimal

symbol X

so the ipv4 addressing method is is

really different from IPv6 addressing

and it's comparatively it's lacking in

many areas first as we've talked about

we're using a 32-bit binary address in

ipv4 versus a

128-bit binary address in IPv6 and of

course this greatly increases the number

of possible IP addresses I think around

February of 2011 all of these IP

addresses had been leased and uh so

there weren't any addresses left I think

we had something right like 4.8 0.7

billion right and all those were gone

and so we were depleted of all of our IP

addresses

so this is why we had to transition to

IPv6 because now we have that

undecillion uh address which again is if

every there were a trillion people they

could each have a trillion addresses now

another major difference between these

two is that uh ipv4

utilized the classless inter-domain

routing notation if you remember which

had that slash and then a number of bits

well

in IPv6 this isn't necessary and IPv6

actually has a subnet size of 2 to the

64 power now if you remember

that the total IPv6 is 2 to the 128 then

what you realize is that the first half

of the IPv6 address so if we were to

write one out again let's say 2 0 8 a

3 6 4.

uh nine two B

f

one zero zero zero right okay so then

we're gonna have four more on this side

the first four

which again is the first 64 bits that's

the subnet

so now we've integrated the subnet into

the IPv6 address which is the benefit

now we don't have to sort of have this

extra

uh uh written out cidr thing so it's

been standardized it's always 2 to the

64. we always know the subnet or the

network node is on the first

section and the node ID is on the

section the second section the other two

to the 64. so this really help helps us

simplify things to a great extent now

obviously one of the issues is we're

going to under use a lot of the

addresses we're going to under use many

of our addresses because we're never

going to have to really use this many

subnets or perhaps not even that many

networks right but um there are so many

other benefits that it has with routing

and efficiency and simplified management

that it it sort of

um makes up for it and so that's why

we're going to make that sacrifice now

in terms of domain name systems uh with

DNS when we talked about for instance a

google.com

going over to say you know whatever that

IP address is

I'm making this one up obviously it's

not a real one because we're in a

private IP

but this was called an a record right so

a server would have something or a DNS

server would have something called an a

record and that a record had this

information in it

all right now when we're dealing with

IPv6 we're utilizing

a quad a record for this mapping now we

can also use the same a record but this

quad a record can be used as well so if

you see Four A's what we call a 4A

record or a quad a record then you know

we're using IPv6 it's one of the

differences and again these are the

records that are used to map IP

addresses to what are called fully

qualified domain names

now while comparing these two schemes

also

ipsec which stands for IP

security is another aspect that we need

to consider in ipv4 ipsec is optional

it's widely used for secure traffic over

ipv4 Communications but when we dealt

with

IPv6 ipsec was designed for it and so uh

it's required from the original

specification and therefore all

Communications that are working over

IPv6 are automatically falling under

ipsec so it can be considered in some

ways optional I guess but it is required

use from the get-go because it was built

into IPv6 now the IPv6 scheme can also

handle a much larger packet size the

packet size for ipv4 is 65 535 octets

payload when we get to IPv6 we're

dealing with a

4.295 billion octets of payload so

obviously these are a lot bigger these

are what we call

jumbo grams

as a result you can imagine that if we

want to deal with ipv4 and we're on an

IPv6 Network we're going to have to make

up for this now if you recall we were

talking about ethernet we also were

talking about the header sizes and all

the information that was contained in

there well the header size for ipv4 and

IPv6 is also very different which

actually makes these two

protocols not compatible with each other

so IPv6 is not compatible with ipv4

and so the way we're going to

communicate with an IPv6

over an ipv4 network if we need to is by

tunneling

the packets in other words we take an

ipv4 packet I mean an IPv6 packet and we

literally wrap

it around

where we wrap around it in ipv4 packet

and so we tunnel the IPv6 packet inside

of the ipv4 now this allows it to

communicate but this is also what we

call a dual

foreign

in some cases we can have what's called

a dual stack where we have an ipv4 and

an IPv6 and so we can choose which one

to go over and then this tunneling is

not going to be necessary now

we don't really want a tunnel because

obviously the payloads are so much

different in size that it's going to

cause all sorts of trouble so what we'll

try to do is create this dual stack in

which we have one network and the other

and they're both operating sort of side

by side if we can't do that then we have

to use tunneling in order to move the

IPv6 data over an ipv4 Network which

might be necessary even if the IPv6 data

is traveling through an ipv4 Network

all right so we've compared these let's

talk about some of the improvements that

ipv4 did not have that IPv6 does uh

starting with some security and privacy

measures if privacy extensions are

enabled with IPv6 then we have something

called an ephemeral address which is

created

and this is used as a temporary and

random address that's used to

communicate with external devices but

the external device doesn't know the

true address of the internal device and

so this improves the the privacy and

security for the user and this is what

we call a privacy extension and it does

have to be enabled

some sort of a router point of view now

another Improvement is a better

composition of what we call the unicast

address what this means is that IPv6

uses a unicast addressing structure to

replace the classful addresses of ipv4

this offers a lot more flexibility and

efficiency with addressing and depending

on the category of the unicast address

used there are different functions for

each meaning that there are different

types of addresses that are used and

that way the computer automatically

knows what the function is the first is

called a global address which is sort of

like the public or routable addresses uh

in ipv4 if you recall most addresses

could be routed those are what we call

Global addresses

we also have site local addresses which

are essentially like the private

addresses or non-routable addresses that

are not routable to external networks if

you recall

these were for instance the

10.0.0.0 through

10.255.255 at 255 and then the

172.16-32 and then the 192.168 those are

the private addresses well in IPv6 we

call them site local addresses we also

have something called link local

addresses which are basically comparable

to a pipa addresses in ipv4 and we're

going to talk more about what those mean

in just a little bit later but just to

give you a little heads up and we have

talked about it with uh uh a plus if you

around for that this is automatic

private

IP addressing and we need because every

device needs an automatic IP address if

it's not given one by a server then it's

going to give itself one what we call an

apipa address and so in IPv6 these are

called link local addresses

finally there are IPv6 transitional

addresses which are basically going to

be used in the time being until we phase

out of ipv4 these are used to Route IPv6

traffic across ipv4 networks through

tunneling much like I've just described

in the previous section

now a mechanism uh built into IPv6

addresses is a field located in the IP

header

that's designed to guarantee network

resources be allowed allocated to

services that need time sensitive data

such as voice over IP right we need that

that is time sensitive because I'm

talking and I want the person to hear

almost as soon as I talk and so this

time sensitive stuff is built into IPv6

one of the reasons that we use it now

another improvement with this scheme

IPv6 is called hierarchical addressing

this eliminates the random allocation of

addresses so connectivity devices such

as top level routers are assigned a top

level block of ivv6 addresses and then

segments are added to those with blocks

of addresses that are assigned at that

level so basically it looks like a

hierarchy

from an IPv6 standpoint

you remember we looked at an uh this

sort of topology earlier

now ibv6 scheme also has a much

simplified header and it's going to make

addressing a lot easier to read

this improves the speed packet routing

on an individual packet basis so

obviously if we can

simplify how information can get read

it's going to simplify how routing can

occur

now data in transit is susceptible to a

variety of things that could cause it to

be delayed lost or damaged and these

things can occur on the transmit side

and quite commonly on the receiving side

as well so the method the data is

delivered makes a huge difference in

whether the data is going to arrive at

the destination correctively

and efficiently

so depending on the method of delivery

there can be error detection which would

mean we detect that there are errors and

error correction which means we not only

detect but we fix the errors when these

recovery mechanisms are used now an

important aspect of the data delivery

begins with the actual connection itself

so depending on the type of connection

service used is going to give us an idea

of what sort of delivery options are

available

so a connection in terms of networks is

The Logical joining of two network

devices through a specified medium that

is established and maintained for a

period of time during which the session

exists in other words the connection is

what allows data to be transferred

between say my computer and a server

computer

now in networking and specifically in IP

networks there will be connection

services that attempt to provide data

integrity and reliability now there are

generally three types of connection

services that we see when we discuss

certain protocols and we've talked about

these in some way shape or form but it

doesn't hurt to sort of go over them in

a little more specific detail

first is an acknowledged connectionless

service in these the connection isn't

created

however when data is received by the

destination there is a acknowledgment of

a receipt so website Communications use

this type of service a great metaphor to

think about this would be for instance a

delivery receipt

with regular mail

so it's not certified we're not going to

get a signature but what we do is we get

a receipt that it has been delivered now

with unacknowledged connectionless

Services there's no acknowledgment sent

unless the application itself does this

this could also be considered Simplex

Communications which we'll talk about in

just a second so this is just like

regular

mail

we send it we drop in the mail there is

no acknowledgment okay acknowledged at

least has

uh and acknowledge that data has been

sent but there is no connection made

right there is no established session

made between the receiver and the sender

finally we have connection oriented

services and by the way when we talked

about these connection lesses we recall

this is like UDP which is connectionless

and IP

here connection oriented we're looking

at TCP

now these are where error detection and

correction are available as well as some

flow controller packet sequencing in

other words this would be like certified

mail

now there are also three types of

connection modes that we're typically

going to use they're Simplex half duplex

and full duplex

with Simplex this is one way

communication only this is sort of

similar to FM radio broadcast

right you turn on your radio you tune in

and you can receive but you cannot send

data

now we also have half duplex this is

two-way communication but only one at a

time this is like a pair of regular

walkie-talkies only one device can

transmit at any one time which is why we

have to use those code words right over

over over and out so this is like a

walkie-talkie finally we have full

duplex which is two-way and both ways

simultaneously this is similar to the

telephone in which we can talk and

listen at the same time in some ways we

have trouble understanding each other as

a result of it now in networking devices

are designed to receive and transmit

data at different speeds and with

different sizes of packets as well so

certain devices are not going to be able

to handle as much data as others at one

point or another we talked about this

briefly with mtus and MTU black holes so

flow control is the managing of amounts

of data and the rate at which the data

is being transmitted emitted over a

network connection

flow control is necessary to help

prevent devices from being overflowed

with data some devices when there's too

much data is received are going to

potentially shut down to prevent certain

attacks or simply are going to drop

packets that are too large because

they're going to cause delays on the

other side of the scale if too little

data is being received by the device it

may just be sitting idly by waiting for

the remaining packets in this case it's

simply a matter of efficiency so there

are two main types of flow control that

are covered on the exam buffering and

data windows

buffering is a flow control technique

where a portion of the memory either

physical or logical via software is used

to temporarily store data as it's being

received in order to regulate the amount

of data that's being processed buffering

may be used to maintain data consistency

as well as minimize overloading now Ram

uses a type of buffer when data is being

read from its cache right so remember we

talked about RAM and that was what we

called Cash

now with buff bring there is a potential

concern because what if the buffer

becomes full well when receiving nodes

buffer reaches a certain capacity it

actually transmits a squelch signal I'm

going to write that out just not only

because it's a great word

that says stops transmission or slow

down your transmission so I can catch up

now a commonplace we're going to see

this type of flow controls when we're

streaming movies you might have seen

buffering when you're using movies for

instance on YouTube

or on Netflix or any of these sites the

idea is if there's a problem with our

communication

we have a little buffer of data so that

way we're not going to see a dip in

quality of the film

now another type of flow control is

called Data windows the data window

refers to the amount of data being sent

and it can either be a fixed amount or

it can vary and these are fixed length

windows or sliding very sliding Windows

rather if you think about the window

and I put the data inside of it

we can either have a window that is a

specific length like this

or

a window that can't possibly

get smaller based on the data

and that's what fixed length and sliding

windows are so to go a little more in

depth into these with fixed length

Windows the size of the packet of the

data being sent is determined by

the sender and the rate of transmission

is determined by the receiver so the

size is typically going to be pretty

small and overall this is going to be

fairly efficient the other thing to

remember is that the packet size is

always going to remain the same it's

never going to change so if I need to

send

10 packets they're all going to be

exactly the same size or as much as I

can draw them as such

and so on and so forth now with a

sliding window method it's a bit

different the sender begins to transmit

data typically with a small number of

packets and with each transmission

it uh waits for an acknowledgment or act

packet receipt now with each receipt

this contains the current maximum

threshold that can be reached and then

the transmitter is going to begin

increasing the number of packets by a

specified amount in other words it's

going to start sliding that window from

here

over

now it's going to continue to increase

this over and over and over

until we reach a maximum potential

at this point we're going to start

getting some congestion and so the

receiver is going to send another act

saying listen you need to slow down now

and and this is a good rate

this method is really going to allow for

minimal data traffic congestion and a

lot of throughput

depending on the amount of traffic the

size of the window can really vary

dramatically and so this really gives us

a lot more flexibility if you imagine if

I have a home that has a whole bunch of

irregular Windows I'm going to want

sliding Windows now if I have a home

with all these similar Windows

everything built the same then I can use

a fixed link window but this one's going

to give me a lot more flexibility

now error detection and correction is an

important aspect of how we know our

information arrives at the destination

unhindered and unaltered one method

achieves this by attaching supplemental

information at the end of the footer

that pertains to its contents and the

receiving station is going to look at

that data and compare it to the data it

received

the data matches it's going to consider

it error free if not the data is going

to be requested to be re-transmitted now

when an additional Correctional

component is added that allows the data

to be rebuilt in the error in the event

of an error this is going to become an

edac or error detection and correction

now parity check is a process where an

extra bit is added to every word of data

the receiving station can look for the

bit on this word by word basis remember

we're talking about words we're not

talking about uh language we're talking

about words as far as data goes and so

it can look at these and therefore it

can determine any errors that are built

in because parity adds this extra bit to

every word this method takes a little

bit of overhead so it does ADD

not only extra resources but some more

data in there now with something called

CRC or cyclic redundancy check a code is

added to every block of data through a

mathematical operation

which is also referred to as hashing

now this code is added to the end of the

block and then it's transmitted

when the receiving station applies this

hashing method this mathematical

operation to the code

then it can should get the same data and

if it doesn't then it knows there's a

problem and it can request it to be

resent like parity CRC is also going to

add a certain amount of overhead because

it takes data and calculation time all

right so now just to review some of the

topics we talked about we talked about

the IPv6 addressing scheme specifically

we talked to that it's a hexadecimal

128 bits

divided into

eight sections

we also compared and contrasted IPv6

with ipv4 we saw that IPv6 for instance

has ipsec built in

and has a whole bunch of other

improvements and mechanisms such as data

delivery time sensitive and so on and so

forth the important thing I really want

you to know about IPv6

is that it does not require

a subnet

and we need to recall all of the

truncation or readability rules

which include removing leading zeros

and

combining successive

sets of zeros

but only once

we also explained the different data

delivery techniques and we defined a

connection the different connection

modes whether they're acknowledged

connectionless

simply unacknowledged connectionless

or connection oriented

we also looked at the different transmit

types including Simplex which is one way

half duplex which is like our

walkie-talkie

and full duplex

which in effect doubles our bandwidth

we also explained flow control buffering

and data windows we use buffering a lot

when we're talking about videos in data

Windows remember we talked about the

fixed

and sliding windows

finally we outlined error detection

methods including parity which adds an

extra bit to every word

and

CRC or cyclical redundancy check which

uses hashing a mathematical operation so

that we can ensure the data that was

received was also the data that was sent

[Music]

welcome to module 6 lesson 4A IPv6

Concepts

now we actually covered IPv6 earlier

however as per usual some new ideas have

been added to the syllabus so what I'll

do here is I'll review some areas that

you've already covered with Josh

with my own take and then we'll go into

the new stuff

so IPv6 addressing address types

new is a neighbor Discovery protocol

which is part of IPv6 built in

the eui 64 addressing is new

tunneling types is new

so ipv4 which is obviously the precursor

to IPv6 it created a long time before we

had home computers computers were pretty

expensive and big probably the size of

any room in your house

so no

um nobody foresaw that people would be

using

uh home computers just like when the

telephone was created I think uh one of

the first comments was why would I I

don't need to phone anyone

so uh there we go

uh so it was just the scheme was

designed just to cater for commercial

Enterprises only so we didn't think we

were going to run out

lack of a simple Auto configuration

mechanism so I eventually we had

um DHCP was uh created

which works well obviously it's got some

drawbacks

an ipv4 has no security built in again

nobody realized that

well there was no such thing as hackers

obviously when IP was brought out

because they hadn't been invented yet so

nobody thought that we needed to have it

built in

ipv4 is hard to use with mobile devices

especially when we're using the cellular

Networks

ipv4 needs massive writing tables

required over the internet internet

service providers have huge tables for

routing all the IP traffic

uh there's only around four million

addresses available we actually ran out

of ip4 addresses some time ago and

around 50 of the traffic going over the

internet at the moment is IPv6 which is

why yeah we need to know about it

so IPv6 uh there's that many addresses I

don't even know what the numbering

system is called for calling out that

many but for every person alive there's

many millions of available addresses now

and that can be used with IPv6 and

you'll read some documents about an app

PT not really used and there's no need

two and not because there's just no

shortage of addresses really security is

built into one of the fields in the IPv6

packet

we have addressed Auto configuration

which um is a major part of IPv6

and it's plug and play as well so things

like when you enable IPv6 on an

interface with most devices now it

actually self-configures an IPv6 address

we do not have broadcast and IPv6 we'll

come to that later

uh it's built to work plug and play with

mobile devices again which is Handy

so the address is there's several rfcs

one of the main ones is 1884 if you want

to read it it's a 128 bits each of these

bits is divided into into eight groups

of 16 bits and then each of those bits

is separated by a colon which is a DOT

on top of a dart

HEX number it is used because it's just

a lot easier to write out that many bits

using hex and it is in um binary it

would take forever

the address is when you're typing them

out on interfaces is not case sensitive

so you could use caps lock or lowercase

and the address will work fine and be

accepted

here is an example of an IPv6 and you

can see

if we just come over here

so eight groups of 16 bits which you'll

go into into a minute uh divided here by

the colon and another 16 bit 16 16 16 16

and so on

so if you wrote the address out in

binary just for the

I don't know why I should have said D

here sorry Eed e e d e

but if you change the hexadecimal here

so this is the hex

into the binary value it's one in the uh

if I go one

to I know you already know how um binary

works for eight so one in the eight

column one in the four one in the two so

eight plus four

uh it's twelve eight nine ten eleven

twelve thirteen at fourteen so the E is

number fourteen

here uh 14 here in HEX

now we've got the D so we've got uh one

plus four plus eight so eight nine ten

eleven twelve

thirteen so D is 13.

and then we're back to another 14. 16

bits two bytes in total so four bits

uh four bits eight and then another

eight 16 bits so that's two bytes

we can compress the address

so you can remove the leading zeros

leading zeros are numbers that appear

before and so this is a leading zero

leading zero this is a trailing zero so

we can't remove these because they've

got numbers uh prior just before so if

we get rid of the leading zeros for

example here zero zero zero one becomes

a one

zero seven eight nine becomes seven

eight nine and this is uh to save space

and for when we're writing out the

address is zero ABC becomes ABC and you

can get rid of the trailing zeros here

and just have one zero so this address

is uh legal

to write that out you could possibly

have questions in the exam uh asking you

to choose the correct compressed address

you can use a double colon

wants to represent consecutive zeros so

here we go we've got all these

consecutive zeros here for some reason

well we've got rid of them just by

having the double curl on here

and we've got a double coal on here

between the one two three four

so what we've done is just compress all

of these zeros and we've done it again

here

and then just to we could have put it in

the second set of zeros but just to save

space we've got rid of all these zeros

here

so practice this work out your own

numbers because this is a typical exam

type question

main

IPv6 address types Global unicast unique

local link local and multicast you'll

note we don't have broadcast that isn't

a legal address and we also have any

cast which I'm not sure if I mentioned

here

so the global unicast the this is

allocated by the ISP and then you will

get a mask Associated whatever the mask

may be

these are routable on the internet so

you can send them out of your company

and um

they're legal they're legally recognized

the numbers range from 2000 to 3 FFF in

the first 16 bits

current allocation there's there's

trillions of these addresses so the

current allocation has come in from

2001. this will this will last quite

some time obviously

there's a 48-bit provider prefix and if

you uh check the

images of the address packet you'll see

the 48-bit uh there's a subnet ID

you can submit inside the organization

if you wish subnet to IPv6 is a topic

but it's not in the CompTIA it is in the

Cisco ctna and then the rest is the host

portion of the address

now I'm sure most equipment can actually

do this but Cisco routers can

self-generate this part here

so what you would do is if you configure

an interface you would you would

basically configure whatever the address

is

dot b dot whatever whatever and then the

host portion here the interface would

um self-configure

so

um I've issued oh this is on my um

Windows computer for the looks of it

I've just issued an IP config or

forward slash all and I've seen the IPv6

address that's been allocated here and I

think Windows self-allocates these

addresses also

uh link local address the prefix for

link local addresses are feat these are

only valid between the link between two

IB V6 interfaces so you've got an

internal router and say for example an

ethernet connection here

then these addresses will be valid and

these two IPv6 routers

can communicate with one another using

this link local address what it can't do

is this address in here it can't be used

to reach another device out here

now if you've got another device the

link local addresses of these two facing

interfaces so for example fast ethernet

here fast ethernet here they will

communicate between one another here

automatically created once IPv6 is

enabled

now these are used for writing protocol

Communications IPv6 protocols mentioned

in the syllabus but I don't think I've

left it out for now because looking at

all the official guides there's no um

questions yet I will add it later on if

um if that changes though

traffic isn't forwarded off the local

link certainly not using the link local

address

so here's a configuration for a Cisco

router you I've enabled IPv6 routing

I've gone to the faster ethernet

interface all I've done is turned on

IPv6 for this interface here the fast

ethernet zero slash zero

I've typed end and then it I've said

show me this interface it's down I

haven't connected it to anything but as

we can see this address this link local

address has been allocated

self-allocated this is an important bit

here

FFF as we'll see in a minute but

basically this is my IPv6 address I have

an app to write it out manually at all

I've already um shown you the windows

one

yeah unique local uh it's the IPv6

version of private IP addresses so you

can use all of these on the inside of

your network you wouldn't be able to

Route them onto the internet don't think

these are used anymore I think they're

actually been depreciated

if you get a question in the exam here

it would be something like this what

prefixes link local addresses are taken

from fc00

uh forward slash seven for your subnet

mask

these depreciate site local addresses oh

sorry so site local addresses that have

been depreciated and overtaken by link

local a unique local so you'd use this

on the inside of your network if you

want to do any internal routing what you

couldn't do is use it out on your on the

internet though

multicast addresses are still used very

much in IPv6 this is the prefix so write

it down and put it into your studying

crumb notes

and multicast replaces address

resolution protocol for IPv6

a use for duplicate address detection so

when you first fire up your interface

I'll talk about neighbor Discovery in a

moment but I'll say just to save space

I'll say this is the address obviously

it would be the IPv6 address it will

this interface will advertise out this

address

to um

the network this multicast address

saying I want to use this address X and

if any of the any of these interfaces

are using that address so this is using

Y that's using Zed

it will come back and say no you can't

use that address but in this case my

example here nobody's using it

all routers must join the All host

multicast group of

ff02 and then whatever in the middle uh

one so it'll all be zeros and then one

and the all routers multicast group this

is how enable Discovery protocol works

so it must be allocated and listening to

these two addresses

and if I issue a show IPv6 interface

fast ethernet 0 0 you can say you can

see that it's joined these two groups

appear the um the F2 and the F1

eui 64 addressing is the new part in the

syllabus

yeah so I've issued a show ipv

IP interface sorry I've didn't do IPv6

because I want to see what the MAC

address is

because this is how eui 64 obtains the

um eui 64 address

so this is how or one of the ways you

can self generate an interface it uses

the MAC address

the 48-bit MAC address obviously we need

128 bits 48 bits isn't enough to

generate this address

but what it does it takes the MAC

address

it inverts the seventh bit and adds FFF

Fe in the center so right in the middle

of the MAC address it's going to add

fffe make sure you take a note of this

for the exam so

uh we've got zero zero one one

hold cover white it doesn't say zero

zero one one here and then here's the a

here

and then you can see the fffe has

appeared he has inserted it and then it

carries on with the rest of the MAC

address BB c c d d so b b c c c m c d so

this is how it pads out the address

so there's two bits Mac address

plus this but then it does this other

bit here which is inverting the seventh

bit

so

just to recap what I've already said

we're looking at this part now zero zero

one one well instead of that now we've

got zero two one one

all right so going into the seventh

seventh most significant bit

so this is our sample address here

the first two nibbles uh or is one byte

so this is 0.0 so a nibble if we have

one two three four five six seven eight

so eight bits is one byte which we've

covered already oops

one byte

one byte eight bits but what we can do

is kind of subdivide it in the middle

here

and we can have a nibble here

and a nibble here

all right so our first two nibbles one

byte here

is zero zero

which would have all the binary bits

basically pretty easy to work out

so this here

if you write it out with a nice uh

font is zero zero zero zero zero zero

zero zero so what we need to do is flip

the seventh most significant bit

so what we've done is one two three four

five six seven eight so this is the

seventh most significant bit and what

we've done is gone all the way over here

to find the seventh bit and we've

flipped it so whatever it was here in

binary we flipped it so one

flip two

sorry zero flip to be a one

now if you wrote that out uh this part

here

you'd have um

your zero would be covered two that's

the one two four eight one two four

eight Okay so we've uh enabled this

column here and our zero has flipped to

A2

and you can see here zero two one one

and then um this is the MAC address

we've got the fffe in the middle and

then the rest of the MAC address this is

how you work it out you might get a

question on this so this is why I

brought it to uh your attention and you

just need to practice a few examples

so what would this address be changed to

if you write it down

all right so I've just carried it over

to the next slide here

so Charlotte IPv6 interface we've got

this address here and we end up with

this global unicass address here

and you can see already we've got the

fffe

created here

so and because it's it might not show

you another

vendors but you can see here there's a

clue it says eui so we know eui 64 is

addressing

well C2 in decimal is 192.

or um in binary here one one zero zero

double one double zero in hexadecimal is

C

and if you've just got a one in the uh

two the two column here so one two four

eight you can see uh that's a two

see in hexadecimal is 12 so we've got 8

9 10 11 12. so I think we've covered hex

earlier so you swap the seventh bit

so one two three four five six seven

this bit has to be swapped if we're

doing the UI 64.

and then it becomes a zero if you work

this out zero zero zero zero the second

part is uh C zero so here we go c0 and

then it carries on as normal zero zero

instead of C2

so I know it's a lot to get your head

around just practice it watch this over

a few times and then practice some of

your own examples

applying it enter your desired subnet

and then add the command the tag eui 64.

this is how you do it in Cisco you won't

be asked about vendors or how to apply

it I'm sure I'm just telling you how it

works so I've added this address I want

to say we're using um

this subnet here this address and uh

double colon so I don't care what goes

there

64 and then I add the tag basically

saying you um you allocate

uh using the MAC address plus the

seventh

bit rule which will swap the seventh

most significant bit from a zero to one

or one to a zero

and here's the command on an actual

router so yeah you have to you can't

just say create the entire address for

the routable address

um you have to add this tag here

all right next is the neighbor Discovery

protocol which is a major feature of uh

of IPv6 this allows other routers on the

link to be discovered there's a couple

of messages you you need to be aware of

which is RS router solicitation like are

are any routers on the link this is the

router solicitation message

and it's sent out saying what what else

is here

the router advertisement is the reply

you'll get from the routers IPv6 routers

uh yep I'm here R A I'm here

it just give us prefixes so whatever

your prefix is on the network

Etc these routers will say we're using

this prefix and then this will be able

to Auto allocate an address so it can

communicate communicate on the subnet

so this replaces our we don't have ARP

working on the uh on IPv6 subnets

also works to duplicate address

detection which I've already mentioned

the device the ipvx ibv6 device will say

I want to use address X are any of you

using it and then there'll be a reply if

it is in use

so there was solicitation asking for a

neighbor's information

their neighbor advertisement you

advertise yourself out to Neighbors

the solicitation asks for information

about local routers these are the four

types that you need to know about router

advertisement advertise yourself as

active these are the four types so make

a note of them

the idea I've already mentioned the

neighbor advertisements are sent to

check if your address is unique this is

the address it's sent to which is the um

save as a broadcast address but we're

multi-cat we're multicasting in IPv6

no reply means your address is available

to use the amount of air seconds

should vary from vendor to vendor I

haven't read the RFC actually but if you

really wanted to you can read it

so you can see the advertisement is

going out with this address reply if you

are this address

using the icmpv6 packet

um and then the

advertisement here I am this address so

basically you can't use it

DHCP version 6 is used for IPv6 this is

for auto allocation of addresses

also used with uh it's used in

conjunction with DNS for IPv6

and here's the RSC if you've got some

spare time in your hands allocate IPv6

information to hose obviously the IPv6

is um

the Gateway the the DNS server

and another DHCP information

host can request it with an outgoing

router advertisement message

allocated and requested using UDP bear

that in mind because some people think

it's TCP it's Port 546 and 547

the other subject you need to be aware

of now is if you're running uh IPv6 on

your network and then ipv4 nobody is

going to

come into work one day and have ipv4

taken off and only even in IPv6 you're

going to have a transition period where

you're running both of these protocols

so what's going to happen is somehow

IPv6 host reaches an ipv4 router and

what you're going to have to do

is tunnel the IPv6

information inside

an ipv4 packet with a header and the

trailer running ipv4

there's a few versions isotap

uh

64 to the link

dual stack is when you're running both

at the same time

there's a static to null I think yeah

that's different to GRE you don't have

to know the config so don't worry about

it generic routing encapsulation has

been around a long time but you can use

that for tunnel in

automatic as another type you can choose

from

if you want to study more I recommend

everyone needs to do about

uh four hours

studying to IPv6 this is for interviews

technical jobs uh technical interviews

and just to do your day-to-day job you

do need to understand it there's a

course on them cartoon network.com it's

16 hours in total but I broke it down

into I think the beginner course is

about three there's an intermediate with

loads of routing

and then maybe I think five or I'm

trying to do my math now six to 12.

seven hours extra which is Advanced so

you could just do one part and then when

you come to do something a bit more

difficult do the second part and if you

want the third but um you really do need

to know IPv6 I've been talking about

this for about four years now and it's

becoming more and more urgent so you I

used to recommend it and now basically

the the level of uh understanding in the

the level of adoption is basically you

you have to know it it's just like not

knowing ipv4 now if you go into it um if

you go into an interview so please do

learn it and we've covered IPv6 address

types Navy Discovery eui 64 and then

tunnel in that's all for now thanks for

listening

[Music]

thank you

Network routing and IP addressing IP

assigning and addressing methods

so having discussed both ipv4 and IPv6

and the difference between these

different types of IP addresses we now

want to talk specifically and in more

depth about how IP addresses are

assigned to a specific node or client or

server so in this module we're going to

look at the two different ways that IP

addresses are assigned this involves

defining the first static IP addressing

static meaning that the IP address is

always the same and dynamic IP

addressing which means that the IP

address can change we also want to talk

about the strengths and weaknesses of

each of these addressing methods and we

want to compare the features of one and

the other

we're also going to identify when we

want to use Dynamic IP addressing as

opposed to static IP addressing and

Define when we're talking about Dynamic

IP addressing the terms DHCP the server

and protocol that are responsible for

allowing Dynamic IP addressing to work

something called the scope which lets

the DHCP server know which IP addresses

are up for grabs and then the lease

which just like the lease on an

apartment

lets the both the server and the client

know when a IP address can be used and

for how long we also want to talk about

when static IP addressing would be

preferred and as you can probably tell

from the way this is worded we generally

want to use Dynamic IP addressing as

we'll talk about but there are certain

instances in which a static IP

addressing is the best method for us and

we'll talk about those as well

so first let's talk about static IP

addressing it's done manually and that's

what this really means static means

manual assignment which means that I

literally have to go to the computer and

type in what the IP address is and how I

want to use it so there are two major

flaws with this first it can be very

time consuming because it has to be done

manually and each address has to be

entered individually by hand in addition

this takes a lot of time and it's prone

to a lot of Errors

human error is often a factor when we're

configuring addresses for a large amount

of systems and if you can imagine I'm

working in a system of say 5

000 computers then I'm going to be

typing in IP addresses a lot now while

this may be a worthwhile method when

assigning a very small amount of

addresses it's obviously not very

practical when I'm talking about large

quantities and the other major flaw is

that it has to be reconfigured every

time the address sync scheme changes so

for instance if I was going from ipv4 to

IPv6 on my internal Network I'm going to

have to re-change everything once I've

switched over or let's say I want to

change my naming system maybe I want to

go from a Class C to a class AIP

addressing system if I'm an ipv4 and in

this case I would have to then

reconfigure everything on each computer

and you can imagine the amount of time

that that's going to take

so due to its many flaws we're really

not going to use this method static IP

addressing which means again manual

assignment the way you can remember that

is that static does not change right it

remains constants

and the word static meaning not changing

is what tells us that so we're only

going to use that in specific instances

and I'll talk about that a little bit

later

so as a result it's very rarely used

except in very specific instances I'm

guessing you've never had to enter the

IAP address on your Soho router or at

your computers at home and that's

because we're going to use this other

method being Dynamic addressing now as

the name Dynamic implies the IP address

can change which means that it is

automatically assigned now this is a lot

more useful of the of the two that we

have for many reasons it's done

automatically through a protocol called

Dynamic host configuration protocol or

DHCP so you ever hear DHCP that is what

is referred to when we're talking about

Dynamic IP addressing this is part of

the tcpip suite and it allows a central

system to provide IP addresses to client

systems now since it's done

automatically there's no possibility of

human error and it's also a lot more

efficient than static IP addressing as a

result it's a lot more common of a

method

uh it also eliminates the need to

reconfigure a system if the addressing

scheme is changed so it's far more

commonly used because of all these

reasons like we just said

it's more practical and more efficient

because I don't have to change every

computer

all I have to do is tell the DHCP

service computer we'll talk about that

in a second

that we're changing everything and all

the underling computers automatically

are going to change

so if we move over real quickly

into our Windows system

and let's go into our Network

properties

and we'll go ahead and go to change

adapter settings I'm going to right

click on this and go to properties

now we'll see over here if I click on

tcpi P4 and go to properties it says

obtain an IP address automatically

so through DHCP the IP address is being

automatically obtained just like DNS is

also going to be given out automatically

now if I wanted to do it statically I

would have to manually assign an IP

address a subnet mask and a default

gateway for each device so you can see

where we're not going to want to do that

so let's talk a little bit more about

DHCP or the dynamic host configuration

protocol

this is the protocol which assigns IP

addresses and it does this first by

assigning what's called or defining

rather What's called the scope the scope

or the ranges of all of the available IP

address on the system that's running the

DHCP service and what this does is it

takes one of the IP addresses from this

scope and assigns it to a computer or a

client so for instance let's say that

we're dealing for simplicity's sake with

a uh

192.168 Class C Network so the scope

might be something like 192.168

dots one

dot 10

through

254. this means that of the IP addresses

it's going to assign it's not going to

take anything in front of the 10. so

this gives us dot 1 through dot 9 to use

for static IP addressing so what this

ensures is that the DHCP server is not

going to assign an IP address that we

have already manually or statically

assigned to another device we'll talk

about why we would want to do that in a

minute but this ensures again that the

scope

uh that the DHCP is not going to assign

an IP address outside of its scope then

what it does it takes this available

address and assigned it to the client

for a set amount of time and this is

called a lease so the lease says how

long

the IP address is going to last

now the reason that we had leases is

because remember if I turn off my

computer it no longer needs an IP

address it also means that let's say I'm

taking a computer away I don't if I have

a if it has a lease of forever then that

computer now has one of my available IP

addresses so sometimes we'll have an IP

address with a 24-hour lease or maybe a

two day lease but whatever that lease is

at the end of that lease it's going to

have to re-again ask for another IP

address this is also the way that we can

share a limited number of IP addresses

with a lot of uh computers or nodes

so when we had the internet we used to

dial up to the to our ISP or Internet

service provider what this would allow

is it allowed our

uh ISP to provide us with one IP address

that only lasted for a certain amount of

time and then when we disconnected the

IP address or disconnected from the

server and therefore didn't need the IP

address it could assign it to someone

else and it didn't have to worry about

us coming back on and wanting to use the

same IP address because remember one of

the rules is you cannot

have

two devices

with one IP address

all right now let's talk about how this

works from the client's point of view

basically what happens is I have a DHCP

server here and it has what's called a

trusted connection to the switch

we'll defined what a switch is

previously and we'll talk a bit more

about them later as well but it has a

trusted connection this computer say

comes online

and says hi

can I join your network

can I get an IP address it sends its

request through what's called an

untrusted connection

to wherever the DHCP server is now the

DHCP server at some point finds this

because this is generally a broadcast

because again it's not a unicast it's a

broadcast because this computer coming

on doesn't know where the DHCP server is

so it sends a broadcast message out the

DHC per P server then responds and

offers a lease on an IP address at which

point this untrusted or unassigned

connection becomes a trusted one now

when the lease goes out it's again

untrusted and so it needs to repeat the

entire process again

now so far we've been pretty fair to

DHCP and expanded on the benefits for

dynamic addressing but there are some

exceptions when a network is configured

uh for DHCP and we don't want every

single device to be automatically

assigned an IP address

for instance

um

the DHCP server itself needs to have a

static IP address this is because we

don't want the DHCP server to be

changing addresses and what's going to

happen is if we have a lease

theoretically the DHCP server could

change its IP address and since every

computer on the network needs to know

where to go that's going to have to

remain the same this is going to go the

same with the domain name server so the

DNS server which allows us to convert

between say google.com

and the IP address so we don't want to

have to find this every single time and

we have to set it as something specific

meaning static we're also going to put

our web server as some static IP address

this is the reason why if you wanted to

get an account with your ISP or internet

service provider and you wanted to run

and web server from your computer at

home you would need to ask for a static

IP address be because

that's the only way that someone can

link through DNS

to your web server and so our web

servers always has to be static because

when I type in google.com I always

wanted to go to one of a few different

IP addresses

finally printers are something else that

we want to have

the printer we don't want to move around

we want to be able to lock it in when we

install it on the computer same with any

servers also routers the Gateway

computer or the Gateway device that

allows us to get out to the network we

need that to remain the same so that's

why when we Define the scope and in

previous example we defined it as any IP

address between 10 and 254. we don't

want it to change

because we want these nine IP addresses

to be ones that we can assign now

sometimes we're going to make this a

little larger so that way

we can assign a lot more static IP

addresses so also maybe a wireless

access point we might want to be static

etc etc and all of this again is done

through a web interface or through

some sort of

router

device or through a terminal or

something so this is not something we're

physically hard wiring onto the device

because again that's that's a MAC

address a physical address but this is

something that we want to set through a

software of some sort

all right so just to recap what we

talked about we defined static IP

addressing again static means that the

IP address does not change

it also means that it had to have been

manually assigned

okay

now we also talked about Dynamic IP

addressing

which DHCP allows us to do and this

means that the IP address can change

because it is automatically assigned

one thing I didn't specifically talk

about what we referenced in previous

modules too is that a pipa address

that automatically assigned IP address

which if the dynamic IP address system

is not working so the DHCP server for

instance is down and it can't get an IP

address from the DHCP server it's going

to assign itself its own IP address if

you remember that was 169 about 254 dot

x dot X so if you see this is your IP

address then guess what your DHCP server

is down

we also identify the strengths and

weaknesses of each of these so um

we Define the static we Define dynamic

and then we identify the strengths and

weaknesses of each remember the strength

of dynamic is that

it's easy

and it requires less work if we change

anything

of course the Dynamics or the the

downside of it

could be this apipa or we don't want

um the IP address to change

we also talked about when to use Dynamic

IP addressing which is in most cases we

Define DHCP which allows a dynamic IP

addressing to work

scope which is basically the range of IP

addresses

and the lease

which is how long the IP address is

going to be

sent out for and then we recognize when

static IP addressing is preferred for

instance when we're dealing with

printers

or routers

or even the DHCP server itself

which we cannot have change

[Music]

welcome to module 6 lessons lesson 6 DNS

the name naming system

covered up we're going to cover a lot of

stuff in this presentation but I'll try

and get through as quickly as I can

what uh we need to know what DNS is what

our domains the fully qualified domain

name

the DNS root servers so what happens or

how does the system actually how do we

interrogate it and how does it update

itself

what are DNS records as well this is

stuff that's actually in the syllabus

now I'm sure you've already heard of

domain name system or DNS you can see in

the um output here the image we've

got.com dot org.us there's actually

loads and they're added um quite rapidly

and as each country has

um appealed for their own top level

domain more and more have been added so

there's lots of countries now that you

can register domain names for some of

them are protected for example

um if we go to.com

dot a u for Australia you actually have

to have a business uh number so

even if you live in Australia you must

have um it's called an ABN Australian

business number so not you can't just

have anyone having a DOT com.eu other

countries have got restrictions some

haven't so it just depends on where you

are so it's the name of a computer it's

got a an IP address on the internet now

these can actually be shared you can

have some of the same domain names if

you buy cheap hosting and they'll all be

sitting on the same IP address but this

DNS can deal with this

so yep that's just what I've said

if you uh

for example I used to host of these but

not anymore

uh

what was it called HostGator

I'm not recommending these by the way

you could have this guy's website

somebody else's another person another

person but they're all sharing

the same IP address but that's easily

taken care of

so what is it it resolves the names

associated with a server to its IP

address

so you can see on my home computer here

I issued a ping cisco.com well this

a URL is sitting on a server somewhere

and probably on spread among quite a few

servers actually but somewhere from my

home

wherever I am I've got to get through to

my

ISP and then obviously we've got a whole

bunch of other hosting companies

wherever they may be and then finally we

get to the building

hmm

that Cisco owned maybe Paulo Alto or

somewhere else but there has to be a

result between this and what actually

comes back because tcpip doesn't ping

names it pings uh IP addresses so 172

163 4.161 that could have changed but

something has to happen before the icmp

packet can be built and as you know from

other lectures he's got to have uh

inside their Source destination and

their data whatever else inside the

packet so DNS will take care of the uh

resolve for us

when we tried to access a

samplecompany.com from the web browser

DNS translates the domain name into an

IP address

so I've just put an IP address if you're

super super smart and got a great memory

you could basically browse the entire

internet just using IP addresses however

if it's something new for example if you

want to go to

xyzsite.com you're not going to know

obviously the IP address and this can

change over time by the way they can

move to another company and assimilate

with someone else or buy them out

so that IP address is used by our

computer to communicate with the

corresponding server on the network

as a database DLS knows about the

relationship between the domain name and

its IP address it's a distributed

databases spread across the world I'll

come up to this morning here but um

you've got your ISP which will probably

have several thousand of the most common

DNS addresses

and and mappings in there if there isn't

one there then when you do your search

at home

if it's not there then quite quickly it

will be forwarded to

like possibly it might not be the um one

of the root servers which I'll come to

but it might be an authoritative DNS

server that will hopefully resolve if

not then it can carry on

it uses UDP Port 53 just uh bear that in

mind because you could come up in the

exam

uh just people argue that it DNS doesn't

use

UDP it does for our for our purposes DNS

uses UDP now if you happen to be working

for an internet service provider then um

TCP is used but it's used for Zone

transfer so all the domain names that um

will be transferred across that

obviously has to be done reliably or

large requests

it can also be used if there's multiple

this depends how you've got it all set

up if there's multiple failures looking

for

xyz.com then it could also move to TCP

this is because it could be caused by a

UDP dropouts or fragmentation

but we probably wouldn't need to worry

about that for our day-to-day jobs

our DNS database or the DNS database

divided into sections called zones these

store name information about one or more

domains

and the domain is included in the zone

The Zone becomes an authoritative source

of information about that domain

so as I've already said we need our

routers and multiles which is we we

concerned about IP addresses to make

forwarding decisions so we had to have

this service created

uh you we know this stuff already

difficult to remember kind of alluded to

it

so the IP address with the domain system

we don't need to go through the headache

of remembering the IP addresses

a little flogging the flogging the point

a bit here

so the DNS name system is based upon the

domain name space

collection of unique names that denote

other kinds of information such as the

IP address now there has to be certain

rules in place obviously and these rules

have been added to and amended if you if

you've got the time and the inclination

to read through the rfcs and certainly

when we come to see Name Records

conical names I'm not saying that twice

they had to issue an update on the RFC

because people were getting a bit

confused about what it what it did and

this is one of the things about when you

when you create something and you write

the rules

of the documentation you

you presume people already understand

stuff because it's in your head this is

why it's handy to get other people to

write the documentation and then you

read it

and I'm saying that because

documentation is included in the network

plus the exam

so the namespace is a hierarchically

there's too many long words today

structured and has rules to uh that let

the namespace be divided into subsets

so in the land uh the domain is a sub

Network consisting of a group of clients

and servers I'm not talking about the um

your internal

um intranet for example

I'm just talking about the day-to-day

lands of IP addresses you could have the

intranet or obviously

um Microsoft also has a naming system

the active directory so we're not

talking about that

so Internet domain is a descriptor of

The Logical grouping of names and it

indicates whether the names belong to

the following commercial entities and

non-non-profits I'm not sure what the

non-profit is.org isn't it

which isn't isn't really the case

because

um I've got a DOT org website so it's

not protected you don't have to be a

registered uh charity

educational is dot uh Ed I don't think

it's dot EU it's dot e d u now I you

can't get these as far as I know

certainly not for USA you have to be um

a uni

College something like that so I presume

you have to have some sort of

documentation or number

government agencies.gov

and so on

you can subdivide the domain into groups

called subdomain

so the DNS domain can also contain hosts

these refer to computers and services so

we've got an example here

training.samplecompany.com

so this is the first obviously the top

top level domain which we talk about

then somebody's registered this

but then when you go into your

admin panel

you can add these sub domains here for

example my

I think it's called rack start

how to

network.com I've got the same sort of

thing I created this subdomain which has

got its own IP address at

howtonnetwork.com is sitting somewhere

um

actually know where it is it's sitting

on a server say say no

I IO the the um racks are sitting

somewhere else because I've used DNS

records that sit in in um oh

I actually remember where it is

up at Nevada just so you get the point

anyway

so samplecomedy.com the.com is known as

the TLD top level domain

okay so you could be asked this in the

exam this is ISA the fqdn the fully

qualified domain name is a complete

domain name for a specific computer or

host so it's got the host name and the

domain name

so for the fqdn for a hypothetical main

mail server might be mail one and you

probably have this if you're in a

reasonably sized company that's got a

dedicated Mouse server so you're

handling all your mail

most of these services are named you

know mail one mail two whatever and then

your company name so you're managing all

of your

um incoming and outgoing mail which is

probably

um a good idea

so you can Blacklist and and comply with

other legal requirements

so mail one is a host obviously you can

use more than one server you can use

virtualization whatever you want but um

hypothetically speaking it's a a server

dot com is the TRD as we mentioned

so DNS root servers these are the

contain the top level domain registry

that maintain the global domains so at

some point if you register a brand new

domain name

you'd register it with your

um

it could be with your hosting company

I'll just put HC and then that

eventually will get forwarded to the um

the TLD and then that will be forwarded

to non-root service So eventually your

ISP will probably

get a copy

so as of first of August 2018 root

server consists of 933 instances these

are operated by 12 independent route

servers if you're interested in more

information you can go to root

service.org and have a read up and

they've got some maps on there of where

all these root servers are

some examples of globaldomainsr.com or

netgov.edu country codes US Canada

CN

oh I don't know Denmark France Japan

CN oh that's going to annoy me now I'll

have to look when I finish this

presentation if he comes to me I'll say

uh you wouldn't be tested on that by the

way uh DNS root servers also known as

root name servers if anyone says that to

you it's perfectly um fine for them to

say that and it describes where the

authoritative did a service for the T

top level domains are located

please give answers for specified set of

zones from its own source so it doesn't

have anywhere else to go if there isn't

a response something's gone wrong

or the domain doesn't exist

at the moment and you'll you'll get some

sort of timeout message on your web

browser

non-authoritative servers these provide

cash dancers or Cash Aid I know some

people say that are obtained from

another name server

so as I said you've got the uh the root

servers here

and then

other companies large organizations just

to save traffic and time can query these

and then if they so wish

they could also be queried by other

servers and so on and so on and so on

the DNS is composed of a namespace this

is distributed database it contains the

data that includes the host names

if you recognize the structure there

it's similar to a file system in Unix

the name server translates the domain

name to its corresponding IP address and

we've seen an example of that

does the response to the DNS query it

receives from resolvers or the name

servers I'm going to talk about

um

to our resolvers in a minute I think I'm

not sure which slide it is

so the answers to the DNS queries are

based upon the contents of the name

server database so obviously the

database is full of records of um

mappings so um

x.com and it will be mapped to

there's a lot more than this but as a

simplified illustration

cached information is learned by the

name server from other name servers how

often they update the cache uh just

depends on obviously their local

configurations

now you can get an authoritative answer

this is based on the contents of the

name server database if it's a cached

answer it's known as non-authoritative

now on your PC you can issue

ip

config and this has worked for me before

and forward slash

flush DNS say I've moved my my website

from one hosting company which I have

done in the past to another

I can um I can force a flush to find out

where to to see if this

um it's been moved correctly

and obviously I could put the IP address

in

but this is quite a stressful time if

you own a business because you've got

your website

um technically in two places although

this is the old version and eventually

the records will update but uh could

possibly be asked in the exam ipconfig

uh forward slash flush DNS and try it at

home if you like

what's the DNS composed of as resolvo is

the next part which I mentioned it's a

software component that comes bundled

with your operating system also in

network Hardware

the internet applications such as web

browsers and email clients need a domain

name lookup so this is a piece of

software that um issues the DNS request

the resolver accepts the DNS queries and

if the required information is available

in the local cache it returns that data

to the client so your PC will use the

resolver

a piece of little piece of software

somewhere

then it will go out to the internet and

obviously return it so then you can

issue the ping which we already saw

and it's not available it sends the

query to the name server

when the resolver resumes the name

server's response it hands the result to

the application that initiated the

request so this will be your web browser

email

um email package whatever you've already

in obviously most of us are in our email

off the cloud now like um

Gmail

so internet application sends a query

for translating the sampler company

resolver checks the local cash so you

you could actually check your DNS cache

on your home computer

if it's not available then it hands over

to the result the resolver hands it over

to the nearest name server which would

be normally your ISP

name serversy determines whether it can

provide the data

if it's not available then it goes all

the way off

so PC

resolver

which basically just checks your your

DNS

cash on your home computer if not it'll

go off to your ISP if the ISP doesn't

know

it could query another server but let's

just say it goes off to the the air

route there so this would all happen

pretty quickly obviously you've you know

yourself you've put in a URL and just

sat there in how we're so impatient

nowadays you sat there in any more than

five seconds you start hitting the

refresh button

all right so the name server ask the.com

name server and gets finally gets the IP

address

since the sample company has the IP

address in its own database uh this this

would be for a new domain I guess the

name server that requested the IP

address now gets an authoritative IP

address as the answer

and that's all finally relayed

you could have a couple of query types a

query received by the name server this

is a recursive query this is received by

the uh received from the resolver

non-recursive is received by other

servers so they could just be doing an

update of their own records

uh probably in the exam you'll be asked

a little bit about what are DNS records

what do they consist of

also known as resource records these

have the information that we need to do

the resolving

the records map a domain to its ipv4

address these are a records

so this is the type of question you

might get asked what has an a record it

maps The Domain to its high people for

address

so here's an example you would put these

in when you register your domain name if

you host with the same company that you

register so there's a company called one

two three reg dot Co dot UK that I used

to register my names with and host so I

think it was all done for me there

now some of these domain names

um say in

60 days.com

I um had it registered here but it's

actually hosted somewhere else now so

about to go in and

um I actually put the name server that's

the only part I've put in but there's a

there's other records I can manipulate

and as the owner of this domain I can do

that but just be very careful what you

do if you don't know what you're doing

then you need to ask for help because

things can go wrong because as I've told

you you can split

your mail

to go to oneip address your

um your web server can be hosted on

another IP address you've got to have

records for all of this

so example of an a record first is used

to take care of situations when someone

tries to access the domain name without

typing www most of us don't bother now

so it'll resolved correctly the the

first one being

they say ah sorry

so somebody hasn't put www

and this is um this is a wild card so

anything before your domain name is just

going to go to and whatever server

they're hosting it on here

the second record we saw is the wild

card it will direct any subdomains to

the hosting server if you so wish you

can then point it off somewhere else or

you can add it into the DNA DNS records

the quadrupalade if there's any quick

way of saying this actually AAA oh could

you play

because um over in Australia this means

the Australian

um Automobile Association I know it's

Triple A we've got over here so you're

just gonna be careful what if anyone

else is using these uh letters

this is an IPv6 address that maps The

Domain to its IPv6 address obvious

obviously because um we need to be we're

moving to IPv6 now

so the 128-bit address

there's an MX record which you probably

won't be touching unless you're doing

your own mail stuff

to Maps the domain name to an email

server if you're working for a big

company they'll take care of that

but looking at the MX record we could

identify the mail server to which the

emails are sent

uh C name conical name record

used to specify a domain name or

subdomain as an alias of another domain

so it allows the mapping of a domain to

another domain

so for example

um

you complete subdomains such as the mail

or your FTP to your main address and you

can do you could do this to make your

company look bigger

and I think my FTP certainly just points

to my my normal server

yeah but obviously when you're doing FTP

you need to specify

um in your software that you're using

FTP so this that was that's how it would

work

so there must be an a record for the

hosting server before aliases can be

added

so cname aliases must point to another

domain

so if somebody types

um

bar.example.com there's a cname record

that basically says that is actually on

um

the C name is food.example.com then the

the search takes place the DNS search

takes place for food.example.com there's

an a record so IP B4 record and it's

saying yeah this is posted on this

particular server

PTR records pointers Maps like pv4

address to a clinical name for the

purposes of the reverse DNS lookup

so this is uh the reverse so normally we

do

um

xyz.com and that goes to

but the reverse can happen somebody

could type

192.1.1.1 when you type that in your

browser I think

you um

I need to test that actually

it won't stay so if you if you type that

you may well see it actually resolves to

this

might depend on your browser software

SOA State start of authority record it's

the first record in the zone file it

declares it contains the most

authoritative information for the zone

information is the email address of the

administrator you normally have to put

something in unless you want it to be

private the name of the primary DNS

server there's a serial number time

Fields when it was all registered and on

their last updates

uh two of the types of Records static is

when it's done manually

here and dynamic it's automatically

updated there's two types of Records

and Dynamic DNS this is a process of

automatically

um updating a Dynamic DNS record in the

name server what can happen is this is

all almost

in real time

could well be used if you're using cloud

computing and your setting up servers

tearing down servers moving information

Dynamic DNS

will update the lap information and the

um names

so useful when the IP addresses of our

devices keep changing

uh whenever a client computer using DHCP

gets a new IP address it can use Dynamic

DNS

all right so we covered a lot of stuff

you know the core stuff about root

servers and AE records and quadruple a

records I think that's the type of stuff

that has questions on

DNS domains fully quite fully qualified

domains root servers records a lot of

information and thanks for watching

[Music]

thank you

welcome to module 6 lesson 7 proxy

servers

objectives we're looking at what a proxy

server is an introduction uh the uses of

proxy servers and forward proxy servers

reverse proxy servers

so you may have actually heard of these

before especially if you've worked in an

office whereby

instead of connecting directly out to

the internet your settings will be

searched that you'll connect to a proxy

server especially

um for getting out to surfing websites

the proxy server will do a few things

which we'll look at in a bit

so it's in a mediator or an intermediary

between you and some other service

you've got the client computer the

destination server and then obviously

the proxy in the middle

here's an illustration here which we'll

talk about the caching and web filter in

so it's mainly uh used for uh surfing

when you want to go out and surf the web

for whatever reason it can then filter

what sites you can and can't connect to

it's um

caches some of the content so it's got a

copy of regularly visited our websites

to speed up the um

the surfing experience for you

makes requests on behalf of the client

computer so you're sending the request

out to you to what you think is the

internet but it's going to the proxy and

then the proxy design your behalf the

proxy receives a response from whichever

server say the web server on the

internet and then sends that information

back to you

so it intercepts the communication

between the client's computer and the

destination server

I've already mentioned that you don't

actually directly connect to the

destination you can have different proxy

servers to serve different traffic needs

you might have a proxy server to handle

only HTTP and then if you're doing FTP

then it may handle those requests and on

a different server

what does it do it increases performance

so

um it's mainly due to caching or you may

have quite a powerful proxy server

that's done doing all these requests for

you

increases security because what the

outside servers on the web see is the

connection coming from the proxy are not

actually and the uh the client device or

the host device

it also as I said caches content so it

can serve up and saved copies of a

website it could be a News website or

something else that may not um be

updated too regularly and then whatever

these rules are on that proxy server it

will refresh that content at given

intervals

so you've got to be careful sometimes

you can actually be served up a cache of

a web page and the actual live website

has changed so it's something to bear in

mind when you're configuring this on

your network if you do it

crazy security as well filters our

unwanted web traffic malicious files

before sending that onto the end client

if the client tries to download a

malicious file unknowingly the proxy

server can filter it out and you can

have a firewall in between your proxy

server and a client or between the proxy

server and the internet or both

depending on what your requirements are

so already covered that actually

a forward proxy server is a new thing on

this syllabus it acts on behalf of a

client computer it gets the requested

information from different servers

servers on the Internet only interact

with the proxy server and they don't

know about the client's existence which

is the concept we've already been

discussing now there's something

um known as a reverse proxy server

and the clues in the title I suppose it

acts on behalf of the servers on the

inside of an organization but you can

see here

some host on the Internet is trying to

access your web server internally and

the proxy server will act as the

intermediary deciding what does and

doesn't go out and also obviously it

will could have cached copies of what's

actually on the web server the actual

web server on the inside

so um since the service is behind the

proxy server the following is true the

client is not aware of the services

existence this is the internet client

wherever that may be and it treats a

proxy server as the origin

foreign it can also be used to balance

the load under server farm so it can

pull different servers at the same time

or load balance

now the servers are considered to be on

the server side of the internet because

of the following The Intercept all the

traffic coming from the internet they

make it more difficult for hackers not

impossible but more difficult to get to

get the details of the internal Network

all right so in brief we've covered

proxies and introduction the uses of

them forward proxy servers and reverse

proxy servers

all right that's all for now thanks for

watching

[Music]

welcome to the lesson on network address

translation on Nat for short

and a look at what it is ipv4 addresses

IPv6 addresses

benefit of having NASA using it

Source Network address translation

destination that and port address

translation or also called Pat or Nat

overload

so what is in that

it basically translates in private IP

addresses into public IP for addresses

the private IP for addresses

um

RFC 1918 I think it is these provide

addresses that you can use internally on

your network but they can't be routed

over the Internet so all of a sudden

you've got a problem

so this helped solve the issue of

running out of ipv4 addresses however

then we have to resolve the issue of not

being able to wrote route those

addresses

so and that is a router function

actually these routers and firewalls can

do nothing

so normally it's enabled at the boundary

where your local area network meets your

internet connection

you don't need to bother not in usually

internally on your network no particular

reason and we use Nat with ipv4

addresses

ipv4 has approximately 4.3 billion

unfortunately the DraStic growth of the

internet due to affordability of and and

user equipment basically I mean maybe we

were running out of ipv4 addresses

so Nat was a temporary solution to a

permanent problem

IPv6 is the replacement obviously for

ipv version 4. now this is the long-term

solution there is a version of nat

available for IPv6 I don't even think

Cisco included on the syllabus anymore

the reason is there's an almost

inexhaustible

number of available IP version 6

addresses

um I think something like Millions per

every per every person in the world so

it's pretty much inconceivable that

we're going to be running out of them

anytime soon certainly within our

lifetimes anyway

so it benefits as well as using it so we

don't really have addresses it actually

hides our internal addresses on our

private network from the internet which

is pretty handy so it's a security

feature

these are the private addresses which

hopefully you're already familiar with

you need to know this range of addresses

because this is a favorite exam topic

for comtier and also Cisco and Microsoft

these addresses you can arbitrarily

inside them with the dhp server inside

your network or

um yeah you'll have DHCP server

somewhere usually

I wouldn't let any users assign their

own IP addresses

so let's say we have a lan with

computers that assign these private IP

addresses and internally we've got a PC

one the data back it goes to our router

the router will Nat to this address for

a routable address which you've added to

the configuration somewhere

and it's one of the addresses you've

been allocated the packet goes out to

the internet somewhere comes back your

router will have a table and that

translation table

and it will recall which address on is

on the inside which is on the outside

and then

um re-nut it so it populates the packets

for the correct header and then forwards

it back to the

um PC on the inside of your LAN

so in this case this is in Long longer

version of what I've said really this

case the hudternetwork.com so if I have

the server on the right there a scene

that it's coming from a routable IP

address

it just wouldn't get routed by your um

ISP otherwise

you can tunnel addresses but you still

need to Tunnel them inside a routable

packet

Source Network address translation a bit

of a strange term this but comps here

are coining it

basically it means the um Source on the

inside of your network is being nattted

out to a routable address so you're

initiating the connection from your

source

so you've got a 192 Network and it's

been translated to a range of addresses

on this router probably not a good idea

to have one routable address because you

can only ever have

uh one connection live from the inside

to the outside

so I've covered that and since the

source private IP address is replaced

with an external public address it's

called sourcenat

to be honest I've only heard um the term

that's used in all my years on

networking but you need to be familiar

with this because they've put it in the

syllabus for some reason

okay so I've covered this the other

thing is destination Nat this is where

the connection has been initiated from

outside the network

and say you've got some sort of internal

um web server that serves members of the

public who want to find out more about

your company you normally have this off

a DMZ on a router interface also or a

firewall somewhere so this time the

packet has come from and the in the

internet

and it's hitting your router and your

router has a map in so this will be a

permanently permanently featured address

um a mapping inside your router or

firewall

now if you look at this image it's

probably would make more sense just to

have a routable address anyway on the

inside of your

um Network somewhere in the DMZ

the demilitarized zone which is a safe

zone for

external hosts to access that isn't on

the same interface as your local area

network that would probably be a better

idea but otherwise this destination that

is an option here

so I've mentioned dmz's

uh through our public facing server

Although our public facing server has an

internal IP address the users on the

internet obviously cannot connect to it

which we've already covered so dnat to

destination that is the solution there

you can use destination app for load

balancing

um the traffic coming to servers from

the internet so you could have three

servers low balancing

um lots of web connections coming in and

there's different types of device you

can actually use for this

um and so it's all getting load balanced

to one routerable IP address but then

two three four or more and non-routable

addresses on the inside of your network

so when the user sends a packet it

changes the destination public IP

address and to one of the internal

private IP addresses

the last thing is Pat which is actually

used more often than that

port address translation normally when

you have a small company you'll be

allocated a single IP address but you

still want to do nothing so what this

does is it uses your oneop address but

uses port numbers after the IP address

for source and destination

so this is the this is the solution

normally

um for this solution here you'd have a

static IP address in one to one but you

can't afford that for whatever reason so

you've just got one IP address

externally but several hosts on the

inside

so what we have is a port number for

example 192 168 1.3 and then a port

number your connection would go out

on a specific port number for example

Port 80 if you were doing a web

connection but it would come back in and

then get changed to a a random port

number or you can configure a range of

usable port numbers that are outside the

well-known port numbers of m0 to 10 23 I

think it is

when the internal host of the private IP

address initiates the session it will

generate a TCP or UDP port and that's

just unique to that session so you can

see here internally we've got Port

15345 externally two zero two zero one

to be honest it would normally be a

well-known port number such as a FTP DNS

or web traffic

yeah

this port um mapping is kept on a table

inside the router it does expire after a

while just to clear the table but

normally

um more than enough time for you to

complete all of your sessions but that

end table expiration time can be altered

on the router

all right so now at ipv4 IPv6 which is a

solution to address to depletion but we

don't really use that much at all with

IPv6 some of the advantages remember

security and also you get to use lots of

addresses on the inside of your network

and and up and and one address or more

on the outside of your network

all right so that's all for now thanks

for watching

[Music]

tcpip

tcpip simple services

in the previous module and lesson we

discussed the way that IP addresses are

assigned now in this next lesson we're

going to be talking more about the tcpip

suite and specifically in this module I

want to discuss some of the simple

services that are in the tcpip suite

what they do and what some of the output

might look like for some of the services

and why we might not see output for some

of the other services

now you might see this on the exam and

you might not but either way it's a good

thing to know about and just in case

now first we're going to talk about all

of these different simple tcpip services

and in some cases we're going to

demonstrate them and just to give you an

overview of what these are these are

cargen or charge in or character

generation

the daytime service

the discard service

the echo service and quote of the day

service now some of these happen in the

background are sort of embedded into

other protocols and services that we

might have seen but these are important

again to know about in a sort of General

way

so

the five uh simple tcpip services are

listed here along with the description

of what it is they do

cargan or character generation or charge

n or whatever the uh preferred way that

you want to pronounce it is is

essentially what you get anytime you

choose the option send test page to a

printer it's made up of ASCII characters

and ASCII again stands for the American

Standard code

for information

interchange so this is usually used as a

debugging tool when you're uh creating

or troubleshooting printers or print

test pages and so what it does it

literally just generates characters and

we'll look at this in a little bit the

next one is the daytime service that ATM

service is usually used for checking

errors or changes that happen within a

system's internal clock it presents a

message with the exact time that a

change was made or an error occurred and

we'll look at this format in just a

minute but basically what's important

here is that the output from this can be

used for for instance the Event Viewer

sort of what provides information to

that and if we're going to see it in a

um text based mode you will see exactly

what that's going to present in the next

slide now the discard service so we've

talked about

character generator and daytime the

discard service is basically used for

messages and information that are not

important and therefore should be

disposed of it discards these messages

automatically when they enter this port

or the port that discard is working off

of this can be useful when you're

configuring a system and using test

messages that you don't want necessarily

to display

so note that because the messages are

immediately discarded there's really no

response message that's issued and

therefore I can't show you an example of

one but just realize that discard is

going to usually be used for network

setup and configuration

and is going to make sure there is no

response or acknowledgment

now echo or the echo service sends an

exact copy or an echo hence the name of

any message that enters its port to a

place in the system where the message

can be monitored so this is often useful

for when you're monitoring things that

are going on in a network because the

echo service simply Echoes and copies

and forwards any messages it receives

there's really no way to show what an

example would look like because they

each look very different from each other

but basically in many cases we're going

to get some sort of message that happens

internally and we want the computer to

tell us that message once again so we

can see what's going on internally and

that's when we're going to use the echo

service finally the quote or the quote

of the day service sends a short message

that's been selected by the

administrator of the system to a

client's device now this service is used

primarily for checking the connection to

client devices so it's really similar to

like Echo the content of the message is

not this is not what's important what's

important is that

it is sending something and that way we

can make sure that the service is

working and that the um

troubleshooting is sort of easily

solved now as it mentions here it can be

taken from a specific file

right in here which is where random

quotes can be taken of if you remember

or if you know the hosts file it is also

located

in this folder

so let's take a look at this character

generator uh and some output that it

might give you

now this is what a test code page would

look like these characters are used uh

and they are the 95 printable ASCII

characters as you can see

from here and basically What's Happening

Here is that when I uh for instance and

this is someone going into telnet so

they've talented in

they have connected and now I've told it

basically to create some characters and

that's what it's doing here and it's

using all the characters that are

available to it in ASCII

and you would usually use this when

you're setting up a printer testing a

connection to a device or printer it

doesn't really have much of a function

otherwise you can see that the content

is not very important but all it's doing

is basically creating characters or

content for us to test with

the next one is the daytime service

report and this is what it looks like

and you can see that it's presented in

the following order it's going to show

us the day of the week

the months

the day

the year

the hours minutes and seconds in that

format and finally and very importantly

the time zone the reason the time zone

is important is let's say that we're

looking at this daytime in an email and

sometimes the headers are going to use

this same format all right that's

provided by the daytime service and

tcpap well I can see that oh yeah it was

sent

at 1845 which that's military time so

this would be 6 45 PM in sort of our

lingo but by knowing the time zone I can

actually determine where in the world it

was sent from and therefore for instance

this was sent on Pacific Standard time

which is in the U.S then uh I would know

that this is three hours later or 9 45

in the Eastern Time Zone

now none of the other uh as we've

mentioned none of the other uh Services

have any sort of output I can show you

but just to recap

what we've talked about we described and

demonstrated really briefly the TCP

simple services and these again include

a character generator we're really going

to see this a lot when we're dealing

with printers it's just generating

ASCII code

we looked at the daytime service which

is presenting the day

the time and also don't forget the time

zone which is really important

we looked at the discard service which

automatically deletes

messages that we don't need and so

there's really nothing there

Echo simply repeats

or Echoes any services or a message that

are happening internally and finally the

quote of the day takes a random quote

selected by the administrator or taken

out of a etc folder in the system 32

quotes area so that would be if we had

the root

which would be like system 32

and then Etc and then quotes that's

where it's going to draw something from

and again this is also used for

troubleshooting purposes

I showed you examples of these two

because they're the only ones that have

their own format all of the others the

form is not as important all it does is

take other information sort of

regurgitate it

now in the next module we're going to

take a step further and talk more about

some of the tcpi tools and commands and

get into the operating system when we do

so

[Music]

thank you

tcpip

tcpip tools and commands

so in the last module we talked about

the simple services that tcpip provides

and those you may or may not see on the

network plus exam

however in this module we're going to

talk about some of the most essential

tools when it comes to the tcpip suite

and I can almost guarantee you you're

going to see these on the exam so we're

first going to discuss and demonstrate

all of the tcpip tools and some of these

tools include the Ping command and some

of these we might have seen previously

as well perhaps an A-Plus and some of

these also I'll go into the operating

system and show you so we're going to

see the Ping command which basically

tests

for connectivity

we're also going to look at the trace

route command which basically traces a

ping

route

and remember when we were talking about

um uh protocols previously we mentioned

the icmp protocol

the control messaging protocol and that

is what a ping and a trace route command

use or these types of packets

so we're also going to look at a

protocol analyzer not necessarily a

command line tool but something that

allows us to analyze the protocols uh or

rather the packets that are going in and

out of a

network or system

we'll get a port scanner sort of does

the same thing we'll talk about the

difference between these two

we'll also get something called nslookup

and

NS doesn't ring a bell with you that is

like DNS or name server lookup

how we convert between an IP address

and a fully qualified domain name such

as

Google

we're also look at the ARP command which

allows us just like NS DNS which does a

name to an IP address ARP is what is

responsible for routing and allowed us

to convert between an IP address

and a MAC address or physical address

so you can see where this is really

going to come into uh into handy when

we're talking about routing and switches

finally we're going to look at the route

command which can present us with

routing tables

and it's specifically more or less used

when we're dealing with routers not so

much in Windows

all right so first the Ping command the

Ping tool in the Ping command are

extremely useful when it comes to

troubleshooting and testing connectivity

basically what the tool does is send a

packet of information in that packet

again is icmp

through a connection and waits to see if

it receives some packets back this is

not unlike when you used to see the

radar screens on a computer on a TV or

program we're talking about with um uh

submarines for instance and you would

see basically a submarine here and you'd

hear a ping

coming off of that so it gets its name

from that sort of sound so the data

literally bounces or pings right back if

there's an established connection

can be also used to test the maximum

transmission unit or the mtus and

remember we talked about that when we

dealt with an MTU black hole was in a

previous lesson this is the maximum

amount of data packets that can be sent

over a network at any one time or the

maximum size of that data packets so

using this you can test the time it

takes in milliseconds for data to travel

end to Android to other devices on the

network

this can also be done on the localhost

and you remember the localhost is

127.0.0.1 that's the IP address for it

and we can test this all by opening the

command prompt and typing in ping and

then the IP address

so let's take a look at this uh for just

a second

if we're here and we have our Command

Prompt and I wanted to type for instance

ping 127.0.0.1

which would be the Local Host

I can tell that my time is less than one

millisecond which makes complete sense

since there should be no loss of data it

should take no time and you can see that

no loss of data right here

right because we're sending it there and

back and obviously we're dealing with

ourselves the local host or the 127.0.01

so it shouldn't be an issue and if we do

that notice that when I use localhost

I'm using my own name and and it's also

giving the IPv6 IP address here now if I

clear the screen for a second I can also

for instance ping google.com and you'll

see that it actually sends first it

figures out what the IP address is and

then sends that and it gives us the time

that it takes

to get there and back it also gives us

some statistics for instance it was sent

four of them were sent for them received

zero lost and so we know that on average

this is taking 13 milliseconds to get

from us to Google and if you imagine

that this was a local host uh or rather

a sorry a local uh server on my network

and I was rebooting that server this

could help me tell whether the server is

back up again and one of the things I

might want to do with that and I'm just

going to use

The Local Host right now is use the

slash T

um

switch and what this will do is it'll

continually ping the same IP address

over and over again now I so for

instance if I was waiting for a server

to come back online this would be an

easy way for me to tell whether it's

come back online or not and I could exit

that by pressing Ctrl C all right

so the next one I want to talk about is

trace route which actually goes hand in

hand with ping because he also uses that

icmp data packet or

protocol it basically tells us the time

it takes for a pack to travel between

different routers and devices and we

call this the amount of hops along the

uh the network so not only tests where

connectivity might have been lost but

it's also going to test

um

the time that it takes to get from one

end to the other end of the connection

and it's also going to also show us the

number of hops

between those computers so for instance

between me and Google there might be

four different computers and so

each one of these is called a hop

and we can measure how far the packet is

traveling before it gets back to us

now I can also use this to test where a

where a downed router might be or where

in the connection a down to router might

be so if we go in here for a second and

let's take a look at the command prompt

here

and let's say I go to trace route

google.com now what's going to happen is

it's going to start saying all the

different hops going to tell me how long

it takes to get from one place to the

next and we can see also where it's so

right here we're still in New York let's

see NYC I can probably guess this is

some place in my ISP and now it looks

like it's starting to go out get further

out and we can see that the amount of

time it's taking is also more and more

so between getting between me and and

Google you can see how far we're having

to go until we finally get to the

google.com web uh server which would be

right here and we know it took about 10

hops

now you can see it has a maximum of 30

Hops and we can actually set that in the

switches if we need to but I wouldn't

worry about that for the exam

and just to show you what it looks like

if I'm tracing the Local Host you can

see it only takes one hop obviously

because or not even a hop because it's

myself I should be no route to get to me

now going away from the command line for

a second I want to talk about what's

called a protocol analyzer or a network

analyzer this is an essential tool when

you're running a network it basically

gives you a readable report of virtually

everything that's being sent and

transferred over your network so these

analyzers will capture packets that are

going through the network and put them

into a buffer zone now this buffer zone

just like the buffer zone we're dealing

with YouTube or Netflix and buffering a

video is going to hold on to these

packets and we can either capture all

the packets or we can capture specific

packets based on a filter

it can then provide us with an easy

readable overview of what is contained

within each packet this allows the

administrator total control of what does

and doesn't pass through the network and

can also stop potentially dangerous or

unwanted pieces of data to pass through

the network undetected

and so what you can see here is if this

is our cloud or our Network we're going

to call this a TCP Network just because

this is basically our our Wan and here

let's say I have one Lan and another

land I'm going to have a protocol

analyzer a network analyzer in between

my network

in my land that way I can analyze

exactly what's going on some ways this

might also take the form of a firewall

now this is different from what's called

a port scanner a port scanner does

exactly what it sounds like it basically

scans the network for open ports either

for malicious or for safety reasons so

it's usually used by administrators to

check the security of their system and

make sure nothing's left open oppositely

it can be used by attackers for their

advantage so uh if a poor if I'm on the

internal I might use a port scanner to

scan my firewall to see what's going to

be allowed through I might also put my

port scanner over here and have it try

to come in alternatively a hacker could

use a port scanner to go through and

scan for open ports if there are any

open ports it can then use those

to try to get into my system so I can

use it either as a white hat

or as a black hat

white hat means a good hacker black hat

means a bad hacker

now let's get back into uh our command

line for just a second here the name

server lookup or NS lookup and again

whenever you see NS as in DNS domain

name system you can think that has

something to do with name server or name

system it's used to basically find out

uh what the server and address

information is for a domain that's

queried it's mostly used to troubleshoot

domain name service related items and

you can also get information about a

systems configuration now dig actually

does the same thing but it's a little

more detailed and it only works with

Unix or Linux systems so here's an

example of what the NS lookup would look

like and you can see if NS look up here

and then what did we do well we asked it

for Wikipedia's name and up it pops the

IP address and it also tells us when

whether it's authoritative or

non-authoritative authoritative would be

a DNS server that's somewhere out on the

internet that is definitely has all the

information non-authoritative means it

might be a local one so if we were to

look at this for a second for ourselves

let's do NS lookup to go into the

utility

and now we could for instance look up uh

google.com

and it'll tell us all the different IP

addresses that are available for

google.com

yahoo.com

maybe even microsoft.com

CNN.com

etc etc so you can see all these

different ones that are coming through

now notice that CNN.com actually

wouldn't let us out and neither would

microsoft.com that's because they're

actually blocking the they're filtering

out the type of uh ports or protocols

that are going to be allowing uh that

are going to allow like the icmp Ping so

if we were to go out of this for a

second

and by the way you do that as Ctrl C and

if I tried pinging microsoft.com you'll

notice

that it actually doesn't come back and

that's because they're actually shutting

out icmp packets from going in

now another one related somewhat is

what's called ARP or address resolution

protocol we actually talked about this

previously and it's you really use to

find the media access control or Mac

address or the physical address for an

IP address or vice versa remember this

is the physical

address it's hardwired onto the device

the MAC address is the system's physical

address and the IP address is the one

again assigned by a server or manually

assigned in a way this would be like

your phone number

and this would be like your social

security number which is given to you by

the government

the way it does this is we're actually

going to send out Discovery packets in

order to find out the MAC address of a

destination system and once it

establishes that it sends that Mac

address to the sending or receiving

computer now the two computers can now

communicate using IP addresses because

they can both actually resolve to IP

addresses so basically I want to send

something

right so what I'm going to do is I'm

going to go out hit a router the router

uses arp in order to get the MAC address

to the sending computer and now we can

talk directly

because now I know what your Mac address

and IP address equal

finally

the route command is extremely handy and

can be used

fairly often it basically just shows you

the routing table which is going to give

you a list of all the routes network

connections and so on that the user has

the option to then edit now the reason

you might want to edit it is if for

instance in your router you want to tell

it to use one route instead of another

so an example here

shows us The Gateway

the mask

so draw these really quickly

and the interface and the sorry the

metric

as well as the interface and these are

all numbers so these might not mean a

lot to you but if you had a guide and

you knew where they were going if you

knew what your interface was for

instance is it a wireless internet base

or was it a your wired interface that

would prescribe a specific number

the Gateway is going to say what Gateway

you need to get out and the subnet mask

and you could actually add

specific information to this to create

your own routing table and this you

would do really not so much on your

computer but more if you're working on a

router say Cisco router so you can do

to tell it exactly where you want

information to be routed

so just to recap we discussed and

demonstrated several TCP tools including

ping which we're really going to use to

test connectivity

and remember you want to hold on to the

Slash

t-switch which is going to do it

indefinitely trace route which is going

to measure the Hops and can also tell

you where

uh connection has been lost a protocol

analyzer which is going to look at or

network protocol analyzer we're going to

look at all the protocols coming in and

can actually filter them in or out a

port scanner which can be used to show

open ports either as a security

precaution or if I'm trying to

infiltrate your network the NS lookup

which is that name server could also be

dig by the way which is on Unix systems

and this is going to allow me to get my

IP address to a fully qualified domain

name

ARP address resolution protocol which is

specifically going from IP address to

MAC address it sort of really allows

routing to occur this is really a

principle in routers

and finally the route command which

allows us to edit the routing tables and

would be really useful if I was using

one of my servers as a router you're not

really going to see routing a route

command on the network plus exam but I

guarantee you'll see all these others

mentioned

so uh now that we've finished up this

very brief lesson on TCP the tools and

the simple Services we're going to go

into Lan Administration and

implementation a bit more in depth

[Music]

thank you

foreign

Network Administration and

implementation

so in previous lessons we've discussed a

lot of the tools the networking

fundamentals the theory and so on and

now we're going to get into a little

more of the Practical side and that's in

creating and maintaining a local area

network wide area network and so on and

so forth this module is certainly just

an overview of local area network and

some of the best practices that go along

with it as we get more in depth over the

coming lessons and modules we'll talk

more about the specifics and what we

need to do

so in this module we're going to talk

about an overview of a lan kind of go

back over what it is and also

um when we'd probably want to use one

and then we're going to identify the

steps to setting up a lan including

using a network plan having backups

creating proper documentation auditing

and security

so first what is a lan well there are

two types of networks as you recall one

is a lan and the other is a Wan a land

stands for again a local area network

and the local area network is really any

sort of local or geographically

um

uh specific Network now Wan stands for a

wide area network and we're going to

talk about that in more depth in the

future so because Lan is restricted to

one geographical location such as a

school or a small office building it's a

lot easier to administer and requires a

certain specific set of skills since

it's so localized it also has higher

speed capabilities than a Wan and it's

often a lot less expensive so here's an

example of a local area network the

internet connectivity comes from the

server

which is going to also go out

to the WAN which would generally be

represented by a cloud the WAN being the

internet and we can see that there is a

switch here which connects each one of

these PCS

wirelessly perhaps has a PC connected

through it thanks to a wireless access

point perhaps connected to the switch or

router by the way here this server is

acting as a router and we might also

have the network connected printer very

simple but effective Lan here

now at the heart of every network is a

server the server is really what powers

the internet connection to every device

that's on the network and provides

um

devices on the network with resources

and other sorts of information now in

some cases we're not going to have a

server network but we're going to assume

here that we're talking about very

technical Network okay and the first

step to implementing a local area

network is to generally set up the

server or if we don't have a server to

set up the router

or the Soho router in a small office

home office remember the server is

really going to serve up resources

it's going to serve up a DHCP server so

on and so forth so the word Server

doesn't necessarily mean a freestanding

personal computer or a more powerful

computer it's really just the device

that's at the center of our Network

now usually we're going to do this with

some sort of professional setup

sometimes we'll have someone else come

in and sometimes we're going to do it

ourselves

now the network topography and design is

also pretty important we need to figure

out how we're going to set up the

network we talked about different

topographies previously so we probably

are going to want some sort of star

Network

if you recall what that is we might for

some reason have a ring if we have a

really intense local area network all

this is usually going to be used in a

Wan setting so really what we're going

to see usually is a star

and as you can see everything is

hardwired and this is a bird's eye view

of how we're going to connect this

network

so you can see we see each device

plugged up we see where every device

plugs in for instance this printer plugs

up directly to Mike's PC so if you're

having a trouble problem with the

printer we know that actually the PC

could be the problem not necessarily

this chord here and so knowing where

everything is set up and how everything

is set up is really important as you go

forth and of course important before I

start to create a huge Network by the

way your network and your plan

probably a lot more complex than this

but try drawing out your network at home

and see if you can do it as well

now backups are extremely important when

I have especially Enterprise setup the

loss of data that can occur could take

us out of operating and if I'm talking

about a network that is running Bank

information or health care then I really

need to potentially stop or avoid this

critical loss of data so regular backups

are key now there are a lot of different

ways to do this and we'll talk about

specifically some of the difference

between an incremental backup

and a differential backup

disgusting a plus as well

but there are some other Surefire ways

that we want to do this first all users

on the networks need to be regularly

saving and backing up their own work

then we might want to have an outside

service also taking care of our backups

so I might want to have the backup going

out

to a cloud or to a Wan in this case I

probably have and this computer is

representing My Lan all of the

information going to a central service

and then going out if I have a server

and all of the devices are hooked up

to the server then they're going to feed

the server with the information once

that information is on the server then I

can make sure that battle goes out to

the cloud the important thing is to

centralize where your information is

being saved if I have for instance data

being saved to

various computers and those computers

don't have a central place to store all

the data then backing up simply the

server is not going to do it a map to go

back up every individual computer and

that really doesn't work so what we

really want to have is a centralized

backup system and sometimes we want to

have redundancy

in this system

by not only backing it up locally but

backing it up out to the WAN or

alternatively having tapes that we're

going to take off site in case God

forbid something happened to my backup

plan

now it's also important that we document

our Network and once we've documented it

we need to continually audit where our

Network's weaknesses and strengths are

so I want to keep track of everything

that's on the network including the

hardware the software

diagrams that we have numbers serial

numbers Etc we also need to audit the

network for security strengths and

weaknesses we might do this by using a

port scanner

by having some sort of centralized virus

scan program like we'll see in a minute

and maybe even by hiring an outside

security firm to try to hack into my

system so I can see where the weaknesses

and strengths are

all this information is going to be key

in recovering

in case of major data loss

and that's the reason I want to always

just keep a nice long paper trail

sometimes you might want to print this

stuff off too because again the computer

goes down I can't access anything that's

digital or throw it up in the cloud then

I don't have to worry about it

now when we kept the management and

troubleshooting we always want to make

sure the network is running smoothly and

since you're the administrator you're

the person who has to be monitoring and

managing everything that's going on now

when there are issues you want to

troubleshoot and solve the issues where

they arise using the OSI model can be

really helpful in this case because you

can determine where the issue is

occurring for instance if I'm having a

trouble getting out to a certain website

but everyone seems to be getting out to

information then maybe the DNS is the

problem if for instance new devices

can't get on the network but if I

manually assign them an IP address it

does work well then probably my DHCP

server is is getting funky again this is

just an overview we're going to talk

about all this in more specifics as we

go forward

so I need to take a look at what the

error is figure out what the problem is

and get to the root issue especially

because what I'm really going for here

is what's called five nines which means

I want to be up

99.999 of the time

that's like five minutes of downtime per

year that five minutes however can be

really a big issue this also means I

want to be updating with Windows updates

and I want to be providing as much

information as possible to my network

and my network staff and even the

individuals who are using the network as

possible

finally when it comes to security and

virus protection I want to make sure to

audit and protect prevent the attacks

before they can happen so I'm going to

audit it and once I audit I can see what

sort of the issues are if I notice that

there's no Virus Protection Program then

I'm going to want to use some antivirus

software if I notice that there are open

ports getting out to the server through

the firewall then I'm going to want to

use that if I notice there isn't a

firewall I'm going to want to have to

put a firewall up so basically all the

things I can do there's no one size fits

all practice what you really have to do

is use the skills that you have in order

to audit the system and then prevent the

attacks before they happen using a

number of different tools might even use

something called an IPS or IDs which

would be uh

intrusion protection or intrusion

detection service or scanner

all right so just to go back over this

it was a very broad overview of what a

local area network is and some of the

things that we need to do in setting up

maintaining a land including creating

and having a network plan performing

regular backups providing documentation

keeping holding on to that documentation

auditing our Network to identify

weaknesses which is the main reason for

an audit we also might want to use the

audit to

identify bottlenecks or slow issues that

are going to cause speed issues

so on and then of course having proper

security such as virus scan programs

intrusion detection prevention systems

firewalls and so on we're going to talk

all about this and more in the coming

lessons but this was just a broad

overview to get a sort of set up

[Music]

thank you

local area networks switching

so in the last module we talked about

local area networks in general what they

do how we set them up how we administer

them but in order to have a functioning

local area network one of the most

important developments that we had was

called switching if you recall earlier

on we talked about the OSI model and if

you recall the OSI model went from level

one all the way up to level seven

now level one was the physical layer and

on there we talked briefly about a

device called a hub

now the problem with the Hub was

whenever data

went from one computer into the Hub

The Hub spouted all of that data out

to all the other computers on the

network this created a lot of broadcast

traffic because the Hub itself worked on

the physical layer all it did was repeat

all of the bits that went into it out to

all the other devices

but now we have something and we've had

for quite a while a thing called a

switch and this allows for switching

which operates mostly on level two

of the OSI model which if you recall is

the

data link layer

switching allows us to have a fully

functioning local area network because

it allows devices to talk

using the MAC address or the physical

address of the computer

so in this module we're going to talk

more in depth about what a switch is

how a switch operates which I just

touched upon a bit and then I'm going to

talk about a couple Advanced switches

you need to know about for the network

plus exam these are the multi-layer

switch also called a layer 3 switch or a

Smart Switch

and then we're going to talk about a

Content switch which as the name implies

deals with the content in the packet not

just relaying the packet of data itself

so a switch is an extremely important

part of a functioning Network so let's

look for a minute about a light switch a

light switch essentially has two pieces

of wire attached to it if we look at

like so

I'll put the little switch right there

and when the switch is flipped in One

Direction the circuit is completed when

it's flipped the other way then the

circuit is sort of broken and so the

light turns off

in a way an ethernet switch follows the

same principle except it's not only

attached to one single wire and cable

but to many some switches can even have

upwards of 200 cables attached to them

now these ethernet switches are used to

connect many if not all of the devices

on network and it establishes a flow of

data between them

this switch like a light switch makes a

connection between two different cables

and allows the data to flow specifically

between those two devices

now Lan switches are used to send data

from a single device to another

sometimes uh the and sometimes even

multiple devices there are devices as I

said called hubs but these do something

different

so what the switch really does here is

it allows data sent from one device to

go specifically

to the other device that it's meant for

and it does this

because it knows the MAC address

that it wants to send to now it doesn't

necessarily know where that Mac address

is on the network all it knows and it

puts this into the packet remember we

talked about that it puts it into the

header of the packet

the address which would be sort of like

the phone number or the social security

number of the computer that wants to

receive the data the switch then has a

table that says in each port

so if we had Port 1 2 3 4 and 5 it would

say

the MAC address connected to each port

and so when Port 1 sends data meant for

a MAC address

it knows oh I'm going to send that to

Port 5.

now it could also do this for multiple

for instance I'm going to send it to

Port 2 and port 5.

the key difference here as I pointed out

in the very first slide was rather than

a hub

which broadcasts out

to all devices

the switch creates a single switch

between two specific devices and closes

a connection

what this does in effect therefore is

reduce broadcast traffic and allow the

network to run much more efficiently

than a hub allowed

now there was a time when networking

devices only served one purpose and

their functions were specific to that

type of device but over years things

have evolved so now devices can do

multiple things now we see this

multi-layer switch or what you might

also see as a layer three switch or a

Smart Switch

what it does is it is not only a switch

it's also a router this is the reason

why it's called a layer 3 switch I

brought up the OSI model on the very

first slide

layer 1 physical

layer 2 data link

and if you recall layer three let's use

our mnemonic device please do not throw

sausage pizza away so this is the

network layer

if you recall we mentioned briefly that

routers which we'll talk about in more

depth later

operate on layer three that's because

IP addresses operate on layer three so a

switch can not only look at the MAC

address

but a multi-layer switch one that

operates not only in Layer Two but also

on layer three

can also look at IP addresses

so because this switch operates as both

a router and a switch it can send

information between several different

networks so here for instance I have

Network a and network B and let's see

this PC wants to talk with the server

on network B in the old system uh unless

network uh unless the server was

actually connected directly to the

switch there would be no way for the two

networks to sort of speak to one another

but because we have a device here

that's perhaps operating as a switch and

a router

it can route the data onto a different

network using an IP address

in some ways you could think about this

as the Advent of the area code

when we had a phone number

which was only

five digits or uh sorry seven digits

such as

um seven two three

five four one one we could talk to

anyone within our local network if we

knew

this number when we added the area code

we were allowed to then dial out to

other states and then we were allowed by

putting an international code to dial

out to different countries so we're

allowed to go then outside of our

specific Network in this way we're not

just dealing with Mac addresses we're

dealing with IP addresses and as we've

talked about IP addresses

are assigned by for instance a DHCP

server and so as a result they're more

temporary they're not hardwired onto the

device and it not only allows for

routing but it makes it a little more

complex to figure out where a device is

at any one time we'll talk more about

that in the next module the important

thing here to realize though is that a

multi-layer switch operates both as a

router

and as a switch because it works on

layer 3 and layer 2 which means it not

only reads

Mac addresses

but also IP addresses

now the next type of switch I want to

mention is something called a Content

switch the name content should give away

what we're about to talk about here now

these are not really used as much as we

see in today's networks because they're

quite costly but a Content switch will

actually analyze the data it receives

and forward it based on its content only

so rather than dealing with simply an IP

address or Mac address it actually looks

at what's inside

of the of the packet if we have a MAC

address here and then we put an IP

address on the outside of that in order

to tell where to go it's actually going

to look inside and look at the data and

determine where that content is going to

go

these switches are also sometimes called

load bearing switches

because they can evenly distribute data

based on the type of data there is in

the appropriate destinations which can

alleviate stress on a single server or

device

so for instance if I erase all this for

a second let's say we have

for some reason and let's say we have a

router right here which allows us to

connect out to the internet and then

information comes in straight from the

router to the content switch and we

don't know where the information is set

for or let's say we have

six different clients or servers it

doesn't really matter that each could

operate under the same sort of IP

address for instance we're going to put

them all together or group them the

content switch can say which one it's

going to go to based on the type of

information it's receiving so for

instance email is probably going to go

to one computer whereas web is going to

go to another whereas the FTP might go

to another and the packet itself doesn't

have to know which computer it's going

to the packet just has to have an IP

address and or Mac address and then the

contents which itself based on the

content is going to send that over

another way to think about this is if

I'm dealing with some sort of firewall

and I want the firewall to put certain

types of data into a

um

filtered

area

that needs to be scanned for viruses so

this is really going to help me

alleviate uh certain processes

and also help keep my network safer and

we'll talk about other devices that do

this as well

but when we're dealing with the content

we're dealing with further up on the OSI

model so we're not just dealing with

layer one or two or three even we might

even be dealing with layer four to some

extent

so just to recap we first talked about

what a switch is a switch again allows

for a direct connection

between

two devices

or more

the important thing to hear to realize

is that the devices communicate directly

because the switch creates a circuit

between those two devices Within

a box based on ports

now how it does this is it creates a

table

defining which ports are connected

to which Mac addresses again a MAC

address is the physical address that's

built into a device when it's made

this is different from a hub which just

broadcasts everything so if we were to

create an analogy we could say broadcast

which would mean all the data going out

to every other device

is

to a hub

what unicast

or multicast

is

to a switch

we also looked at some Advanced switches

you need to know about the first is a

multi-layer switch which operates on

layer 2 and 3. our usual switch because

it's only dealing with Mac addresses is

dealing with the data link layer

which on the OSI model

is Layer Two

a multi-layer switch is also operating

on layer 3. it also routes

so it is not just a switch it's also a

router a Content switch is even going

further up the OSI model and analyzes

the content

in a packet

to determine

where to send it

this is also why it's called a load

bearing switch because it helps reduce

the load on a specific node by

sending the data out to several

different devices

that can all deal with the same content

in a device

now we're going to talk further about

routing in the next lesson

[Music]

spanning tree protocol

so what is spanning tree

it's defined by the IEEE

802.1d standard

and basically it allows switches to

communicate in order to prevent loops on

our switch Network

it runs a mathematical algorithm

it finds out on blocks which ports would

be the possible causes of layer 2 loops

basically a loop will occur on our

switch Network when there's more than

one path for a frame to take

and this could cause obviously confusion

as I'll illustrate in a moment so it's a

real simple

illustration here with our diagram

so switch one for example will receive a

frame on its fast ethernet zero slash

one

and it will flood it out of its next

interface fast ethernet zero slash two

and remember if there's 24 interfaces

then it would be flooded in them out of

all 24.

now switch 2 would receive this

um and the address

would be for host a and it would be

firstly received by switch a switch one

and recognize that host a was connected

to fast ethernet 0.1 unfortunately that

address would come out of the bottom of

switch one go around and reach the

bottom of switch two switch two then

thinks that

it knows the way to get to host a and

the direction to go is through fast

ethernet zero slash one it will send

that out of fast ethernet uh sorry first

ethernet 0-2 and it will send that to

zero slash one now we have a problem in

that the ports on the switch all think

that they can release reach host a and

that isn't in fact the case

now there's no time to live field in

layer 2 frames so that would go around

around the network until every single

switch thinks it knows how to get to

host a

and it would bring your network to a

grinding halt

so there's a mathematical algorithm was

created

and it's based on two key components the

bridge ID

for bridge ID you can basically read

switch ID it's the same thing and the

path cost

so these are contained inside the frame

Bridge ideas and eight byte field

consisting of the bridge priority and

the MAC address the base Mac address of

the switch

the default Bridge priority is 32768

and then this is added to the MAC

address now I've issued a show version

on a switch and it showed the base Mac

address among other information and each

one will be different

so the path cost is used to calculate

the proximity to neighbor switches the

higher the bandwidth the lower the

default cost so we can see the 10

gigabit connection here has got the

lowest forecast allocated to it

so there's a four-step path selection

process

so the lowest route to bridge ID the

lowest path cost to the root Bridge

the lowest sender Bridge ID

and the lowest Port ID and it will go

through this four steps until it makes a

decision

this all happens after the exchange of

bridge protocol data units which are

called bpdus

so let's have a look at our diagram we

have three switches here and just to

keep things simple we've given them the

Mac addresses of all A's or B's and all

C's

they're all connected so we could

possibly have a loop here unless

something is done to close down one or

more of the ports

so there's a root Bridge election

firstly

then there's root Port selection

then there's a designated Port election

the bridge with the lowest Bridge ID is

selected as a route and remember it's a

combination between the priority and the

MAC address in this case the lowest Mac

address is going to be the one with all

of the A's because that's a lower number

in hexadecimal

so root Port is the port closest to the

root bridge now the route bridge will

not have any root ports because it is

the route Bridge so its ports will all

be known as designated ports you can see

switch two and three has elected its

closest port to the uh route Bridge as

fast ethernet zero slash one

every bridge you set the root Bridge

must elect the root ports and each

interface adds a cost

so as it goes as the frame goes through

different interfaces the cost is added

you can see fast ethernet 0 1 is 19. as

it gets to fast ethernet 0 2. that Port

cost is added again and 19 plus 19 costs

have been 19 each uh comes up as 38. so

fast ethernet 0 1 wins

the designated Port election and

designated report sends it receives

traffic on the segment to the root

Bridge

only one designated Port per segment you

can see there's a segment at the bottom

here

if I see Zero slash two on switch two

and three

the toy goes to the lowest root Bridge

ID lowest root path cost lowest sender

Bridge ID and lowest Port ID

and you can see on switch two and three

the lowest out of the two would be the

switch with the number MAC address bb bb

and so on

the port States for STP can only be one

of the five following it's forwarding

it's learning it's listening blocking or

disabled

all right so we've covered a fair bit

there I only wanted to give you a taster

STP and um there could be a lab on this

I haven't decided yet obviously you'll

be digging into a lot more detail when

you actually come to do the CCNA thanks

for listening

[Music]

welcome to modulate lesson 2B power over

ethernet

or Poe

what is poe the benefits components

the power supply equipment we love our

abbreviations there PSE

n-span mid span

power devices

modes in Poe standards how does it work

what is it first

Poe is a technology that allows a um a

device connected to an ethernet cable to

receive the following electrical power

and data

now obviously a device connected to an

ether cable was already going to be

receiving data because that's what um

ethernet was designed for

however what it wasn't initially

designed for and some very clever people

[Music]

um found or realized away and tested it

is to deliver power

and it's got all sorts of uses we're

talking in the context of networking

however I recently bought a guitar

effects board that plugs into the back

of my amp using a ethernet cable and I

thought it was going to come with a

power supply but as soon as I plug the

ethernet cable in it actually powered up

the pedalboard

and the pedal board offers a whole bunch

of effects you can record about five

minutes of Music Loop it add other

tracks onto that Loop and a whole bunch

of stuff so um very clever technology

and it's got a multitude of purposes

and it's just one of those things when

it's invented you think why didn't

somebody think of that earlier

the power devices that support Poe only

operate from the piracies through the

ethernet cable obviously there's a

finite amount of charge or power that

you can push through the cable because

it's quite a thin strand of metal

but um obviously avoid the need for

additional electrical wiring are you

your power supply unit and all the wires

that come with that and as we all know

every single power device has got a

different

and socket a jack on it and it just

makes it very awkward to keep a track of

which is which and then obviously your

power supply can die making our lives a

misery

so what is it we're supplying electrical

power through the electrical ethernet

cable in order to power devices I know

I'm stating the obvious here

and of course is uh designed for

beginners as well very handy for voice

over IP uh telephony very useful indeed

because it just um saves those extra

wires and cables

wireless access points network cameras

um very big in the field of security

especially industrial security and shops

and warehouses

since the devices can consume the

required power from the ethernet cable

there's no need for the separate local

power supply

if the device is an outdoor wireless

access point or a WAP it supports then

we can do the following we can send it

electrical power and we can send data

through the cable

eliminates the local power source

it's saving you money no great no need

to upgrade the existing CAT5 or coccyx

cabling which is another Lifesaver and a

wallet saver for companies no need to

purchase the power outlets electrical

wiring

I'm not sure if I'd talk about that in a

moment as well but it's just another

thing uh that that wouldn't possibly go

wrong I can't remember if I've put this

in a slide somewhere so you've got one

less

um point of failure there

very easy to install basically you just

plug it plug and play you can install it

even though locations that are hard to

reach because there's no need for local

power

increase reliability

um less risk of power interruptions

caused by human interference because the

device is essentially powered a lot of

the time our networking equipment has a

redundant power supplies as well and

backup generators especially if it's an

ISP

so they'll keep working

enhanced Operational Support and

monitoring and Remote Management we can

do through SNMP so we can power the

devices and perform different operations

over the network

very handy I know I could remotely

reboot different devices on my remote

rack

um if I couldn't reach it and I didn't

want to pay a tech to go and power cycle

stuff I could just send a message for

the power unit to reboot if it needed to

all right two basic components your

power supply equipment and your powered

device

your PSE is the a unit that adds

electrical power to the ethernet cable

you've got n Span and mid span

the end span is it refers to a switch

that supports Poe in addition to its

switching role so we can do both these

switches are capable of sending

electrical power and data to the device

mid-span refers to a standalone inline

injector that provides power to the

Ethernet cable so it's not built into a

switch

this is a situations where a switch

doesn't have the built-in Poe it could

be an older model or a cheaper model for

whatever reason

so you can pass the data coming from the

switch to the inline injector and can

output the same data but it adds power

to the um

points of the cable there

the power device supports Poe receives

the power via an ethernet cable

now in Poe there's two different modes

for combining the following data and

power of the ethernet cable the two

modes are not very imaginative

unfortunately mode a and mode B

suppose it could have been one or two or

Jack and Jill

mode a the electrical power and the data

are combined on the same wires over the

ethernet cable

this is called Phantom powering

mode B the electrical power and data are

carried on different wires which is more

common

separate the data and power inside the

ethernet cable

so in the internet cable if you've got a

pair of wires carried only the power

then the other pair of wires would carry

only the data

uh First International standard was

802.3 AF

ratified a long time ago June 2003 and

it defines um a power supply of up to

1.54 watts of DC

uses 48 volts

as growing demand for more power over

Ethernet cable so the standard was

updated and 802.3

Poe Plus

this was adopted back in 2009

and it defines the following a power

supply of up to 34.2 watts of DC power

using 48 volts

both the I um IEEE 802.3 AF and 80 are

now included in the ethernet standards

they've all been combined together

as we know from earlier presentations

the ethernet cable has four

pairs of Twisted wire

this is cart 5e and Cat6

uh for and we already covered earlier

that 10 base T and about um 100 base T

ethernet only use uh two pairs of wire

to send the data so this leaves us some

spare wires two pairs of spare wires

so electrical current flows in the loop

powering the electrical components such

as bulbs and fans the loop is an

electrical circuit

and since the electrical current flows

in the loop we need two conductors to

deliver power over an ethernet cable

uh typically we use 48 volts that says

sufficient power to transfer over the

cable and it's safe for users so it's

not going to injure anyone

now if you plug a Poe device into one

that isn't designed for use with Poe

then you could cause damage and fry it

and

in other words

and the PSE sends a lower voltage to a

device to detect the characteristic

signature of a compatible PD

if he takes a signature then it knows

the 48 volts can be applied

the PD lets the PSE know how much power

it requires to operate so this is to

save a surge basically on the

um line now too much power has been sent

the requirement of power is classified

in the power classes shown below

probably worth making a note of these

write them down just in case it comes up

in the exam

difference between the following power

supplied by the PSE power received by

the PD account for lostpower

now there is a maximum distance which

matches in with the ethernet standards

and maximum support distance is 100

meters

there's a new standard which increases

the power available and uses a wide

range of the following devices Thin

Client Terminals and pointer sales stuff

in shops

video conferencing

so I think that's all we need to know

we've covered Poe the benefits the

components the PSE end span mid-span the

power device the the modes for Poe

which is a and b uh the standards and

how does it work so that's all for now

thanks for watching

[Music]

local area Networks routing

so in the previous module we discussed

switches and as you remember they're

very important for the functionality of

a local area network

now when we talk about connecting

several different local area networks

together through

the internet we have to deal with how a

switch which again

is based on Mac addresses the physical

address on a computer

can find the MAC address of a computer

halfway across

the world

and the way it does this is by assigning

each Mac address uh an IP address

now when we start dealing with IP

address we deal with a completely

different type of device one which is

called routing and the process of

routing is what really allows the

internet to work and so in this module

we're going to talk more about the

devices that allow routing to work

called routers

so first of all we're going to Define

what a router is and then we're going to

talk about how it functions which is

also called routing

then we're going to identify something

called static routing just like we've

talked about dynamic

versus static IP addresses

we also have

Dynamic and static routing obviously one

is more resilient than the other but

there are certain instances in which we

want to always go to the same location

and that's why we're going to have

static routing then we need to cover

some terms that you might see when

you're dealing with routing these terms

are hop counts

costs

latency

and convergence so we're going to cover

all those terms so you have a good idea

in case you see them on the exam what

they're referring to

so a router is essentially like an

extension cable an extension cable

connects two sources of power and in

this case a router connects to networks

together in order to make a larger

Network

in networking the router is used to

connect two networks together and give a

clear route for data to travel between

these two devices now in smaller

settings such as houses or a small

office home office or Soho

the router connects the device is to the

Internet so for instance you have uh

your computer and you have a laptop and

perhaps you have some sort of Apple TV

device or some device that's connecting

to your TV and the internet and all of

these connect through what you call your

router

now this Soho router is actually doing

several things it's not just a router

but one of the things that it does is it

allows you to connect all of these

devices in your internal Network

otherwise known as your Lan out to the

large Wan or wide area network that

exists in the world this is called the

internet

so in a larger scale environment the

routers are used to make bigger Network

pieces so if you can imagine that

instead of just having my own home I

have say a number of buildings across a

city or a number of buildings across the

world and I want them all to talk to one

another and be able to locate one

another as though they're sitting right

next to each other this is where routers

are going to come into play

this is also why routers do a lot more

and are more expensive than switches

it's also why we need fewer of them

now in modern networking the router is

either going to be a dedicated device or

it could be a server

with a routing functionality

meaning it's a large computer with two

or more network cards or Nicks in it so

that you can have traffic going in and

then traffic going out

now when a router receives a packet of

data from a client device it reads the

information in the packets header and

determines what the destination of the

packet is after it finds out what the

destination address is it looks at a

routing table

in the router in order to determine

where the packet is going to go in its

next route so for instance let's say

this PC here which for sake of ease

we'll call pc1 wants to talk to PC2

now it has an IP address in mind and so

what it does is it goes perhaps through

a switch but eventually to the router at

the end of its LAN

and it says hey I'm looking for this

specific PC now this router has what's

called a routing table which sometimes

we're going to call an ARP table because

ARP again the address resolution

protocol is what allows routing to occur

it's this protocol that we've talked

about which allows for a table that

would say for instance one goes to IP

address 192 whatever whatever Etc

and so this router would look for this

information if it doesn't know it it's

going to say I don't know it but I'm

going to go to the next router that

might goes to this router and the second

router says oh yeah I know where that

computer is

and then can forward the packet onto the

computer

it also tells this router the first one

which we'll call let's say router a and

router B

where that destination was so it can add

it to its ARP or routing table

and if you imagine this is only what we

call one hop

because there is one hop between these

two routers but you can imagine in the

entire world if I'm traveling from say

here in New York City all the way to

Australia for instance I might have to

take several different Hops and also if

you imagine there are probably many

different routes that I can take to get

to a specific computer

if we imagine

that the circles are the two computers

and the squares are the different types

of routers and we have them connected

like so

well there are a lot of different routes

that a packet can take to get from point

A

to point B and so we were allowed on WE

rely rather on routers to tell us which

path it's going to take it could take

this path

or it could take

this path and so on and so forth and so

uh depending on the number of hops and a

number of other things we'll talk about

in just a minute it'll determine where

the packet needs to go in order to get

from point A to point B some other

things it's going to determine too or

what if there's a cut in the line well

now it can't get here

and so instead it'll say well let's try

one of our alternate routes as well

now in the previous slide I talked about

how routers might talk to one another in

order to automatically update their

routing tables this way two routers

always know how to communicate with each

other or one computer on one side of the

world can always get routed or the

information sent from one computer on

one side of the world can always get

routed to the information on another

side of the world

but in some instances we want to tell a

router exactly where to send information

destined for a specific Network now it

might not always be the most practical

way but sometimes it's necessary so

static routing is when a routes and

routing information are entered into

routing tables manually and this can be

time consuming and because it's prone to

human error it can be error written and

can cause some problems so this is why

it's only done on very small systems or

on ones that are very internal and

controlled

now in order to statically add a route

we're usually going to use something

called the route add command now this is

the sort of thing you might use if you

were adding a route to a Cisco router or

to a Windows machine for instance that

was acting as a router or even a Windows

machine that's at the edge of a network

and needs to go out to another the way

it works is we use the route add command

with the network name

The Mask or the subnet mask

and the IP address of the Gateway

so this tells us if we want to get to

the network 192.168.2.1

we need to go to the subnet mask

255.255.0

and the Gateway

192.168.2.4 now all this information

would automatically be done uh

dynamically by most routers but in some

cases we're going to want to add it or

statically now this isn't something of

necessarily seen come up on the network

plus exam but I did want to clarify it

and go over it just briefly in case you

ever saw it in the field since this

might be something to do something that

your administrator or your boss asks you

to do for whatever reason or maybe

something you want to play around with

if you need more information

simply Google the route add command but

again I don't think you'll see it on the

network plus exam

finally I mentioned that there were some

important terms we had to mention when

we talk about routing the first is the

hop count this is the number of hops it

takes to reach a connection or before an

appropriate connection is made if you

remember when we used the trace route

command

remember that was trace route it went

through a number of hops or a number of

routers until it got from our computer

to for instance Googles so if our

computer and the destination computer

are represented by these two circles and

let's say we have our internal router so

for instance perhaps we are in a

10.0.0.xnetwork and then they're on

their own network as well

let's say that this is a for instance uh

124.68.24.3 Network

now we need to get from hours to theirs

and so let's say there are a number of

different routers in between well in

this case we have one two three four

five six hops between us and the

destination

so if there are an infinite number of

hops that means that the destination is

unreachable or that for some reason

we're getting caught into some sort of

loop

so the Hops keep coming back to itself

one another way that this can you can

see this as I erase this is for instance

we have

A system that looks something like

this and these are each routers

so what might happen

as I draw out all the connections

is the route might go from here one hop

to here and then instead of going to the

destination it simply goes like this

because

this could be a valid way of getting to

the router right we could hop here and

then we could go over there but instead

it hops and then this one sends it along

this route so we move here and basically

we create a loop in which the

destination is never reachable now this

could be because of some sort of poor uh

routing table and what you would need to

do is basically tell one of these

routers that the destination goes over

here

the next term is What's called the cost

this is the number of uh or these are

the numbers rather that are associated

with traveling from point A to point B

generally this means Hops and several

different links along the path the lower

number of of

hops the better we are so the cost would

be how many hops total we need to travel

from point A to point B generally

speaking we're going to look at the

lowest number of hops possible but there

are some instances in which we could

want to go more hops or have a higher

cost through hops in order to save on

something else for instance latency

latency is the time it takes from a

packet to go from one location to

another so to give you an example of

what I was just talking about sometimes

we go route specific

which means that it's going to choose

this route because this is only two hops

however

let's say

let's say that instead of traveling this

let's say this was a dial-up connection

right here

and this was a broadband connection

well obviously

even though we have to go one two three

four hops as opposed to three on this

one

we would want to take the four hops

because the latency is going to be less

and so the cost would be determined

based not only in hops but on latency as

well

now convergence is the process of

routers discovering the network

structure has changed in this way it

updates the routing tables to the

knowledge of the networks so for

instance

if we have two different paths that a

route could take

it could either go

like this or

like this we would want to know if one

of the connections had been severed and

then this routing table would be updated

to know don't go on this route instead

go on that route

the process of this happening

is called convergence

so although this module might have been

short and a brief overview of routing we

went over some key things first of all

we talked about a router this is the

device that generally allows us to

connect our Lan out to a Wan

it does this by operating on layer 3 of

The OSI model which again is responsible

for IP addresses as opposed to switches

which work with Mac addresses and

therefore operate on layer 2. we also

talked about how a router functions in

this case we talked about the fact that

a router has what's called a routing

table

which can sometimes be called an ARP

table

the ARP table

tells it where an IP address goes to get

to a specific place so it Maps basic IPS

to Mac addresses and then the routing

table would say how many routes you take

to get to a specific node on the network

we also looked at static routing which

is manually updating the routing table

so that way you can tell it where to go

we also talked about some key terms

including hop counts which would be like

the number of places we're going to go

if we're going to take a trip this would

be for instance the miles

we looked at the cost which basically

means we're going to take several things

into consideration when determining our

trip

for instance if one has a highway

whereas the other are a bunch of local

roads with stop lights

then even though it might be more miles

to go on the Highway we're going to go

there as opposed to this one with the

stop lights because we know we're

getting there faster

finally convergence is keeping all these

routing tables up to date

that way we know which route is the most

effective at any one time

in the next module I'm going to talk

more about how all this works in Dynamic

routing and the protocols that are

involved with it

[Music]

thank you

welcome to module 8 lesson 3A on routing

metrics or if you're in the UK routing

metrics

so this is a little bit esoteric in as

much as

you're better off configuring routing

and playing with this and doing Hands-On

labs which you don't do for the content

Network plus but if you're doing a CCNA

exam for Cisco for example you'd

actually have examples where you could

see this and been affected as you

configure the different routing

protocols and add more hops or other

devices

but we'll do our best we're going to

look at routing metrics the MTU

metric costs latency load reliability

so routing metrics and tables on a

router

and it's actually the same for servers

as well

and the writing table can contain a

field known as the metric

now a metric is a value and that value

can be made from a number of different

factors depending on the route the

routing protocol

this is used by the router when it runs

a mathematical algorithm to work out the

best path to get from a which will be

the local router 2B which is the remote

router

now I issue the show IP routes on a

router in the image here and I just

highlighted MD if you did look at the

table there is short for eigrp on Cisco

routing tables it'd be different if

you're using Juniper or a different

device but just for your information the

different numbers there are the routing

metrics the ergrp is calculated based

upon the location of the different

networks which are 34 uh

4.4.4.4 the 23 Network 24 and the 12

Network

don't worry too much about that but I

just wanted to show you that you can

actually see it in a routing table and

the number 90 before the

the routing metric there is the

administrative distance that um is is

allocated to the protocol and for ergrp

it's um 90 internally ergrp

so if a router has different routes to

the same network the routing metric

helps the router decide which of these

routes to choose because you could have

30 40 50 plus ways to get from A to B

and the writing table will just be too

big and the router would crash so it

uses the best path and inserts the best

path in the routing table

all right each writing protocol uses a

different metric I think you probably

need an overview just for the network

Plus

so we've got two routers a router one

and a router 11 between these two

routers you've got nine other routers

that connect to different Networks

and you can see the different routers

there path x y and z are the different

paths in order to get to router 11 and

of course you could make it more

complicated by connecting all of the

routers in between the paths which may

well be the case

so you want to get from router 1 to

router 11 and there's three different

paths to choose from

sake of convenience as I said x y and z

are the different path names writing

protocols will choose a route with the

lowest metric

now if we use rip routing information

protocol it only uses hop count it

doesn't care about the speed of the link

or if the Link's reliable or anything

like that it's

um a fairly old writing protocol and it

was built for quite small networks

because all networks were small at the

time

and so you can see there that there's uh

one path has got three hops one has got

one two three four hops in the middle if

you're not counting the um source and

destination the other has two routers

nine and ten so that's going to be the

shortest amount of hops

two hops four or three

so if rip chooses the route between

router 1 and 11 it will choose the best

path as path X

it's got the lowest top count

now I've introduced a problem here I've

actually shown you the speed of the

links and the speed of path X is only

56k

which is a crazy slow when you compare

it to path Y which is one Meg however

rip won't understand this now you can

configure it

and and do extra configurations to

um force it to take path y but by

default it um it won't it won't use path

y because the volt counts

so different routes and protocols use

different metrics and since the link

speed affects the throughput writing

protocols such as ergrp which is an

advanced writing protocol take into

account now it can take into account

Cisco's version of vrgrp only uses two

of the possible values

um that um are usable Within ergrp

and Cisco have their own version of

ergrp

now considering now ergb ergrp can

actually use five but we've only listed

the two used by Cisco devices here which

are bandwidth and delay

now considering the link speeds path Y

is better because we want to take the

faster

um route there

routine can be based on the following

factors the MTU

the costs cost latency administrative

distance shortest path bridging

uh the MTU

um is one factor as I've mentioned

stands for maximum transmission unit

this is the largest size of the packet

that can be transmitted across the link

without that packet being fragmented

fragmented means it gets chopped into

different sizes

and numbered sent and then reassembled

on the other side of the link and

obviously this can introduce the scope

for errors and obviously there's delay

while this fragmentation takes place

thank you also overhead involved because

of the acknowledgments each packet is

sent and received as it goes along and

it could be requested to be

re-transmitted also

largest packet you can send by an

Ethernet Network because of the way the

technology is designed is a 1500 byte

now cost I actually did an output here

of a router running ospf or an interface

running ospf here

and you can see the other information is

irrelevant for our purposes but the cost

has been allocated as 64. different

interface speeds are given different

costs by ospf

total cost so this link and the other

link and all the other links between and

the hosts are added up together and then

the best cast which is the lowest one is

installed into the routing table and the

other costs

um can be put into the topology table

for use if the best path goes down so

you can have second best third best and

so on

a router protocol can also use delay or

latency as a metric

delay refers to the delay of the links

across the route so is there any delays

to the packets been sent and received

a load I've actually issued a show

interfaces serial zero slash one on this

router and you can see some of the

metrics that are allocated

to this particular interface the mtus

1500 the bandwidth is 1544 so one Meg

delay and twenty thousand millisecs

a reliability 255 out of 255 is the best

it means um it's very reliable and that

if there's problems then the number goes

down like 10 out of two five five is

very bad

the transmission load is low it's the

lowest one out of two five five receive

load is one out of two five five

which is an arbitrary value

so load is the measure of traffic

consuming the links we don't want our

package to be traveling along a path

with high traffic

so the past with the lowest load would

be the best path if we're using load as

a metric of course

reliability is in there also which I've

discussed we want to take into

consideration the reliability of the

path

reliability metric has a value that

denotes a number of times any of the

following occurs the link goes down or

had errors at a certain period of time

the router protocol may use the

following one metric as in rip multiple

link characteristics to calculate a

metric for example ergrp which is

bandwidth and delay of the line

ergp uses characteristics to calculate a

metric for best path I've actually

done a output of a Cisco router here

for ergrp and you can see the different

metrics here some won't be used

you can actually affect this if you want

in the configuration normally best to

speak to a Cisco engineer before you do

this

so some of the delay characteristics are

delay bandwidth reliability load

and you can see others in there but

again it's bandwidth And Delay the line

is usually used

uh summary so far we've covered routing

metrics the MTU

metric costs uh latency load reliability

so that's all we need to know for now

thanks for watching

[Music]

welcome to module 8 lesson 3B routing

tables

another hard one to put in perspective

if we don't configure

live routers but we'll do our best we're

going to look at routing the routing

table

static routes and a static route example

and dynamic routing protocols only an

overview really and then an example and

physically connected Networks

so routing is the process of sending a

packet from a source Network to a

destination in another Network

we actually have to differentiate

between routing and packet switching

writing is a process where the router

actually decides the best route to get

from A to Z and then switching in the in

the context of sending IP packets is

actually pushing the packet out of the

correct interface I just want to do

highlight the difference between the two

and obviously we're looking at Network

plus level stuff here so there's two

aspects determining the optimal route

which is the routing part and then

pushing the packet through the network

which is the switching part

so routes are based on networks we don't

really

um

we don't want to concern ourselves with

host on networks because if you can

imagine even an Enterprise Network for

some large company could have thousands

of hosts

it'd be pointless every router having

thousands of hosts listed so what it

wants to do is focus on Networks

and then it will then switch the packet

to the correct Network and another

router and then finally the host address

in

the Mac part of the address will be

taken care of by the Lan switches

so a route is not based on the host

because the packets are routed through

the networks it doesn't use the physical

Mac address of the hosts

so here's the example we've got a a few

different I've shrunk down each switch

would have it could have a 12 or 24 host

connected but I've just added one and

you can see we've got three different

networks listed here the 192 a 10 and a

172 Network

so the MAC address of the destination

host is only used for the final delivery

so the switch if these are layer 2

switches which are my examples they are

it won't understand the IP

address portion of the packet because

we're looking inside the frame and it

will match the MAC address

to the correct port and then deliver the

frame to that particular Port this is

what our switches are concerned with

whereas all the routing between the

three routers in the diagram here

they're concerned with which network or

which Port which network is connected to

of the router

so the switch down here on the right if

you issue a show Mac address table on a

Cisco switch at least you'll see a map

in and you'll see which Mac address and

each one's unique is connected to which

physical ports and this particular one

they're all in the same VLAN because

we're not worried about

um into VLAN any any VLAN stuff here so

gigabit zero slash two zero slash two

zero slash two and fast ethernet zero

slash one if you see more than one host

connected to one port it means it's a

trunk and it's connected to another

switch somebody somewhere

so this switch down here would be

connected to another switch via a

gigabit Ethernet port and it's learned a

few host addresses that are connected to

that

all right so when we send packets out to

the internet the following is true the

routers have a database of routes stored

in a table called a routing table it

could actually be a database consisting

of one route or just connected routes

depends how we configure stuff really

the writers use this information in the

writing tables and they make a decision

based upon the next hop this is what

routers all do they send a packet to the

next hop

unless they are the the last hop in the

journey

so there's a routing table here you can

see uh there's a network been learned

and

if I just put the text here the routing

table contains the following the network

ID here the network is three zero zero

zero and it's actually found a host on

this network

destination Network address and subnet

mask I'm not sure how this is been

configured because I pulled this one off

the um off the internet you can actually

see at the bottom 10 10 23 0 is a

network found by ospf

and it will have the next top and

Gateway so if we go to the bottom 10 10

23 0 110 is the administrative distance

for rspf 20 is the cost

and it's been learned via the address 10

10 12.2 which will be another router

interface somewhere connected

it was actually learned one minute and

17 seconds ago via the fast ethernet 0 0

interface

all right so these the router has enough

information that if it wants to send any

packets to any host on the 10 10 23

Network it knows where to send it and it

also knows how fresh that route is

all right the metric metrics used to

decide which route is to be taken if if

multiple routes exist for a given

destination Network so we can see some

metrics here in fact

um squared in the yellow highlighting

you can see two routes have been learned

to the same network the reason is the

metric is exactly the same so it must be

exactly the same cost

to reach the destination via two

different IP addresses one seven two

twenty four one two two and one seven

two twenty four one three four so as

long as the costs are the same then

ergrp is configured to load balance over

those

I think with um Cisco ergrp

automatically load balances over up to

four links and you can change that value

up to 16. but this could change

depending on your platform

all right so the administrative distance

when a router's right running two roads

right on protocols such as rip and SPF

and everything else is equal

so for example rip and SPF it will use

the ad administrative distance to

determine which route to choose I've

configured uh two routers up here just

connected by a gigabit zero and zero

slash one

the top Network for the top link is 192.

the bot and it's using rip the bottom is

rspf and it's 172. and at the end we

have another Network a Ted Network that

is advertised via rip and ospf

so rip I know the administrative

distance is 120 ospf is 110 so routes to

get from router 0 to the 10 Network

should use ospf

and if the ospf network goes down or the

interface is really no SPF then the rip

Network could be chosen this is a part

of the output from a show ospf you can

see 120 is the ad one is how many hops

and under the 810 is the ad Slash 2 is

the cost because rspf uses a cost not a

hop value so it's the um the calculation

is used looking at the um speed of the

link is put into a formula

and each link between source and

destination is added to the cast so the

cost is only two which is the gigabit

Ethernet speed there

and it'll be the speed of the interface

that the 10 networks connected to

so if if I try and Trace traffic going

from router 0 to the 10 Network you can

see it's traced and it's used the next

hop address of

172.16.1.2 which is the gigabit uh zero

slash one of router one

and so that's basically the preferred

path if for some reason that path went

down it would start using the next best

a next best ad which is Rip

writing table writing information is

populated through a few different means

it can be a connected route actually a

static route I I suppose I said

connected there or a dynamic routing

protocol what you can figure depends on

your network if it's a tiny little

Network or if it's in a remote office

somewhere then you probably use a static

route to just send all traffic to the

next top router

so this is the show IP route and I've

highlighted in red the connected routes

for router 0.

it's a 17216 another 192.1681 network is

showing as C connected are in Cisco at

least that's for it oh stands for ospf

and L stands for local

static route is a route that is manually

added to a router by administrator

so you can see here router 1 on the left

has got a default static route

which you can recognize it because it's

all zeros

I'll give you an example in a moment if

router 1 receives traffic destined to

any network other than a local one are

you one that's connected it should

really know where to send that traffic

if there's no entry listed then it by

default routers will drop the packets

since R2 is the next hop for router want

to reach the internet what we can

basically do is put a static route on

router 1 saying send any traffic to any

network over to R2 and let R2 worry

about where to send it

when our one receives the traffic for a

network it's not available it will now

send it out of its interface using the

default static routes I've actually

configured a static route here on a

Cisco router

iprout000 and then zero zero zero zero

so any

and IP address

and any network go out to our gigabit

Ethernet interface instead of g00 I

could have put an IP address for the

next top router as long as the router

knows how to get there

and for the R2 you can do the same thing

you could have a static route as long as

you know your next hop which would be

your ISP router let your ISP take care

of any routing decisions

all right Dynamic routing practicals

this is a routing protocol that

dynamically builds routing information

such as the following the network the

next harp and it will build a topology

table and from the topology table it

will choose the best route to put in the

routing table and the topology table

can supply second third and fourth best

routes and so on

static routing does not do well in large

networks because you would have to

manually add 5 10 15 20 routes per

router

so you can imagine you're going to have

a lot of work there if you decide to

change the IP address and or even add

one device

so you don't want your routers to

automatically learn the routes update

any changes without you having to worry

about it and this is where routing

protocols make our life a lot easier

once you've configured which networks

you want to advertise then depending on

which protocol you're using

and the writing protocol will go ahead

and run on automatic settings unless you

change the settings for whatever reason

the routers use the router protocols to

learn about available routes to build a

routing table

and the routing protocol communicates

with the same router protocol on another

router you can't have rip on one router

communicating with rspf on the other

because they work in entirely different

ways and use different protocols and

ports

to um send their information

so this information is placed in the

writing table

so as an example here router one two and

three you've got some different networks

connected

a pc1's default gateway because PCS

won't do the routing will always be

router one you'll just send all traffic

to whatever the IP address is of the

router there normally in In fairness the

PC is connected to a switch and then a

router this is just a simplified diagram

so if router one has two routes to the

internet then it will choose the best

one depending on the routing protocol

unless you've changed the settings you

can obviously manipulate things

if rip has been used then it will choose

a hop count and it will choose the

lowest top count so it will be router 1

to router 3. even though it's

128k the link there

if rspf is being used

um then it will choose R2

that might not be correct actually if I

look at the diagram

you'd have to add up the um speed of the

links but the speed between router 2 and

router 3 is being put as 128k so um that

isn't quite correct say you've got a one

Meg link between router one and two and

then two and three then ospf should

choose the

um that link even though it's more hops

because it's only looking at the costs

so Dynamic router protocol also allows a

router to reroute around a fellow link

and this is where the topology table

will come in it will have a um ability

or most advanced protocols do to have

some backup routes in the topology table

that will quickly take over

uh physically connected networks routers

interfaces physically connected to a

network it obviously knows how to reach

that Network

since r1's interface is directly

connected to these networks it already

knows how to reach them

all right so we've covered routing just

in an overview the routing table

static routes an example of a static

route autonomic routing protocols as an

example and then physically connected

Networks

now your physically connected networks

you don't have to advertise but

obviously if you want traffic to be able

to reach that Network then you're going

to need to add a dynamic or static route

but that's all for now thanks for

watching

[Music]

local area networks Dynamic routing and

protocols

so in the previous module we discussed

what a router is and how it functions

and we discussed static routing which is

the process of manually creating a

routing table so in this module we're

going to Define in more depth

Dynamic routing which is what allows

routing just like with DHCP and IP

addresses to be dynamically up kept

which is going to allow for

a much more flexible Network now

although this title of this entire

lesson is local area networks in some

ways we could extend this to wide area

Networks so we're going to talk about

Dynamic routing and then we're going to

talk about two different types of

dynamic routing these are distant vector

and Link State now we sort of alluded to

the difference between these in the

previous module when I was discussing

Hops and simply relying on the number of

hops to get from one place to the other

versus looking at for instance if one

link was a dial-up or Broadband or if

the link was even shut down completely

and so there are two different types of

protocol sets we're going to look at

there are distant Vector protocols these

are the protocols that allow distant

Vector routing and then there are link

State protocols you'll see them listed

here and we'll talk about each one in

depth and if the acronyms are already

starting to freak you out don't worry

about it what we want to do is just know

which ones are distance vector and which

ones are link state so as you can tell

if you can remember that these two are

link State you'll be fine for the

network plus exam which again is

multiple choice and will ask you to

recognize it but we'll go over them in a

little more depth than that

so Dynamic routing uses a series of

protocols to establish the routing table

as opposed to the route add command all

of the routers pass information about

themselves along to the other routers

and they use this information to

establish a routing table based on

certain specifics of the other routers

now there are two different types of

protocols that are used like I just

mentioned there are the distance Vector

protocols which in some ways are older

and the link State protocols

which are newer the reason being that

distance vector

looks just at the number of miles we

have to travel and the link state

also looks at the traffic so it can tell

us if although we'll have to go further

miles it's going to be quicker based on

traffic just like our GPS system

so

let's talk about distance Vector first

in distance Vector routing the routers

on the network are only aware of the

routers that they are directly connected

to so if this is one router let's call

this router one

and there's a router two

a router three

and a router four router 1 is only aware

of routers two and three so these

routers don't know anything about the

rest of the routers on the network

unless of course they're directly linked

now they can share route information

with these directly connected routers

but the flow of communication is limited

as a result the spaces between distance

Vector routers are known as we just

talked about this

hops now each router along these paths

represent a hop for example a network

with a five distance Vector routers has

four hops from the first to last router

if we have one two three four five

routers

there's one two three

four hops

it's also important to notice that

convergence that's the updating of all

of the information to the router table

is going to take longer with this set of

protocols than with link state which

we'll look at in a second this is

because the routers don't have the

knowledge of the entire network so it

takes longer for them to become aware of

a change in the network

so there are four main distance Vector

protocols that are still in use today

the first one is called the routing

information protocol or rip

routing information protocol version 2

there's the Border Gateway protocol or

bgp and finally the enhanced interior

Gateway routing protocol or eigrp you

see how these two sort of have some

similar

names in them and these two are

obviously related

rip or routing information protocol is

limited to only 15 hops

originally it required the information

that updated every 30 seconds

and on a small Network this wouldn't

have been a problem but if we're talking

about a very large Network which is

where networks went there was going to

be a large amount of traffic being sent

between routers at any one time and so

this became not very useful because of

speed and also the protocol itself was

just not very secure and it was very

vulnerable to attacks and it didn't

support authentication of any sort now

remember we want something like

authentication which would be a username

and a password so I can make sure the

router contacted me is the one that I

wanted to talk with so

rip 2 came out and this featured

authentication so it added it for better

security

and it also was designed to reduce

traffic flow

but it only supported 15 hops because it

had to be backwards compatible with the

previous version and since the previous

version was only 15 hops so was this one

so again not very useful for very large

intense networks such as the internet

now bgp is often associated with the

internet and the reason is because it

can be used between internet gateway

hosts as this name

implies

so it examines the routing table and

decides what is the best route for data

to travel based on the connections the

distances and certain addresses

now the enhanced interior Gateway

routing protocol are eigrp draws upon

information that its neighboring routers

have

so it would look at all the routers

that it's a neighbor with now route is

configured with eigrp would use that

information to determine the best path

for data all determined by what all

these other routers know so that's one

of the benefits is it went outside of

itself

so here's an example of basically

distance Vector routing the router on

the top left over here

has no idea what's going on

with the routers over here

it can only make a routing table based

on the routers it's connected to just

like the one on the right can only make

uh

routing table based on the routers it's

connected to

therefore these two are unaware of each

other's dis of each other's

existence because they're not connected

to each other

now of course they can still communicate

because there's probably a router some

place that one of these is connected to

that will connect them but you can see

how this is going to make for a lot less

efficient routing

so unlike those distance Vector routers

routers configured with link State

Protocols are aware of every other

router on the entire network they use

each other to build an enormous Network

map

and then this network Mac is shared with

each other unlike distance Vector link

State routers will update with less

frequency so there's less traffic on the

network

now if a change in the Network's

topography occurs then they

automatically update with each other and

share the map with each other so instead

of Simply updating at a certain interval

of time they're going to update whenever

there's a change

now though this seems like link state

has a better set of protocols link State

routers also require a more powerful

system components such as better Ram

cetera then distance vector and that's

why we still see distance Vector used

quite a bit in some cases we don't need

link state

so it offers quicker convergence

as a result of this automatically

updating but this also means it needs

more power

so there are two protocols I want to go

over with this the first is

the open shortest path first or ospf and

the second is the intermediate system to

intermediate system protocol these are

really similar and they both use a

shortest path algorithm

to determine the shortest way for the

data to travel however we're generally

going to see this one the OS PF on

medium networks and Isis

on larger Networks

another benefit of this is because it

knows all of the routers on the network

it doesn't just think about distance it

also looks at what type of connections

we have it looks at the state of the

links and therefore it can make give you

in some cases the best route available

not just based on the number of hops but

on a lot of different factors so here we

can see what a link State protocol might

look like the two different groups

aren't connected directly however

they're both aware of the entire network

layout as you can see if we imagine that

this was a map inside of the router and

then they can then share that Network

layout with all of their other routers

in this way they create a massive

Network

and massive routing map on their Network

and can communicate much more

efficiently and quickly

so we've just talked about Dynamic

routing which means basically that the

routers

builds

their own network map

or routing table

this is much more efficient than static

routing we also compare distance Vector

to link State again distance Vector is

focused very much on Hops and isn't

aware of all of the devices on the

network only direct connections

link State on the other hand

looks at other features

so for instance traffic latency Etc

and has a huge Network map

of course the downside is that distance

Vector is going to be a lot more

efficient with the resources it has in

the router than link state which

requires uh perhaps better or more

powerful system components

we also finally talked about the

different protocols rip rip version 2

bgp and eigrp were our disinspectors and

our two link States again ospf is for

medium Networks

and Isis

or Isis is for larger Networks

we still see all of these used

but these are newer

perhaps a faster at convergence

although perhaps not the most ideal for

our Network or necessary for the network

we have

so now that we've talked about switching

and routing I want to talk about

something which is a little not so much

complex but allows for more organization

within our Network which is called vlans

or virtual lands

[Music]

welcome to module 8 lesson 4A igp and

EGP

all right so we're going to look uh this

is an overview really to put things in

context a dynamic router protocols

interior Gateway protocols autonomous

systems

bgp in brief obviously how the protocol

works much

so we can classify Dynamic writing

protocols into interior uh and exterior

the interior protocols these are the

ones that we'll be using mostly As

Network Engineers on a day-to-day basis

unless we end up working for an ISP an

internet service provider

so in order to understand what we mean

by the inside of a network we actually

need to understand the term autonomous

system which we generally shorten as an

m2as

so an AES is one or more networks that

are governed by a single Administration

so it could be a company Network or a

large company Network and you can see

here we have um three different asses

now these as could actually all belong

to the same company and inside you've

got a different administrative domains

for example the large Cloud as200 could

all be running ospf and you could have

bought a company on the top left there

that um is running ergrp or just has a

different set of administrative

principle principles and roles in this

particular example you can see as100 on

the top left and as300 on the top right

are actually isps

these are internet service providers

so

um even though it says here that the as

within is under the control of a single

Authority you could have various teams

managing different parts of the network

however it's all under the same

administrative control

as is actually defined in the one of the

rfcs 1930 if you wanted to Google that

but it'd probably be a fairly long and

boring read I think

according to the definition of the as

it's a set of routers under a single

technical Administration uses an igp

interior Gateway protocol and common

metrics to Route packets within the as

you would you generally use an exterior

Gateway protocol an EGP to Route package

to other autonomous systems

The ROC says that the as a single and

clearly defined routing policy which

makes sense if your company is running

the administration

now routers within an AES use an igp

which I've already said so here's um

an image from Microsoft's tech net you

can see there's two different autonomous

systems here they're running an igp and

is here we Gateway protocol doing all

their ospf routing whatever they need to

do and then in order to communicate with

another autonomous system it's running

in the EGP between the two border

routers there

you can further and divide igps into

distance Vector link state or hybrid

some of the common ones are rip or rip

version two

ospf is an advanced writing protocol

Isis

ergrp is a hybrid which is uses parts of

the distance vector and part of the link

state igrp is um

pretty redundant now to be honest it's

not very rarely used because of its

aging it's not very flexible at all

uh exterior Gateway protocol is a

routing protocol used to route between a

s's which we've already mentioned if

you're going to route between autonomous

systems it's referred to as inter as

routing

so an example is bgp which is mentioned

in the syllabus is used for inter as

routing so it's a route between

as1 2 and 3 here we've got an exterior

Gateway routing protocol there is

actually a writing protocol called

interior bgp which you can use to Route

within an autonomous system and I think

that's mentioned in the syllabus in any

detail but um bgp is used to route

between autonomous systems exterior bgp

now each as is actually given a unique

number you have to apply for these

numbers to your service provider or your

internet registry whoever that may be

and as I said I've already said this it

needs to be a unique Asm

and the ASN is a actually supplied by

the internet assigned numbers Authority

and they'll split the numbers between

whoever governs the numbers within your

country

uh all organizations within the network

don't need ASN the Network that has a

single connection to an ISP and a single

prefix

which is a subnet mask doesn't need the

ASM because the prefix of that network

is managed by the internet service

provider so you may not actually need to

worry about any of the exterior routing

you could be really low SPF all through

your network send your traffic to your

internet service provider and let that

let them take care of any exterior

routing

bgp exterior Gateway protocol and it

routes packets between the Asus which

I've already said here is an example of

some different ases and on the bottom

you've got as1

which has the um prefix

192.020 and the subnet mask of Slash 24.

24 bits

according to the RFC and bgp is an

inter-autonomous system router protocol

it actually uses TCP so it uses a

reliable transport method as opposed to

other protocols it listens on TC Port

what TCP Port 179

and you can see we've caught a captured

a bgp message with a a packet capture

program looks like Wireshark there's an

open message and you can see the

destination Port there is 179 and it's

using TCP

current version is four if you could

look further down inside the bgp packet

it says version four

that's the current version in use today

all right so CompTIA they actually list

it as a hybrid protocol I'm not sure why

they do that

it's a path Vector routing protocol

so you can see the paths here as1 at the

bottom is sending the nlris network

layer reachability information I.E how

to get to that particular Network and

prefix

router 3 appends its path which is as3

and then when the

um

network

192020 is sent to as5 it's appended with

the paths four three and one

as a reply is sent the different paths

are removed so as4 will remove path four

and send it to three we'll remove three

and back over to one

all right so we've covered an overview

of dynamic protocols interior routing

protocols what an as is bgp that's all

for now thanks for watching

[Music]

log into module 8 lesson 4B routing

loops

but look at what a writing loop is and

distance Vector writing protocols

splitter Eisen and poison reverse which

are there a couple of the solutions to

prevent

routing loops on a network layer 3 loops

so writing Loop is a network problem

where a pucky gets routed between two or

more routers endlessly

now this is a different solution to

layer 2 Loops where we have a spanning

tree protocol

and some Advanced versions of that that

uh there to stop layer 2 packet

circulated because Layer Two packets

don't have a time to live value

so this happens when the writing table

has incorrect information

as we know during the writing process

routers forward packets to various

destinations these are based on the

entries in the routing table now if one

of these entries is incorrect for

example a network goes down

then a routing Loop can occur so here's

an example I'll go into more detail in a

bit but for today's advertising

192.168.20 which advertises out of both

interfaces there it goes to router BM

router C both of which advertise to

router a

now rights array unfortunately has two

ways to send the packet to router

um or to to paths to see

uh 192.16820 which isn't necessarily a

problem however what router a does

advertised the fact that it knows how to

get to that Network to router C to

router B which then forwards it to

router D now router D is hearing from

other routers that they know or they

have a route to get to 192.1682.0

now if that Network goes down router d

will be sending packets to that Network

either to router C or router B because

it's heard from those routers that it

knows how to reach that Network

so this is how our writing Loop can

um cause havoc on your network

so go go to a bit more detail with

another example here obviously have a

detrimental effect

increases packet loss utilization of the

links CPU utilization on your routers

because it has to process

every time the packet's received

so in distance Vector protocols slow

convergence causes routing Loops this is

when other parts of the network are

stabilizing their routing tables slower

than other parts of the network

any change in the network is updated in

the writing tables

so during the process the routing tables

have inconsistent entries due to slow

convergence this could be due to

bandwidth or pros and processing speeds

on your router

the network is said to have converged

when all writing tables are consistent

so this means every router's got the

same picture of the network and they all

agree on which networks are where

so here we've got router C advertising

the 1011 Network

when the net was converged all routers

will agree that that Network exists and

they will agree on how to reach that

Network so a will send it out of the

right hand interface B out to the right

hand interface and then C is directly

connected

now if this network goes down or the

interface goes down

relative c will remove that route to the

network from his writing table but

before this update is the center out to

be

router B sends a periodic update to

router C saying it knows how to reach

the 10110 Network

so this update makes for how to c think

that router B has an alternative path to

get there

obviously through some of the series of

routers it doesn't

uh have a picture of the entire network

and well it's got this directly

connected Network and it believes what

it has from other routers

so it will mark this uh route to get to

the 10110 Network as reachable through

router B

a periodic update from RTC will contain

that Network which we've already said

router B assumes it knows how to reach

that Network mentioned in the update

now when router B receives a packet

destined to the 10110 Network it will

forward it to router C

when Route 60 receives the packet it

sends it back to router B and this is

where the loop is happening

so unlike switching Loops the in writing

like the packet will last until the time

to live value which is TTL in the packet

header reaches zero

so you can see the time to live fields

in this particular packet here which is

a bgp packet capture

once the time to live value reaches zero

the routers then drop that packet

and disinfected protocols we've got a

couple of solutions

splitterizing and poison reverse so this

is split Horizon the rule is that if an

interface learns a particular route it

doesn't advertise that route back out of

the same interface now this causes

problems when you come to configure a

hub and spoke Network and there's ways

around it which we're not going to cover

here with ergrp and ospf in particular

you can change this rule or turn this

rule off and set of ways to get around

it so routing works

so router a learns about rata C from

router B what it won't do then is

advertise the network back out of the

same interface to router B because this

would breach the split Horizon Rule and

basically route and the networks

attached to router C can be reached via

B so it doesn't need to be re-advertised

back to router B and cause confusion

poison reverses a form of split Horizon

it uses a method to use um known as

route posing angle poison reverse it

allows the router to set a distance to

the network as Infinity this is for the

um

how many hops for example in rip

this allows the network to converge so

perhaps you've had some instability

the network attached to router E network

5 has gone down so router e will quickly

advertise that with an infinite distance

which is known as rat poisoning

so I've looked at Loops distance Vector

routing protocols bit Horizon poison

reverse that's all for now thanks for

watching

[Music]

foreign

networks vlans and sohos

so we finished talking about switching

and routing how networks communicate

with one another and so now we want to

talk about two other terms that we see a

lot when we talk about local area

networks and they're important to know

for the network plus exam

the first is called VLAN or virtual

local area network it has to do with

segmenting a physical local area network

into two or more virtual or logical

local area networks and we're also going

to discuss what they do and how we

Define memberships in vlans since this

is not a physical distinction but a

logical one we're also going to discuss

a Soho Network also called a small

office home office Network we've

probably seen this term in the past

because we deal with it when we talk

about Soho routers which are those

routers like the d-links and the Linksys

that you have at your home that allow

you to get for instance wireless access

although

these provide many different things

they're distinct from a regular router a

Soho router because a regular router

just does routing whereas a Soho router

does several different things now that's

an example of why a small office home

office is so such an important term when

it comes to network Plus

so virtual local area networks or vlans

are a type of local area network

configuration they're actually somewhat

of a misnomer though the word virtual is

really the focus of the name they're

really more segmented than virtual VLAN

can be described or defined as a group

of computers that are connected to one

another although they function as though

they are on different networks even

though they sometimes aren't so the

computers that are segmented together

are usually ones that are in a same

Department as the others for example we

might have an office building with four

floors

and the encounting employees could be on

every floor

a VLAN would allow them to all be

connected to one another

even though they're really

sort of sharing the network

with every other department in other

words

if we had the accountants and then let's

say the managers they would all be

connected to the same physical Network

in the building but we could segment

them into separate virtual local area

networks so that way they can

communicate with one another and other

folks can't communicate with them

they would therefore think that they

were connected physically to one another

or all plugged into the same switch even

though were you really using four

different switches one for each floor

now there's some very clear benefits to

having VLAN set up

first the security is increased this is

because when we segment a network

there are virtual boundaries and that

makes attacking the entire network very

unlikely it also makes sure that

accounting people are going to have a

harder time getting into the management

people's information

so again even though they're physically

connected all the same we're giving them

a virtual segmentation so that they are

separate and therefore it's a slightly

more secure

they also increase the performance by

freeing up bandwidth and reducing and

splitting up traffic from the network if

accounting for instance uses a lot of

bandwidth and management doesn't well we

don't want management to suffer because

accounting is using QuickBooks and the

servers so much therefore by segmenting

it we can make sure all of the traffic

that accounting is using is staying on

their segment and management performance

doesn't suffer as a result

we can also group users that often

communicate and share data and so this

network becomes far more organized this

is not just from security and

performance perspectives organization is

just from a logistical perspective as

well I can put someone in a VLAN and

automatically they're going to have all

the benefits that come with being in

that segmented area independent of their

physical location

finally it also makes the

administrator's job a lot more easier

because when everything is segmented up

things become easier to deal with I

don't have to create a specific set of

policies or security for one individual

when I can simply

uh put them into a VLAN and let it all

sort of work itself out

so here's an example of what a VLAN

might look like as you can see there are

four floors to the building with

computers on each of them and the

computers are all connected to the same

network I very much simplified this in

fact we would probably have uh switch on

every floor

remember this would be called the idfs

and then they would all come together

like we see here in one Central MDF but

for all intensive purposes they're all

connected to the same physical Network

however we only want the accounting

employees to share data with themselves

not with the graphic designers or the

marketing folks and we want them to have

their own segmented Network as well

so with VLAN we can actually segment out

the

counting folks into their own virtual

Network even though they're on the same

physical Network

the same could go for the graphic design

folks and the marketing folks they're

all split into segments with similar

employees and we would actually give

these vlans numbers for instance VLAN 1

2

and three

now there are three different ways that

VLAN membership can be assigned a

membership is a way that the device is

assigned to that specific VLAN for

instance the one two or three that we

just mentioned the first method involves

protocol-based vlans in this way

computers are assigned to vlans using

networking protocols that are in place

such as the IP address the IP number is

only used to determine the membership

but has nothing to do with the routing

of the VLAN Network so for instance we

could say all IP addresses from 1 to 100

are on a specific VLAN and all the ones

from 101 to 200 are in another

another thing we can do is what's called

Port based vlans

this requires that ports on the network

switch are assigned to specific vlans so

as you saw previously we had uh

accounting and marketing and Graphics

all in sort of different

um physical locations but they were all

plugged up to a central switch

so what we would say is for instance

any computers plugged up to supports one

through three are in VLAN one and the

ports plugged up to four and five or in

two and six and seven are three now

remember a lot of switches can have

perhaps 200 ports so this can get a

little complex

finally there's mac address based vlans

in this way you've heard of the physical

address and when you know that we can

use this to actually filter out

um using a what's called an ACL or

Access Control lists certain Mac

addresses from a wireless access point

well it works the same way with a VLAN

depending on the Mac address of the

computer that is being connected it will

automatically place it into a specific

VLAN of course the benefit with this is

because the MAC address is the physical

address of the computer and is always

hardwired onto that computer

I can move the computer into any

different port and it can get any

different IP address and it'll always

remain in the same virtual local area

network

now the other term we want to talk about

is a Soho Network or a small office home

office Network this is generally

speaking as the name implies a smaller

home office Network that serves between

one to ten users on the network now you

can have more users or less users

although I guess you wouldn't have less

users than one but generally speaking

it's really going to designate a very

small Network although they're smaller

in physical size and generally smaller

than the number of users they're going

to accommodate the network in the same

sort of way meaning we're going to use

some of the same protocols and devices

they're just going to be built

differently because they don't need to

be as powerful

so for instance here is a small office

home office Network you have two PCS in

it perhaps I have one in the living room

or one in the bedroom and one in my home

office and maybe even we have a laptop

as well

so maybe we have three different

computers ones for the kids one's for my

wife and one's for me

now

we have what's called a small office

home office router

now it's called just a router to many of

us but really this is a small office

home office router because it does

several things it has a built-in DHCP

server

for a lot of us it also is Wireless

so it's a wireless access point or WAP

it's also has uh plugs on the back so in

some ways it acts as a switch for us

although that's built into a router so

I'm not going to write that separately

it does something called Network address

translation which allows the IP address

coming from our internet service

provider on our modem which might be

let's say

126.43.17.3 to be shared among three

different uh internal devices

so that way when information comes in

from the internet it knows which device

to send it out to

and also does a couple other things for

instance it might have a firewall

and to do some other stuff we've

mentioned as well

no matter and it might even allow for

vlans actually

but no matter you can see that this one

device is taking on several devices that

we've talked about previously

this was your only uh experience with a

router and you might think all routers

operate this way in fact they don't we

just call it a router because that's

probably the most important function it

does which allows us to get out to the

network

but there's not floors and floors and

floors of stuff going on here and this

router wouldn't do very well

is because it's not built to if I tried

plugging a hundred computers up to it so

the real important thing here is as you

go forward in your career you'll

probably be seeing more and more of this

and if you're going to be supporting

homes or really small businesses then

you want to know that perhaps they don't

need a separate switch and router they

just need one device that being said if

a company is growing really fast perhaps

they need to purchase a separate switch

that then plugs into the router the

switch therefore can help work with

traffic internally of the network and

the router will help get the information

out onto the network

but it's important again to realize that

even though this is a small office home

office or Soho that's not the area or

the geographic location remember that's

just the name of this type of network

that it's going to have all the same

principles apply it's just the devices

might be smaller and less able to handle

a lot of people

so we've talked about uh virtual local

area network which is basically

segmenting

a lan or local area network into several

logical partitions

but physically everything is exactly the

same

we talked about how we do the

memberships for these we can do it based

on the port it's plugged into

we can also do it based on the Mac

address

or based on the protocol

which in some ways would be linked to

the IP address

finally we talked about a Soho Network

or small office home office Network

which the real reason we want to know

that is because the devices are going to

be less powerful

okay

and they're going to sort of converge

meaning that we're going to have a

wireless access point that's also a

router that's also a DHCP server whereas

in a large Network we would separate all

of this out

so that's sort of

finishes our discussion on local area

networks and lands the next lesson is

going to talk about wide area networks

or wans which we've already talked about

slightly when dealing with routing but

we're going to talk about that in a bit

more depth

vlans and drugs

we'll be doing some Labs on this as we

go through the course so don't worry

um if it doesn't sink in straight away

a VLAN is a virtual local area network

so it's not something you can see by

physically looking at the network you'd

have to look at the configuration of the

switches

it defines a broadcast domain in the

layer 2 Network

so just the same as

local area network using the switch

the switch will forward broadcasts

however if you have two vlans on a

switch for example the one on the top

right diagram there

the broadcast will stop as far as the

VLAN reason is you need a layer 3 device

which is normally a router in order to

send information from one network to

another so virtual local area network

for all intents and purposes it follows

the same rule as a normal Network or

subnet

so you can separate broadcast domains

even though it's on the same physical

switch by configuring a layer 2.

a VLAN is a logical division of switch

ports so if you had 20

switch ports physically on the switch

you could in theory have 20 different

um

devices each in its own VLAN

you need a router to pass packets

between vlans some switches actually

come with a

a writing module that you can insert

which is a bit beyond CCNA level to be

honest just for your own information so

vlans can spun multiple physical

switches

so we've got switch one two and three

here and you can see we've got a couple

of different vlans configured

best to have all hosts in the same VLAN

on the same subnet that's all really

wanted to say on that particular subject

but it's just the best

um idea

no need for a variety to communicate if

all the devices are all on the same VLAN

some of the benefits or why would you

bother logical separation just gives you

better security

helps with the broadcast issues if you

do up on better utilization of your

bandwidth

Avila marking obviously it has to be

some way if you're chopping your network

into vlans for the VLAN to identify

itself

vendors use different approaches for

example Cisco created ISL into switch

link which is a proprietary for Cisco

devices they've actually moved away from

ISL now though many of their switches

still support it and they moved on to

IEEE standard 802.1q

called frame tagging frame tagging

inserts a 32-bit tag field into the

original frame

so concept of a native VLAN is something

you should be familiar with as a Cisco

engineer

a native VLAN on Cisco devices certainly

is all allocated to VLAN one by default

all devices in a VLAN will be assigned

to VLAN 1 unless you configure and then

to be in a different VLAN

so traffic on a VLAN on that on the

native VLAN is not tagged it's not given

the 802.1 Q tagging

well the reason is it uh we have it is

it allows the switch to communicate with

the device that doesn't understand

802.1q

it is a security risk which we'll cover

later on

vlr membership so you can assign VLAN

devices or ports to a VLAN statically as

a network administrator

it can be dynamic based upon device Mac

address

switch ports are assigned to vlans and

then devices plug into the physical

ports

access ports connect to network hosts

a network hosts connect to access ports

it works both way around that sentence

if you want to connect to another switch

and you're using multiple vlans then

these connections are known as trunk

ports

so trunk ports uh will connect more than

one VLAN which is connecting more than

one VLAN together

so a special Port type carries data from

multiple vlans it can use ISL although

that's pretty much been depreciated now

so you shouldn't be looking at it for

the CISCO exams at least

frame tag in is transparent to end hosts

so the tag is attached by the switch

sent to another switch and before it

reaches the end hosts the tag is

actually removed

trunkport modes we can manually set the

interface to trunk with the command

switch Port mode trunk

trunk modes include on which is manually

set the interface to trunk off you can

tell it to never become a trunk

Auto silently wait for a request to

become a trunk desirable which means

actively seek to become a trunk or no

negotiate you'll cover these commands

in detail when you come to do the CCNA I

probably won't be doing

um

covering these commands and how to

configure them for the primer

configuring a VLAN you need to manually

add the ports to vlans

and you need to set your ports to trunk

so here's a configuration I've just done

one side because the configuration is

the same for both switches

I've created VLAN 5 in config mode by

typing VLAN 5.

I've given it a name called RND so you

can name your vlans it probably makes it

easy for you to manage interface fast

ethernet zero slash one I've created

switch Port access VLAN 5. so this is

telling the port that it's a switch Port

layer 2 and it and the device is belongs

to VLAN file that's connected to it

I've gone on to my fast ethernet 0-15

switchboard trunk encapsulation.1q

to tell it what encapsulation to use

that won't work on a 2960 switch because

2960 will only recognize.monkey

and I've told it to become a trump port

okay so you'll be labbing some of this

up later on but for now that's the end

thanks for listening

[Music]

wide area networks implementation and

administration

in the previous lesson we discussed

local area networks or lands these were

networks that were restricted to a

specific single geographic location now

in this lesson we're going to talk more

about wide area networks or wans we're

going to Define them and talk about how

they compare to local area Networks

so we're first going to define a Wan

which we've talked about in general

before and then we're going to identify

some of the steps we would take to

implement one uh specifically some of

the things that make it different from a

local area network or LAN

finally we want to identify some of the

administrative tasks that go along with

or that challenge us as Wan

administrators specifically backup and

security

so a Wan is a wide area network and

though it functions very similarly to a

lan it is different in that it's the way

it's set up and the way it's connected

when is uh Network that's not restricted

to a single geographic location like a

lan in fact it's often made up of

multiple lands all linked into one big

win and these lands can be across town

from each other or even across the globe

now we've talked about some other terms

for instance can like a campus area

network or city area network and a man

or a metropolitan area network but all

of these could be in some way shape or

form are considered a Wan and of course

the biggest win that's out there is the

internet

usually referred to as the cloud because

on network diagrams a cloud is used to

represent it

now because of this Geographic distance

lands are generally slower than lands

because they have to as it makes sense

travel a longer distance to deliver data

just like if I sent a letter

internationally it's going to take

longer to get there than one across town

or even across the country that being

said newer Technologies such as fiber

optics and etc etc are making Wan

connections faster and therefore are

connecting parts of the globe that have

never really been connected before

so here's an example of what a wide area

network might look like let's say for

example that a company had two branches

one in New York

and the one in Houston each of the

branches has their own local area

network

here the one in New York and the one in

Houston obviously these are simplified

so imagine that instead of just two PCS

on each there are maybe five thousand

and instead of just one server maybe

there are 20. but they each have their

own switch to talk locally to one

another through Mac addresses

then there's a router on the edge of

each Network that connects it out to the

WAN or the internet

of course the WAN if configured

correctly can also connect these two

lands as though they seem like they're

in the same location just like their

next door now we could set up our own

Wan in other words we could have our own

cables and wires running through uh from

New York to Houston and that's going to

get really expensive and so we've come

up with Technologies to use the existing

Wan that's out there I.E the internet

in order to create secure connections

between two locations without having to

actually physically lay our own chords

however the idea is the same we connect

two lands through a Wan

and this allows users in both locations

to share data easily

a great example of how this is deployed

worldwide would be Banks or for instance

American Express or chase

you can buy something with your American

Express card just about anywhere in the

world and it still takes the money out

of your bank or puts it onto your

account almost instantaneously

now the process of establishing a wide

area network is really it can be quite

complicated although it's gotten more

and more simplified over the years so

I'm just going to go over some of the

basic steps and do it in a really

simplified manner uh basically what you

need to understand for Network plus a

good way to start with the Implement

implementation process to set up what we

call a VPN or a virtual

private

Network so the name implies it's not

actually a private Network that would be

one in which I actually have a cord

stretched across the country connecting

one computer to another rather this is a

virtual private Network

so this is a type of Wan and what it

does is it actually allows us

to use the public Wan the internet and

create a tunnel through it

called a virtual private Network that

then makes it seem like the two

locations are right there next to each

other the benefit of a VPN is that it

makes it secure

so once you basically install the

settings you need to put in some

administrative policies and rules so not

just anyone can tap into your tunnel

otherwise it wouldn't be very secure and

there wouldn't be any point we also need

to select certain users who are going to

be able to get access to it and how we

want to allow them to have these remote

capabilities we'll talk about a VPN in a

bit more detail and we've talked about

it a bit in the past

finally we have to add the user accounts

to our local networks

so that then they can communicate

throughout uh the Wan

this can be configured using either IP

addresses or Mac addresses or domain

names so just to go back over that again

I create the VPN I give access to the

users and then I connect those users to

the network perhaps I connect them to

the network from home perhaps from their

own internet access at home or their own

internet router but in some way I have

to give them access and that generally

involves some sort of special software

or device and some sort of

authentication such as a password or pin

number

now being the administrator for Awan can

actually be pretty demanding because

it's not restricted to a single location

the job involves a lot more than being a

land administrator because you might

have a land that's all in New York but

if I have a win I could have offices all

over the world so the main tasks though

are still the same they're just

generally on a much larger scale in fact

almost every task that both

administrators would share is just

larger in scale and just a little more

difficult for the wan to admin

so backups are just as important on a

Wan as they are in a land if not more so

because data loss of any kind is

something that needs to be avoided it's

the way an admin's job to be in charge

of backups for the entire wide area

network and make sure that everything

goes well the actual process of backing

up everything is virtually identical on

both networks however with Wan it's much

more difficult because as we said before

lands span over two or more physical

locations geographically and are

grouping Lan networks together so we

need to not only back up stuff at the

individual Land locations but then we

need to put all that together into one

big huge backup of course one of the

main differences we mentioned at the

outset is speed and so when we're trying

to back stuff up to a wan to the

internet

speed becomes an issue I can back

something up really quickly if I plug it

into the computer when I start going

over the network that's a little slower

and then when I start going over a Wan

it's going to get a little bit slower

too so full backups can take days

depending on the size of the WAN and

obviously the issue with that is if it

takes days for me to back something up

and I'm working on it then by the time

it's backed up it's actually hasn't

gotten the backup at all and so we have

to deal with all sorts of stuff when

we're doing this

so as you can see here I generally might

have some sort of off-site

backup area that all the data would sort

of Route into sometimes what we'll do is

we'll actually back stuff onto a local

backup

and then the local backup will be backed

up to a cloud backup or a Wan backup

so we have to deal with space issues and

we also have to deal with speed issues

now when it comes to backups as you can

imagine that's some pretty important

data that's flying over the network and

so I also need to make sure not only my

backups but my entire network are secure

and this is a massive job for the

administrator of Rowan in fact generally

when administrators don't do this they

hire someone else to specifically focus

on security again the big difference

with Wan is that the network is not

limited to a single location so there

are many more points for Access for

people who might have nefarious uh

purposes to get into our Network

this means the administrators not only

controlling the security at each

physical location but also the security

of the entire network as a whole

theoretically if an attacker were to

infiltrate one of the lands it could

infect the rest of the WAN so we have to

have a lot of fault sort of safety

measures in there as well it makes our

job really difficult and we not only

have to spread against these attacks but

also the spread of attacks if one site

gets infiltrated well I can't do

anything about that at that point but I

want to make sure all my other sites

don't get infiltrated as well

so here we see the same wind from

earlier but unfortunately a virus has

been sent by a hacker and it's making

its way through the wan to the other

land this is an example of something an

admin would have to be diligent about in

some ways what we want to do is create

some sort of wall here so that way the

virus or the logic bomb in this case

couldn't make its way over and just got

stuck and stayed in Houston while it's

still a pretty bad scenario at least New

York hasn't gotten infected

so in this module I really briefly

talked about a Wan or a wide area

network

remember a Wan is comprised of several

lands that are connected

over a geographic area

in some cases we're going to connect

them through the use of what's called a

VPN

well we have a VPN or a virtual private

Network it creates a tunnel over the

Internet which is our public switched

Network or our public network and we

create a private Network within that

using all sorts of protocols we'll

discuss so that way these two lands can

communicate as though they are actually

one Lan or they're right next to each

other we also need to have user accounts

so that way the users

can't just not anyone can get onto a

network they have to have a specific

password authentication Etc and those

users also have to have access somehow

whether that's through the internet or

they actually are physically connected

through our land site

we also talked about some of the

administrative tasks that can be

difficult for lands specifically backup

where we're dealing not only with speed

but also with amount of data

and we talked about security we're not

just stopping intrusions

but we also need to limit the spread of

an attack

[Music]

wide area networks Wan transmission

technologies

so in the last module we talked very uh

briefly and in an overview sense about

the implementation and administration of

wide area networks now the reason we

didn't get into too much detail is

because it gets quite complicated when

we talk not only about connecting

computers together in a local area

network but in a wide area network and

as a result the Technologies become more

and more complex and just like we have

people who specialize in lands they're

people who specialize in lands since the

purpose of network plus is to give you

an overview of all the stuff we just

want to get you familiar with certain

terms so in case you were to come across

them you would sort of know where to

look or what to start with when you look

for more information now in this module

we're going to talk a little more

specifically about Wan transmission

techniques again we're going to look at

this from a mile high view so the

techniques then the transmission

technologies we're going to talk about

are specifically ISDN which you might

remember if you've been around for a

while it's mostly been supplanted by DSL

and cable to this uh nowadays as

actually you have most of these

Technologies but some of these are still

around and you probably have heard of

them so ISDN is the first we're going to

talk about we're also going to talk

about t carrier and if you've ever seen

the term a T1 or T3 line that's what

this is referring to we're going to talk

about Sonet which is responsible for a

different type of classification it's

also using some Optics which is why it's

a bit faster and required a completely

different form of rating the cabling and

the speeds and then we're going to look

at some technologies that allow the data

to transmit over this stuff these T

carrier and sonets including x25 and

frame relay x25 was supplanted by frame

relay and ATM which is not the thing you

put your card into to get money out of

but rather a technology of protocol that

allows us to communicate over when

Networks

so the first one we're going to talk

about here is the integrated Services

digital Network or

ISDN now uh the ISDN is very high speed

but it's also high cost and the reason

for that is because in order to use ISDN

a special phone line is required to set

it up now the line is paid for monthly

just like with any phone line and this

is where the high costs come in because

the service is pretty expensive to pay

for every month in order to set up a

connection the phone line has to dial

the address of the receiving computer

very similar to the process of calling a

phone on the other end and once the

connection is established you can drop

it by just hanging it up so if we were

to consider this for instance to be our

um uh ISDN line you would notice there

is sort of a box here and that's because

we need a special box to allow the istn

to communicate and it would then

communicate onto the other side to the

ISP now what's interesting here is this

is actually a plain old telephone system

line or uh by the way Plano telephone

system or pstn public switch telephone

Network so this is using uh old

telephone technology but the difference

is instead of using the one that's

already been installed into your home or

to your office it's actually another one

that has to be laid down which is how

it's different from DSL now there are

actually two different types of ISDN

we've talked about these in a plus as

well one is the Bri and the other is PRI

Bri by the way stands for basic

rate interface and this one stands for

primary rate interface primary is a bit

faster

but it's also a little bit more

expensive now there are certain speeds

these operate at generally 64 kilobits

per second or 128 kilobits per second

again that's pretty slow when we compare

it to modern day DSL or modern day cable

Technologies but this was a dedicated

line specifically from you to uh the ISP

which is the reason why even though it

was a little less fast it was still used

although nowadays we don't see it used

as much because it requires special

technology special boxes special

equipment and so on and so forth

now the next technology I want to talk

about are called t carrier lines T

carrier lines are dedicated digital

lines that are leased from the telephone

companies much like ISDN but they're

high speed and they establish a stable

connection on both sides just like ISDN

now these connections are always open

unlike isdns so communication can be

made between the two ends whenever it's

needed there's no hanging up in other

words because they provide such a good

dedicated link they're also expensive to

use on lands although they were faster

and so we saw a lot of companies used to

have T1 or T3 connections and they might

still do now there are different types

of T connections available depending on

the speed you require the first T1 is

the slowest of the four types now

like the other three it does create

dedicated ends and it's secure

and t1s are generally going to be used

to connect lands together so for

instance if I have my Lan on in one side

of the city and you have another one we

might get or lease a line from the

telephone company to directly connect

them if we don't want to use the

internet nowadays we have the internet

so a lot of organizations are going to

use that and just get a very fast

connection perhaps a T1 or T3 line

between them and their ISP your internet

service provider you might sometimes see

this by the way referred to as Digital

Signal one or DS1

so if you ever see DS it's the same

thing as a t line now T2 as you can

imagine are slightly faster than T1

lines they're not much different they're

for some reason used a little less it's

probably because the speed is not worth

the uh upgrade uh and because

the T3 is actually even faster than T1

and 2 T2 put together so if we add both

of those together we'll get a T3 this is

sometimes also called a DS3 and t1s

and t3s

are the most commonly one used T lines

that you'll probably see out in the

field

T4 is even faster in fact it is a

combination of all of the top ones

meaning it's faster than all of them

combined but it's also pretty expensive

and for most part we're going to see if

you really want to fast line a T3 and if

not you'll probably see a T1 out in the

field a lot of companies maybe 10 15

years ago used to connect via a T1 or a

T3

sometimes you'll still see that if it's

a very large company otherwise they're

going to connect via perhaps a DSL or

cable connection generally commercially

again this was before you had cable and

DSL at everyone's homes so now the

technology has shifted a bit but it's

important to know about this for Network

plus because they're testing knowledge

that you might see even Legacy

information meaning old information that

you might run into or encounter at an

office or a building

now in 1984 if you recall your history

or if you were around then you might

recall that 18t in the United States

held a monopoly on the network carrier

industry I.E phones so preceding this

smaller companies were given a chance

and a challenge to come up with a system

that was going to rival a t that the one

that they had so a company called Bell

Communications which you might have

heard of came up with this called the

synchronous Optical Network or Sonet now

sonnet is fiber optic okay so rather

than being copper we're dealing with

fiber optics which uses plastic or glass

and delivers information and either

voice data and Video in much higher

speeds as a result because it's using

light pulses

now this achievement was so great that

it sparked a new system of defining data

rates meaning that the old systems uh

just didn't

it was so slow in comparison there was

nothing that could sort of uh uh counter

this and so we start seeing the OC

levels like for instance one you might

have seen is

oc9 and that would be really really fast

now don't worry about knowing the

specific speeds for the network plus

exam that's why I'm not covering them

what you just want to make sure of is if

you see OC versus like a T1 or T3 you

want to know that the OC is generally

going to be faster because again look at

this word Optical carrier levels

now in the mid

um 1970s we had something called x25

which was everywhere and this was

technology that was developed as a way

to send data over copper wiring so not

that OC stuff but more the t1s ETC and

isdns but during its creation everyone

in the networking Communications world

had a part in creating and implementing

it you might see x25 or terms and you

used to talk about how they would take

data and send it over these uh this

technologies that it had and its format

was virtually Universal however it was

really limited by speeds because of the

copper wiring and just because of the

way that the protocol worked uh which

I'll write up here

and so it was replaced by something

called frame relay now frame relay is a

protocol that was developed basically to

transfer between LAN

and Wan end points in other words

between My Lan and the ISP or my larger

wide area network the way it functions

is not important just know that it

functions similarly to x25 but it's

faster

and it has a more modern build behind it

they're also both called packet

switching Technologies and we'll talk

about that later but frame relay can can

send smaller packets and it can send

them faster

we'll talk more about uh packet

switching in the next module

finally I want to talk about

asynchronous transfer mode or ATMs if

you ever see ATM on the test this is

what they're referring to a wide area

network uh transmission or transfer mode

it was introduced in the 90s as a

successor two frame relay and it was

really considered a breakthrough because

it was what they call an end-to-end

solution that could work either desk

from the desktop or remotely what this

meant is that it could work on a Wan a

wide area network and within the land

however this sort of proves not really

to be true because the technology sort

of got

for lack of a better word pushed out of

the land market because other

technologists came around that were just

better it was actually pretty expensive

to use but it did have some benefits one

of the main ones just like with the T

aligns is it could transfer data voice

and video it's also a packet switching

technology something we're going to talk

about and it's pretty fast and one of

the major things we're going to talk

about with it is that it used what are

called cells and the cells were 53 bytes

long which is fairly large for a packet

of data and I shouldn't say even pack it

because what it really we're talking

about is it was replaced by cells so

these cells have proven to work more

efficiently for transferring than

packets that were used by frame relay

and this is really sort of the legacy of

ATM was using these cells that had a lot

more information in them than the frame

relay packets which were much smaller

obviously the more information we could

cram into a packet the faster we could

send it the quicker we can get

information to the other side

of a network or a wide area network

and if we just look at this this is just

to show us that it has again voice

data and video

all in one

cell which was sort of the amazing thing

that this technology ATM did good way to

remember it is to think about going to

the ATM you can check your balance you

can get money you can pull out of your

savings you can pull out of your

checking and so it sort of does a lot of

things when it comes to your bank same

with the ATM cell

all right so those are all the WAN

transmission technologies I just want to

briefly go over obviously we took a very

cursory overview of them and and you

could probably Google and find a lot

more information that's going to go over

your head and you don't need to know

that for Network plus but what I want

you to remember again is that ISDN was

used it really either came in that BPI

or rather Bri or PRI modes PR was

slightly faster it was either in 64

kilobits per second or 128 kilobits per

second it worked over the existing pots

or pstn phone system but it was still

relatively slow we don't see it much

anymore although it was pretty big maybe

15 years ago the T carriers the big ones

you're going to see are T1 and T3

remember that T3 is faster than T1 Sonet

as well was introduced

excuse me it replaced

the sort of tea way of looking at speeds

with the OC

system OC

is fiber optic and if you think about

the O in there being optic that's why it

was faster x25 and frame relay both ways

of transferring

when data this was replaced mostly by

ATM both of these are what we call

packet switching which we will look at

in the next module

and the important thing with ATM again

not the thing that you put your money

into but rather a Wan technology it was

marketed as being

end to end meaning it could work from

the computer to the computer although

nowadays we really use it in Wan

Technologies from a land to a land

endpoint and the other thing it really

introduced was that 53 byte long info

cell

which again can hold video voice and

data in it

[Music]

thank you

look at the module 9 lesson 2A least

lines

I'm gonna look at T1 E1 T3 E3 and sonnet

synchronized Optical networking

these are a syllabus talking points so

kind of need to cover some of the things

I think could come up it's uh Ali you've

got a lot of choices when you want to

connect your small office or even a

larger office

across to the internet or to another

remote office somewhere else that you

own

now one of these options is a lease line

which is a dedicated telecoms line

now you don't install the line it'll be

the roads will be dug up or wherever

they put their cables will be

um all laid by telecoms company and

you'll release that line for a fixed fee

usually monthly and you have to sign a

contract this lease line is available to

you all of the time 24 7.

so since this dedicated line it's not

shared with other users here's an

illustration it's an image from

Wikipedia at the bottom you've got

remote users using the public uh switch

telephone Network they're dialing in

I suppose nowadays they'd be using

broadband and um vpns they could be

working from anywhere

but you've got two Regional Offices on

the left that need a dedicated

connection of 24 7. they'll go through

the telecoms network using a lease line

foreign

based on the technology the bandwidth of

a lease line varies typically between

56k and 2 Meg to be honest there's

unlikely be using 56k unless you just

wanted to have

um like some sort of keyless entry

system perhaps for a gym where it just

needs to authenticate people but even

then the costs are so low now that um

it's unlikely to be that slow

okay some advantages we've already said

it's it's your connection dedicated to

you and you can choose how you allocate

that bandwidth if you want to use it

mainly for video conferencing or some of

the some of the use disadvantage they

are quite expensive

and typically used to connect businesses

that have a geographically distant

offices so they tend to be um Somewhere

Out In The Sticks

and a bit more difficult to use other

connections for example a broadband

connection with a VPN

always active and like a dial-up

connection dial-ups are fairly old

technology now

and quite expensive

okay the telecoms company will charge

you monthly for use of the lease line

fee varies based upon the distant speed

of the connection also where you are in

the world

um some places the Technologies still

emerging

some places still established

so level level of quality is assured

it's not as if you can use more

bandwidth at certain times of the day

like frame relay and lesser others

uh quite uh old technology still in

quite prominent use but the technology

is quite old originally used to connect

your mainframes to remote sites

so a few examples that they mentioned in

the syllabus the T carrier and e-carrier

T carrier one e carrier one and then T3

and E3

the T1 transmission system originally

developed by a t

1 induced introduced back in 1961.

originally uh developed to to transmit

24 phone signals at the same time over

uh the copper wire

he uses something called TDM time

divisional multiplexing this mixes up

the signal in order to use

um multiple signals over the same

physical link

I don't think they go into any detail on

TDM in the exam there

so T1 will give you a bandwidth of 1.544

Meg upstream and downstream so

synchronous T1 system is used in America

Japan and South Korea e the e-system is

generally used in Europe

the bandwidth level of T1 was originally

called the digital signal level 1 or DS1

I mentioned before the T1 line has 24

channels each channel is called a ds0

and you could have one two three of

these channels or all of the channels

depending on how much you want to pay

and how much bandwidth you need

each channel is capable of transmitting

data at up to 64k

uh lease line T1 multiple channels

provide flexibility so I've said you

could already choose some channels or

all the channels E1 is the European

version of T1 however because of the

infrastructure that was in place at the

time you could get up to two Meg

2.048 mag

this has 32 channels in each Channel's

capable of transmitting data up to 64k

you can add them all up and then there's

a um a signaling Channel also

T3 is equivalent to bundling together 28

T1 line so much faster

also referred to as DS3

since there are 24 channels the T3 is

capable of carrying 672 T1 circuits so

multiple companies will be using these

it's not likely that B1 companies

so you get up to

44.736 megabits per second with the T3

lease line if you add the whole line

30 times faster than T1

E1 is the equivalent to 16 or E3 sorry

equivalent to 16 E1 lines

512 E1 channels so you get up to 34.4

mag there

so T3 has more bandwidth than E3

sonnet I think is mentioned in the

syllabus which is why we've got it here

synchronous Optical networking this can

be used as lease lines also but it uses

fiber cabling instead of copper

you get um higher bandwidth for that

obviously because it's using fiber optic

um the transmission of solid fiber

networks is specified as Optical carrier

or OC transmission rates

oc1 is a transmission line with speeds

of up to 51.84 Meg

oc3 you get up to 155.52

and then OC 12 you get up to 622

megabits per second

uh the oc-12 is typically used by your

isps as a wide area connection you

wouldn't be using it in a

and small company for sure

so we've looked at T1 E1 T1 T3 and E3

and also solid networking

thanks for watching

[Music]

foreign

module 9 lesson 2B wavelength division

multiplexing bit of a mouthful but it's

a new um

objective in the network plus exam

we'll look at what is a wdm

that he said wmd wdm system course

length division multiplexing cwdm again

we love our abbreviations here a dense

wavelength division multiplexing

so what is it basically the idea is to

get the most you can out of what you've

got and this

um instance what we've got is a single

optical fiber and what we need to do is

is get as many signals to cross this

fiber at the same time as possible if

you just had one signal pass in then

um so the internet would grow into a

whole basically it allows bi-directional

Communications over a single fiber so

two directions

uh wdm uses a multiplexer which is um

you'll often see it referred to in

diagrams as mux mux and then a d

multiplexer on the other side dmux

d-e-m-u-x

so this um if we just go back sorry it

um

the multiplexers that the transmitter to

combine multiple obstacle signals of

different wavelengths and at the other

side this needs to be demultiplexed back

to the original separate signals

wdm systems mostly used by telecoms

companies because of the capacity of the

network and the again the idea is and

getting more out of less so they can

expand the network without having to lay

more fiber optic cables which obviously

take uh takes a lot of time and money

wdm they're divided into two types and

these are based on the wavelength

patterns that are used CWD

um and DWD um

wavelength division multiplexing through

um dwdm and cwdm these they use multiple

wavelengths or lights but they differ in

the spacing I'll show a diagram actually

in a moment

um so in the following factors a

wavelength on the number of channels the

ability to amplify the multiplex signals

in the optical space

cwdm uses a smaller number of channels

you can use four or eight channels with

large space in between the channels the

bandwidth of each channel is

3.125 gigabits

so here's an example of cwdm used to

transporting data within 100 kilometers

So within a metropolis area

an example of cwdm is 10 base lx4

Network it can transmit data at up to 10

gigabits per second

cwdm cable televisions actually use this

where different wavelengths are used for

the downstream and Upstream signals

a dense wave then dense wave length

division multiplexing dwdm uses a large

number of channels it could be 40 80 or

160 but they have small spacing between

the channels and here we go is an

example from I'll put the link in down

here you can see the difference here

between the spacing and obviously the

numbers

um

the numbers are shown in the diagrams

there cwdm you can see the spacing where

it's DW DM

um very hard to see any spacing between

the channels

okay the high number of channels was the

reason for the name dense wave

typical dwdm system would use one of the

following 40 channels at 100 gigahertz

spacing 80 Channels with 50 gigahertz

space in

the bandwidth of a single channel is 100

Gig

used for transporting data over long

distances mainly used as the internet

background so this cable will be laid

over long stretches and um under the

ocean

into interconnects large strategic

computer networks and core routers

all right so we looked at what is wdm

the system and cwdm

dndm no dwdm sorry typo

all right that's all for now thanks for

watching

[Music]

welcome to module 9 lesson 2C uh

multi-protocol label switching mpls

so what is it a label switch path

benefits tunneling

[Music]

it's just an overview really because

they mention it once in brief in the

syllabus

but an mperls Network it provides one

connectivity between two geographically

distant offices so it's one of a number

of methods for connecting across a wide

area network and obviously each has its

pros and cons which we'll go into mpls

it's high performance it's packet

switching a packet forward in it uses

labels to address packets in the

telecoms network

now uh it's called label switching

because it makes forwarding decisions of

the packets based upon the values of the

labels and as opposed to the usual way

which is looking at the IP headers

so this avoids having to look at the

routing table lookups and all of the

problems associated associated with uh

routing table lookups

cool concept is labels are assigned or

pushed into Data packets this is the

packets are labeled the routers in the

impulse Network make forwarding

decisions based upon that label

you're still without having to examine

the actual packet it's only the label

has to be examined

so say remote office say what's the same

package to remote office B

and the data sent by a reaches the mpls

network the data will be labeled just

like how we'd label

um a packet if we were sending it by

shipping

and then the routers in the mpls network

will act like a courier service the

routers do not open the packet they just

look at the label and decide where to

send it for the next destination

process continues until you reach the

edge of the mpls network when the label

is removed or popped before being

forwarded to the remote office B

here's an example of a mpls network from

netcerts.net

the labels in the mpls network have the

information that tells the routers where

to forward the packets this is a

simplified diagram where the IP packet

has gone across to two routers and then

it's hitting the mpls network at router

p e a which adds a label and then the

label is finally removed at router p e

Zed

so there's only three routers involved

in the mpls network here

so as I said this is different to the

traditional routing where each packet's

header has to be examined each router

step by step has to do complex lookups

and obviously deal with all the other

issues associated with routing

a label switch pass the data

transmission in an mpls Network occurs

through a path called the label switch

paths

this is the sequence of labels that each

and every nose along the path that

establishes between the source and the

destination this is all actually set up

before the data is transmitted

multi-protocol basically means a number

of protocols can be used really the only

protocol left to send over mpls is IP

and ipx SPX and other such protocols or

apple talk aren't used anymore at all

npls is often referred to as layer 2.5

because it sits between layers 2 and

layer 3 of The OSI

some of the benefits not dependent on

layer two technologies such as ATMs

sonnet and ethernet

it can be used to carry different types

of traffic

and

ATMs on it and ethernet frames

tunneling mpls can control the entire

path of a packet by tunneling through

the intermediate routers that span

multiple segments

this is a unique feature of mpls it's

used in provisioning in mpls based vpns

which is actually outside the syllabus

all right so we've looked at mpls LSPs

some of the benefits and we've mentioned

tunneling we haven't gone into any

detail obviously that's all for now

thanks for watching

[Music]

welcome to module 9 lesson 2D an

overview of GSM CDMA and Y Max again

we're just hitting a few syllabus topics

that comment here kind of mentioned in

passing really but they are marked down

there

look at what is 2G

um you may have be familiar with it if

you've had a a mobile phone or I think

you call them cellular phones in um

America perhaps

enhanced rates for GSM

LTE long-term Evolution and CDMA

so what is it it stands for global

system for mobile Communications

I used to actually be able to plug an

adapter

into your

um a laptop

and use a GSM card for accessing the

internet but it was pretty slow my

experience was pretty unreliable and

pretty expensive so not fantastic but um

if you were desperate it kind of did the

job developed by European Telecom

standards Institute

Etsy

and this is the protocols for second

generation the 2G cellular networks

digital used by mobiles

the original standard was for 2G

Wireless telephone technology and it

became the global standard for mobile

Communications a bit left behind now

so GSM is a cellular network that uses

radio signals for mobile and mobile

comms

the cellular network is a mobile network

that is spread across the land area

called cells

one or more fixed transceivers or base

stations were probably more familiar

with they provide each cell with network

coverage obviously

the further away you are from these base

stations the poorier signal light is

until at some point you'll have no

signal at all

um we commonly call them mobile phones

during the cellular network calls

all right so what is 2G second

generation as we've said they use radio

signals developed as a replacement for

the old cellular network they used

um analog radio signals so that was a

real old school and stuff

they were quite easily hacked into at

the time you if you had the equipment

you could listen to people's

um telephone conversations with a

scanner

the original GSM standard was actually

designed for full duplex voice telephony

it was just adopted for data later on

originally operated at 96 bits per

second

which is pretty darn slow evolved over

time to allow Datacom through an

enhanced GSM technology called Edge or

enhanced data rates for GSM evolution

this was considered a pre-3g radio

technology

it's part of the itu's 3G definition and

the idea is it delivers higher rate bits

per radio channel so it's three times

faster than ordinary GSM also used for

internet connections

a long-term Evolution LTE is today's

mobile networks used something called um

LTE

commonly marketed as 4G you may have

heard 4G LTE

high-speed data rate access based on the

edge and HSPA network Technologies which

are Legacy

download speed is 300 Meg upload is 75

so it's asynchronous

CDMA is code division multiple access

this uses a special spread Spectrum

technology and basically the idea is

multiple users can communicate

independently but using the same

bandwidth and they shouldn't in theory

be any interference on the connection

uh represents a second generation 2G

Digital radio solution

uses the spectrally efficient technology

for mobile communication

all right moving on to Y Max

worldwide interrupt interoperability for

microwave access now what do they've

shortened that one technology is based

on 802.16 standard which you can look up

in your own time

it delivers a wireless Broadband

Services anytime and anywhere

here's an image from conique.com

of indirect access with the outdoor

customer premise equipment connecting

through a base station when you've got a

poor

um connectivity and but you've got the

signal goes through multiple paths

uh the 802.16 standard is developed for

providing an online science connectivity

so it'd be quite useful in um

areas where there's a lot of buildings

and things in the way trees and other

buildings and antennas

why Max is sometimes referred to as

Wi-Fi on steroids similar to Wi-Fi but

can provide Broadband access to a large

area supports Communications over a

maximum of 30 mile radius

there are other available for fixed

usage or mobile

so why Max is the standard which we've

already said download speed is up to 37

Meg and the upload speed is up to 17.

mobile y next is based on the

802.16a standard from 2005. and this the

got a throughput of up to 100 Meg

so we've covered in brief GSM 2G

enhanced data rates for GSM

LTE CDMA and Y Max that's all for now

thanks for listening

[Music]

wide area networks Wan connectivity and

voice over IP

in the last module we discussed the

different types of Wan switching and the

different transmission technologies some

of which are going to reappear in this

module that's because uh transmission

technologies and connectivity options

are going to go hand in hand so we're

going to talk about some of the WAN

connectivity options that we have

including a least line

packet switching which is different from

circuit switching we've seen in the past

something called cell relay which is the

name implies it's related to ATM

and then we're going to discuss briefly

voice over IP which is something that

will come up again but which is more and

more become a necessary part of our

networks that is making phone calls over

our internet Network or our ethernet

Network rather than over the plain old

telephone system or public switch

telephone Network and just to recall

that's either called pots or pstn that

was the phone network we used for lots

and lots of years until we started

getting more into a why internet wide

world

so

when we talk about voice over IP I want

to bring up a very important protocol

called sip if you see sip on the test it

is going to be directly related to voice

over IP

now one of the ways in which wide area

networks can gain connectivity is

through a leased line we've seen this in

the past module at least line is sold to

a company for a set amount of time thus

the word least

now a least line provides steady

permanently set up connection such as a

T1 connection or perhaps even a T3

connection or oc9 connection this

connection usually allows data voice and

internet connectivity to pass through it

now typically these are used for

establishing a Wan and connecting two

different geographical locations to One

Network though this connection is

permanently there it can only be

accessed as long as the customer is

paying the lease for it this is where

the disadvantage to it is this can be

pretty expensive to buy a lease for

because again if I have an office in

let's say Manhattan and I have an office

in Houston the idea is I'm leasing a

direct line

between the two and as you can imagine

because I have my own line that's going

between these it's pretty expensive the

reason I lease it again is because I'm

not a telecommunications company I can't

just lay this cord I need them to lay it

for me and then I'm going to lease it

from them

so the upside to this although that's

the downside is that it's the most

secure connection that we have

now in the last module we talked about a

t carrier lines and a T1 line can be

leased and provides a secure connection

so therefore it is a leased line

and we also talked about in previous

lessons switching we talked about how

important switches were to the

functionality of a local area network

they provide a communication path

between two endpoints and they manage

that flow of data so that way we don't

have a bunch of traffic going on in

effect they basically make sure that

packet going from one location gets to

the other and doesn't sort of interrupt

the flow of all the other packets that

are going on now in Lan these two

endpoints aren't very far away from each

other however on a Wan or a wide area

network these endpoints could be on

opposite sides

the globe and that's why switching is

such an important topic to understand

now when it comes to a win or a wide

area network there are two different

types of switching there's packet

switching and there's circuit switching

packet switching is when the data is

broken up into smaller chunks

or

pockets

and then they're assigned a source and a

destination and they stop at different

nodes along the way

every packet has these assigned to it

because they don't always stay in the

same path as the other packet and I'll

show you a visual to clarify this in

just a second they're usually going to

split up which paths they're going to

take in order to avoid colliding with

each other and to make it much faster

this principle of packet switching is

sort of similar to a torrent if you

remember a torrent file if you've ever

used one

it contains information about data like

files and folders that can be

distributed now if someone torrents a

file the folders and files within that

torrent are downloaded to the user's

computer but the torrents are

peer-to-peer sharing system they Mark

almost exactly like packet switching

does torrents collects packets of data

from wherever the data is available and

then reassemble it in the whole file on

your computer

in other words you can be downloading

information for the movie you're

torrenting or of course the movie that

you own that you're torrent and we

wouldn't want to say to do anything

illegal and what you're doing is you're

actually taking that information from

say 5 or 10 or 100 different systems

that are out there they're all coming

down into your system and then you're

compiling it all together

to make

one movie

this isn't unlike Willy Wonka where the

information goes up into the Wonka

vision gets split up into a whole bunch

of little pieces and then gets brought

back to you except all the little pieces

don't have to be sent from all the same

place

so the benefit of this is that it can go

a lot faster that's with packet

switching the downside of course is that

there's a good chance that the packets

can be lost along the way now the second

type of switching is called circuit

switching this method of switching

requires dedicated

physical connections so whereas packet

we're dealing with data in circuit we're

dealing with physical connections that

allow data to be transferred now it can

be difficult to establish these

connections but the results are a lot

more reliable than with packet switching

with circuit switching the connection

that's made is dedicated for that

purpose only in other words I create

switch over which all the data is going

to be sent once I'm done with that and

the transfer is complete I no longer

need this circuit and so it might be

switched to allow another computer or

system to talk to one another now

there's a very small chance of the data

getting lost or along the way because

the circuit switching establishes a

consistent data transfer however the

downside is I can't take it from say 10

different sources instead I have to have

one sender one receiver and in this case

because I can't split it up it might

take longer to find that one connection

although once that connection is

established it's a lot stronger so

here's an example of what packet

switching might look like the packets

that are traveling across the network

are all going on different paths right

one might be going like this

one might be going like this the other

might be going like this

etc etc

they're all going to reach the

destination on the right but they're

going to do so in a different way if we

say that this is the source

and this is the destination

this is going to alleviate traffic

Network because as you can imagine

I don't have to require everything to go

across this one

dedicated line instead it can use

whichever line has the least traffic on

it at that time and therefore

everything's going to get there without

with the least amount of traffic however

it's also not the most secure way

because obviously there are a lot more

points for someone to enter in and

perhaps steal information or sniff

information and this packet for instance

might have been gobbled up by a hacker

someone who wanted to get the

information or it somehow just got lost

so this is where the issues with packet

switching come in

now in the last module we talked about

many of the different transmission

technologies that Wan has in one of

those if you recall was ATM or

asynchronous transfer mode and imagine

that name asynchronous

that's important because it's not at the

same time it's asynchronous now ATM

splits data packets into these cells and

these cells again are 53 bytes in order

to send them now this made data flow

simple and it did not back up the system

and didn't cause too much traffic so

very similar to ATM is what we call cell

relay

so relay is a connectivity method that

breaks data up into equal size cells and

then sends them to the destination now

unlike ATM these cells aren't

necessarily 53 bytes but they're all

even with each other

so they're all sent across the network

and they all

are even meaning they each have the same

amount of bytes now the data itself is

transferred very similar to a method

that we just talked about in packet

switching the difference is that packet

switching doesn't evenly break up the

packs which could cause some Network

traffic so cell relay is good for

simultaneous transfer of data and voice

meaning it allows me to do voice and

data

at the same time however just like with

packet switching it's not very secure

and some of the cells could also be

easily lost along the way now as we all

know voice over IP has sort of taken the

World by storm international calling can

be really really expensive and so voice

over IP is a way to make calls through

IP packets or using the internet you

recall IP packets are part of the TCP

Suite they involve giving every single

device on a network and IP address which

is just like a phone number in an old

system and uh this would allow us to

save money on international calls it's

by far cheaper alternative to a phone

service because unlike a phone service

there are no monthly bills to pay and

there are no long distance charges to

deal with so VoIP uses the existing

internet infrastructure that's already

in place to make connections for calls

and what it does is it

basically puts the information from your

voice into packets and streams those

across a network now like almost

everything in Computing there is a

protocol that allows this to work and

that is called the session initiation

protocol

or sip

write that out

now if you see sip on the test or if you

see voice over IP on the test you can be

guaranteed they're related the other

thing you're going to see when it comes

to voice over p is called qos or quality

of

service the reason is we want to make

sure the quality is pretty good

otherwise if we're getting the packet at

the end you know if we're getting uh if

I say a sentence and I get the end of

the sentence before I get the beginning

of the sentence then the quality is not

really good and I can't really rely on

this so getting back to sip for a second

this is the protocol that's designed to

set up and maintain internet multimedia

sessions such as voice calls it's also

responsible for communication that's

used in video and audio conferencing

online games voice Chats on the internet

and so on so it's extremely important

and without it basically VoIP wouldn't

function

so here's an example of what VoIP might

look like as you can see there's both a

phone and a computer that are connected

to this network on the top end

PC connects through a modem or perhaps

even a network card

and the telephone connects through some

sort of adapter and they both connect

through the internet generally there's

also one box that everything sort of

connects into and that sends it out into

the internet out to your internet

service provider and again the important

thing here is that everything is being

captured into IP packets so your voice

is being turned into for lack of a

better term data in an IP packet which

can then be sent over the internet

great so now we've identified some Wan

connectivity options including a leased

line which is a line that you lease

between two places an example of that

would be that T1 or that T3 line the

reason it's leased is we don't actually

put it in the Telecommunications Company

does that for us we simply lease it for

a certain amount of time it's very

expensive and so a lot of companies

don't use lease lines unless they

require one what they use instead is a

connection to the internet and then they

will have uh basically virtual private

networks and software and other Hardware

that create a virtual leased line over a

public line we also talked about packet

switching which was important different

from circuit switching which is sort of

what switches do pocket switching would

allow me to send

data and if I had many different routes

for that data to take it could take any

one of those pack those those data

packets run in sort of any different

configuration I wanted it to and it

would all arrive at the enemy put back

together so the packets all basically

get broken up sent out

shuffled sent in whatever order they

need in the packet each packet has the

source and the destination and also it

has a number basically

so that way at the end it knows how to

put it back together in the correct

order this is somewhat similar to cell

relay the difference with cell relay

which is linked sormal to ATM is that

all packets

are the same

size

we also briefly which we'll talk about

more discussed VoIP or voice over IP

which allows us to make

phone calls or voice calls

over the Internet or using ethernet

technology the protocol that allows us

to occur is called sip or the session

initiation

protocol again if you see sip on the

test you can guarantee that it has to do

with VoIP or voice over IP now in the

net next lesson we're going to talk more

about remote networking obviously

something more and more of us need to do

with telecommuting and also something

that would allow us to replace for

instance a leased line with more of a

temporary solution

[Music]

thank you

welcome to module 9 lesson 4.1

practicals and services uh as usual

covering the things we haven't already

gone over

it's a wonder wide area network still

we're in brief I.E the stuff I think you

need to know because there's entire

books on some of these protocols PPP

PPP over ethernet

Dynamic multi-point VPN which has

actually just been brought into the

Cisco CCNA syllabus

sip trunks uh Josh talked about sip

trunks earlier

uh briefly it he actually wrote it onto

one of the slides when he talked about

voice so I'll just cover an extra little

bit

PPP very popular over dedicated and

circuit switch links for wide area

connection

now where the typical question you would

get certainly for Cisco is if you're

collecting a Cisco to a device over a

wide area network to a non-cisco device

what protocol would you use you'd

probably use PPP

because it's a vendor neutral anyone can

use it whereas Cisco has a their own set

of protocols that you can choose from

for your server-wide area networks also

works over many different link types so

synchronous ISDN asynchronous DSL Etc

two components inside

PPP you've got your ncps which show your

network control protocols these

interface with the TCP or network layer

talking about OSI and then you've got

link control protocols this manages the

data link sessions and connections

that'd be a typical exam type question

the other thing about PPP is it offers

authentication built in which is very

useful

now you've got two types pap

and chap

uh unfortunately if we go over to

password authenticate Authentication

Protocol

your password if you sniffed the packet

been sent over the line

uh the fields you would see

password it doesn't encrypt the password

chap

actually sends a hashed value

of

characters whatever they may be

so you don't actually see the password

so this is the one you're going to want

to use no one really is going to use Pap

anymore unless it's um you can configure

it if for any reason chap goes down you

can configure it's a it's called a full

back PPP fullback but really you'd

probably rather just have your PPP line

go down and you troubleshoot it

but search up is what you will want to

use because it offers the encryption

there's a three-way handshake this is

another typical exam question

um and you can see it in the diagram

here there's a challenge a response and

then it's accepted or rejected if it's

accepted then the line comes up and you

can pass then your data if um it's

rejected then obviously the PPP session

uh won't come up and I spent some time

debugging this when I work for Cisco

Systems

a continual authentication so it doesn't

just do it once I'm not sure you'd have

to read the RFC and see how it's been

implemented but there's regular

challenges take place during the session

uh usually there's a a host name and

password for example the host name of

this router is router B

and you would configure on this side

here you would say the host the username

that's permitted is router a and I've

just used a simple password so what

happens is this router's host name acts

as the Authentication

a hostname it calls using its um host

name here and its password and in the

database over here you've configured

that as the parameters that's going to

be permitted

you can do it in a lot more complicated

ways

the commands on a Cisco router are PPP

authentication chap uh or if you want to

use um and

um your clear text is pap

moving on to pppoe it allows

encapsulating PPP inside ethernet frames

no surprise really because the clues in

the name there often used with your DSL

connections and it tunnels to the your

internet service provider I'm just

thinking of questions of the last

because you're not going to have to

configure this so they may ask a

question what are the pppoe stage is

there's a discovery which is obviously

the um building up the connection

between the two devices and then the

actual session where the data is going

to be sent across the line

this is the same with most protocols as

you know

moving on to Dynamic multi-point vpm

this allows your remote VPN connections

to bypass your your headquarters VPN so

in your traditional

VPN service your spoke router over here

say

um say it's in Las Vegas this is in LA

and

um this is in

where can we have this Atlanta

a bit of a pain your branch office would

have to communicate to your headquarters

in order for the the tunnel to actually

take place but it'll be routed from here

to here and obviously if there's

problems in your headquarters office for

whatever reason or the line is congested

your connection won't take place so the

point of

um Dynamic multiple in VPN is your

Branch offices your spoke routers can

directly make a connection and it

bypasses your vpn's router

you do require a hub and spoke topology

which we spoke about earlier in our

topology

topology sessions

um oh that shouldn't be in there sorry

about that

left that in from my last slide

all right and finally I've got this

slide here this image from

um my

netphone.com.au this explains basically

how citrunks work especially an

initiation protocol if you ever hear sip

or a session initiative initiation

protocol which Josh mentioned you

immediately think voice over IP this is

what enables voice over IP to work

trunks enable your PBX to send and

receive calls via the Internet so what

it does is it takes your

um the phone your typical phone

connection

and acts as a bridge between the

internet

that's the

um the point of this the SIP trunk

so digital equivalent of a phone line

enables you to make and voice and or

video calls video conferencing calls via

the Internet

acts as a bridge between your PBX which

is your phone system that you'd have at

your um corporate office there and IP

telephony

all right so we covered a lot of stuff

but I think only what you need today and

it is covered in other presentations as

well uh by Josh PPP

pppoe Dynamic multi-point VPN and zip

Trunks and I've highlighted what I think

would be the typical exam questions so

that's all for now thanks for watching

[Music]

thank you

remote access remote networking

fundamentals

in the last lesson we talked about wide

area networks we talked about how they

can be implemented what their benefits

are how they transfer information some

of the Technologies we use and so on and

so forth now in this lesson we're going

to talk more about remote networking

access remote networking in wands

actually really go hand in hand and if

you think about it more of what we do

now more than ever allows us to remote

in from home to the Wan

the largest land in the world being the

wide area network of the internet and

then access

our lands at work this really allows us

to not only get stuff done but is

changing the landscape of how networking

the internet and security have

been created and how we continue to work

with them so we're going to talk about

this in this module and in the next

couple but for this one the first thing

we want to do is Define what remote

networking really is then we want to

identify some of the technologies that

we see in place when we discuss remote

networking these include VPN which we've

already discussed in some raw detail or

a virtual

private

Network

radius which allows us to authenticate

users once they connect and Tech acts

which allows us to keep its all secure

so these three are used in Enterprise

settings to allow someone to remote in

from home and connect to the network at

work

so wands are networks that are not

restrained to one single physical

location they're typically as we've

discussed many local area networks that

are joined together to create one big

Wham however this isn't the only

configuration they can have and remote

networking is something that ties in

really well with wide area Networks you

see remote networking is the process of

connecting to a network without being

directly attached to it or physically

present at the site in other words a

user or group of users can remotely

connect to a network without actually

being where the network is established

so if I were at home and wanted to

connect to a network say in China I

could actually connect as though I were

sitting right in an office in China

without actually physically being

present this type of thing comes in

handy quite a bit

now remote networking isn't always

happen between two very distant

locations in fact it can be used within

the same building the same room while

traveling and remote networking not only

works on a long distance level but on a

local network as well for instance

suppose that I'm an administrator in my

office and I want to access the contents

of a user's computer where I want to

restart a server well instead of having

to get up walk up to the fourth floor or

down to the basement wherever the server

is I could simply remote in to the

server and reboot it from there so you

can see that it's a huge time saving

device however it also opens up a lot of

possibilities for security issues and so

on so here is an example of what remote

network connectivity could look like the

user is in China on the right and they

need to connect into the network in New

York here on the left so they're sitting

at one physical location and they

connect through a Wan which we're going

to called the internet the largest Wan

in the entire world and they remotely

connect in some sort of way which we'll

talk about usually through something

called a VPN using all sorts of public

networks and eventually they reach the

router at their corporate office

and then it's as if they are actually

sitting there connected into the network

they can now access resources on local

clients or even on the server and all

without physically being at the location

in New York now there are a lot of terms

we hear when we talk about remote

networking and remote access most of

them end up being acronyms for the sake

of time and convenience but there are

three that I want to specifically talk

about here that we're going to talk

about in more detail in the coming

modules the first is VPN or virtual

private network is this something we've

talked before and we'll talk about late

a little bit later but in essence it

extends a lan or a local area network by

adding the ability to have remote users

connect to it the way it does this is by

using what's called tunneling it

basically creates a tunnel in a through

the wide area network

the internet

that then I can connect to and through

so all of my data is traveling through

this tunnel between the server or the

corporate office and the client computer

this way I can make sure that no one

outside the tunnel or anyone else on the

network can get in and I can be sure

that all of my data is kept secure this

is why it's called a virtual

private Network it's virtual it's not

real it's not physical it's definitely

private because the tunnel makes sure to

keep everything out now the next term we

want to talk about is called radius

radius by the way stands for remote

authentication dial in user service I'm

going to write that out here remote

Authentication

dial

in

U-verse user service now if you notice

there's a dial in well remote can

actually be uh

dialing in using a modem we don't use

that much anymore but this is an older

service what this does is it allows us

to have centralized authorization

authentication and accounting management

for computers and users on a remote

Network

in other words it allows me to have one

server that's going to be responsible

and we're going to call this the radius

server

that's responsible for making sure once

a VPN is established

that the person on the other end is

actually someone who should be

connecting to my network remember I

don't want to just let anyone connect I

want to make sure the person who

connects is someone who belongs to my

network generally what we'll do is we'll

have active directories

which is what Microsoft uses

to create for instance usernames and

passwords and we'll link that up or sync

it with the radius server sometimes this

is done on a separate um a separate

server sometimes it's done on the same

server either way once you connect the

VPN the VPN then goes to the radius

server the radius server checks the

active directory and now I can make sure

that only users of the network are

allowed onto my network

finally we have something called tacax

or terminal Access Controller access

control system it's really long I'm not

going to write it out this is actually a

replacement for radius there was another

replacement for radius by the way it was

called diameter and if you're a math

whiz you'll notice that radius is half

of a diameter when we talk about circles

but diameter wasn't really used much

tacx on the other hand is a security

protocol it allows us to validate

information with the network

administrator or server and the

validation is tested when we try to

connect just like with radius of course

the benefit is tacx is newer

and

more secure than radius so it basically

does the same thing it's just a little

more powerful

all right so this was short but I just

wanted to give us an overview of remote

networking and we're going to talk more

about that in the coming modules so we

talked about remote networking what it

is allowing us

to access a lan

basically through

a Wham whether that Wan is the internet

or public switch telephone Network it

also allows us to access the LAN

from a different

physical

location

we can also identify three remote

networking Technologies the first

virtual private

Network

creates a tunnel

over the win

through which we create a virtual

Network that is also private we also

talked about radius and tachs both of

these allow for authentication so we can

make sure the person who establishes the

VPN is actually allowed on our Network

[Music]

thank you

remote access remote access and

implementation

we've now talked about some of the basic

information when it comes to remote

networking and with that base knowledge

it's going to come into play in this

module we're going to talk more about

remote access and how to implement it

some of the stuff we're going to talk

about is overview and some of it is

still pretty basic again you're not

going to take this information and just

Implement a network or remote access to

a network that would take a little more

leg work and a little more research what

this is really giving us is an overview

of how it all functions and what you

need to know for the exam so we're going

to talk about remote access as opposed

to remote networking remember remote

networking is sort of the act of

creating the network to allow remote

access so we're going to talk about what

it is what it does and the benefits for

it we're then going to discuss the steps

of implementing a remote access policy

or remote access Technologies

so remote access is a practice that's

extremely useful and becoming more and

more popular constantly All Around the

World in every I.T situation as we've

mentioned it's a way for someone to

connect to a corporate land from outs

from an outside location it's not always

used in a corporate setting but for the

most part that is its main use however

for instance perhaps you wanted to

remote into your home network or a home

computer from the office or you wanted

to remote in from outside your home

these are things you could set up as

well

with remote access you then have the

ability to connect to a physical Network

without having to be anywhere near the

network in fact you could be on the

other side of the world and still

connect as though you're sitting at a

desktop PC on your land now you can

imagine how this is even going to take

it to another step where we could start

to have computers that are on a lan or a

land that we don't even control or have

any physical access to at all instead

all of our Computing will be done

remotely this is already coming into

play when we talk about cloud computing

and things like Amazon's elastic cloud

which allows you to set up a virtual

computer on a remote system and then

remote into it and through remote access

and connect to it just like you would be

connecting to the computers though you

were sitting in front of an actual

computer now this obviously speaks to

not only a greatly reduct reduced amount

of cost but also a lot more flexibility

because now I can set up a computer

anywhere in the world and for instance

if I had 20 computers I could remotely

access them and I would only need one

monitor keyboard and mouse

so you can see where this is really

going to come into major play

now we've already seen this before but

here's another example of what remote

access might look like I'm at home and I

want to access the office computer so I

connect through the internet to the

router over at the office through

something called a VPN

and now it says though I'm sitting there

working at the office in fact if it

wasn't for the fact the boss had to see

my face they would think that I was

actually there

so the first step in implementing on

remote access is assessing it we need to

before we can set anything up we need to

know what exactly we are going to set up

so first you need to review and

determine all the connections that are

going in and out of the Lan this means

deciding how remote users are going to

connect to the network for instance if I

want someone to dial in directly they

could use a modem this is going to go

over the public switch telephone Network

or pots the

plain old telephone system alternatively

let's say I have a T3 connection

connecting to corporate Lan out to an

ISP well then as long as people at home

have internet access which today they

basically would and most of them have

Broadband access they'd be able to

connect back through their ISP to the

network

second we have to understand know

exactly what applications and systems

they're going to need for instance I can

give them access to their computer which

might be one way to do it but if I have

a lot of people logging in constantly

remotely and I need to give them access

to their computer that's going to be

pretty difficult to set up and quite

um

uncentralized so what I might do is

create one remote access server RS in

which uh everyone can connect and get

their profile or information this also

goes with something called

virtualization or

cloud computing so basically they would

log on to this very powerful server and

they would see what looks like their

computer in fact if I was basically

doing this all the time I might just do

this for when they sit at the office

they just sit at a terminal sort of

thing turn on the computer and they're

connecting actually to a server that's

not even located in the building

finally I want to determine the number

of remote users if I'm only giving this

to say uh the top hun shows at the firm

that's one thing that's going to be for

everyone in the entire operation I'm

going to need to spend a lot more time

and resources devoted to setting up

remote access

now the next thing I have to do is think

about the considerations and the things

that are necessary for remote access in

order to implement for instance the

first step is to make sure that the

remote access solution you create is

flexible enough to support all those

connections and the users that are that

you've just established for example if

one remote user is connected to a T1

Line and other ones can't get through

dial up your solution is going to need

to be able to accommodate both of them

of course nowadays that's not such an

issue because everyone has

um Broadband connections but if they're

not connecting in the same way or one

person is going to be connect traveling

around while most people are going to be

coming from home well and those are all

things I need to take into account

next need to establish some sort of

centralized access point meaning when

they hit that router uh if they're

coming out of the internet into the

router I need something here that is

going to centralize all of the stuff

coming in I also don't want to just give

them access to the network I might want

to send them into a separate

Network temporarily while I make sure

that they get authenticated perhaps a

virtual Lan or a Honeypot or something

so it's important or demilitarized zone

so it's important that I have some area

where they can go and understand what

the central device is going to be in

some cases we could call this a VPN

concentrator

which is basically a device that helps

set up vpns finally I need to consider

security when I'm establishing this

remote system as I mentioned I don't

just want to give people access to the

network I want to make sure the people

on my network connecting wirelessly or

remotely or physically connecting can

all connect securely I don't want

someone to tap into their connection on

my end or on their end so it's really

important we take security into account

nowadays we have a lot of uh

authentication methods that would

provide you with say a key ring and on

that key ring you'll have it what's

called a token

the token provides you with say a six

digit number that randomly alternates

every minute unless you have the token

and that token is set up with your

computer you won't be able to get access

to the internet these things we've

talked about in a plus but I'm just

reviewing them a bit more

now I also need to have some procedures

and policies in place so that people

understand how they're going to be able

to access and what they're going to be

able to do

the policies ensure that the procedures

are followed and the procedures ensure

that the safety is used when remoting

into the system so designing these

policies is up to the network

administrator and perhaps this Central

information officer or the CIO or the

Chief Information officer now it's

common to have a system configuration

that does not allow users to remotely

access uh the system after a certain

time at night I might want to do this

for a number of reasons however the

policies need to be whatever they are

well documented and easy to understand I

need to know exactly how I'm going to

access stuff otherwise what's going to

happen is you're going to say hey we

have remote access and suddenly people

are going to start calling the help desk

saying it's not working properly

we also want to make sure that they're

accountable if they don't follow

specific rules policies Etc so I need to

say if someone remotes in or loses their

token they could be possibly fired

because that's a huge security breach

just like I don't want to give my laptop

or my token to someone even if it's some

within the network if I've been told

specifically to keep it same with

passwords usernames basically the idea

is the more ability I give people the

flexibility I get people to connect it

also makes it much more of a security

hazard

finally you need to make sure Human

Resources is behind all of your policies

they're the ones who are going to be

training everyone and so if HR isn't

behind you you're going to be in major

issues and they're going to fight you

the whole way speaking of Human

Resources I bet it's pretty fair to say

that not everyone is going to be

qualified or knowledgeable to enough to

connect to remote access so it's really

important that we train the end users on

what's happening on their end and how

the connection works it's a good idea to

have the remote users learn about what's

actually happening when they connect and

how to set up their ends of the

connections otherwise your help desk is

going to be inundated with calls and not

only that but you're gonna have a lot of

people upset when things aren't working

properly even if it's something that

they could easily fix

so like the job of an admin in any other

case it falls upon your shoulders to

help users when there's any sort of

issue this will become a lot more

difficult when the admin doesn't go over

to the user's desk and help them out or

doesn't have the time to go over

hundreds people desks you have to

connect with the user in some other way

though perhaps it's through a handout or

through an email or perhaps you remotely

access their computer or even give the

computers to them set up already to to

remotely connect or talk to HR about

creating some sort of training program

that's going to help support all of this

finally once we've set all this up we

need to monitor the network to make sure

the remote access is working as intended

the first step towards doing this is to

manage all of the entry points that any

of the users could use it should be kept

down to one single access point and

that's important because obviously it's

easier to manage one access point than

several father users enter the network

in the same place it's going to be a lot

easier to monitor them

next we need to make sure that the

policies and procedures are followed so

when users start using wrong procedures

don't follow the policies there's a

really good chance something's going to

go wrong and it's important to have the

remote users follow a strict procedure

in order to avoid any problems and to

help take the load off of you and the

help desk

it's also very important to understand

everything that's going on within the

network you have to know where the

connections are what they're doing what

the users are up to you have to keep

track of all of this stuff and there are

different ways to do this different

devices we can deploy and software that

we'll talk about

so just to recap we've defined what

remote access is what it is what it does

and its benefits all in all it allows us

to again be geographically at a

different location

and connect

to the lamp

we also talked about lots of the steps

of implementation and although this

isn't very technical all this stuff

comes up on the network plus exam you

have to know what it is you're supposed

to do so remember we talked about some

policies procedures

[Music]

training

and monitoring

now in the next module we're going to

talk more specifically about how we set

some of this stuff up and what we're

going to do to make sure it works

properly

[Music]

welcome to module 10 lesson 2A a remote

access methods

so remote access is all about how you

can reach various network devices when

you're not at the physical location

look at RDP SSH VNC

telnet management through the https

and file access and then outer band

RDP this is uh proprietary to Microsoft

so they've come up with this software

you may have seen it before when you can

um if you check on your Windows machine

you can normally

and find the uh

the button to click that it will allow

you to connect to a remote computer and

you might use this if you work in a harp

desk if you need to support a remote

user

you can have remote access and control

via screen sharing

this is actually how a lot of scammers

will

get people to hand over remote control

they'll phone somebody who's a bit naive

and say um we've found a technical floor

in your computer and Handover can you

hand over access so we can fix it

typical exam question would be what port

does it use it's TCP it has to be

reliable obviously and the port is three

three eight nine

you need to know this kind of stuff if

you need to permit this through your

firewall

or deny obviously

now the client side can be Windows Mac

or Linux there's a few different

operating systems that are supported

SSH

this allows remote terminal access by

terminal we mean a window like this

where you've got command line access to

a remote computer server

or in this case I'm not sure what this

is actually it could be a Cisco device

of some sort

it encrypts communication between the

endpoint so most places now you can't

tell Nets across the network

you uh because it's all traffic is sent

in clear text you have to use secure

shell as part of the policy the network

policy

in order to use the Kershaw you have to

enable it on your server router or

switch it isn't usually enabled by

default

the client software you install on your

computer

the one I use mostly to get my remote

secure uh shell sessions is putty it's a

free download if you Google putty I

think it's pretty.org you got to you get

taken to

BNC I used this a while ago when I was

at holiday and needed to connect to my

work computer this is platform

independent it's a GUI based

which is pretty handy if you're not too

familiar with command line desktop

sharing it uses remote frame buffer to a

remote controller computer

all right you get the TCP Port basic uh

the port is um 5900 and then there's a

number the number will you check the

documentation but there's various

numbers you will be using depending on

what you're connecting to and how you

want to connect

now telnet is uh TCP protocol is used

for remote access I did mention SSH so

really tell net you'd use it at home if

you've got a rack or something you want

to troubleshoot you would never use this

in a corporate environment now you'd if

you went and did some configuration or

network installation for a company and

left town to open then I think you're

probably

um be in trouble legally because you've

left a big hole in their Network for

other people to connect

it requires client software just uh

something like putty used to have hyper

terminal with a Microsoft they stopped a

bundle in it with the software I think

um about four or five years ago

you could still enable it but you had to

go into the back end and um I think you

have to download some extra software but

um it didn't work it doesn't work too

well anyway uh uses TCP Port 23 make a

note of that all traffic isn't encrypted

not secure which is why we don't

recommend you use it

I've already mentioned this bundle

blocked

https management

this gives you the graphical uh access

method for a device when you first buy

for example a Cisco router and say you

don't know how to configure it you can

get the router you basically plug in an

ethernet cable here

you connect your

PC or laptop and in the documentation

that will come on a CD-ROM or you get a

little card it will basically say in

your browser window you put

HTTP possibly https and then you will

put a number so say for example your

home router will normally be something

like this 192.168.0.1

and then that will result that will

resolve it doesn't need to use DNS

because it's uh the using an IP address

it will resolve them to this management

window and on my route up on my home

router you've got a whole bunch of menus

here you can configure the firewall you

can reboot

you can check your DNS settings you can

permit or deny different devices if you

want your kids to access the internet or

you want to block them and you can you

can configure that

um

firmware etc etc anyway you get you get

the idea so this is your way of managing

your device it's a security issue if

enabled by default

I'm trying to remember now I think uh

Cisco devices is disabled by default but

sometimes you can have different

versions of iOS

where all enabled and then there's

something there's some change happens

and the command changes or the default

setting changes this is for routing

commands security commands how to switch

traffic packet switching and track and

frame switching

so um check what device you're on and if

it's enabled or disabled by default

generally you'll want it uh disabled

otherwise you've got to configure

Advanced usernames and passwords so put

the IP address into the browser bar

remote file access

FTP is used to upload and download large

files in securely

so this represents a problem

SFTP this is a protocol in its own right

so it's not as if you've got FTP and

added something to it this is its own

protocol

so just be careful it's encrypts a

secures an eclipse traffic it uses SSH

which is port 22.

so um don't think that it's an FTP with

some little extra bit on here

security bit security issue if enabled

by default this is um again I've done

that again sorry I've left it from the

last slide

your other file transfer method is

Trivial file transfer protocol which I

think we've mentioned earlier if you've

got a small file that you want to send

over your network again please don't use

this this is just what it's used for if

you've got a router and you want to back

up the configuration you've got a tiny

little file like about

a by uh eight bytes whatever or eight

kilobytes probably

um you'll you'll back it up here using

tftp

but again this file really is sensitive

because it's got IP addresses passwords

and heaven knows what so really using

tftp it shouldn't be done anymore if

you're at home you've got your little

home network and you want to have a play

with your software fine and if you're in

a corporate environment no I I think

it's a really bad idea

out of band access outer band basically

um

it's not within your normal ethernet

connection

so say you've got a router you've got a

fast ethernet port here and then you've

got your again your PC or whatever you

use to connect

so this will be your in-band

out of band would be something like a

modem connection so you've got your

router

and your

your you've got your telephone

connection here and then a modem

which is connected to your computer so

out of band

used for emergency access normally if

you're connecting out a band something

has gone wrong

now it looks like this is a modem here

and you can connect uh over the Internet

so you could connect to the modem and

then there's a a modem Port here

normally on Cisco devices it's got aux

written on it again check your

documentation because things change over

time

so attach your mode and support what you

would normally do is this wouldn't be

connected say you're in a corporate

environment so this is in your corporate

Network

and you've got a um

you've got your remote hands so this is

like your help desk team they're not

they're not that technical say they're

level one but you've got people who if

you send them in the instructions to go

to rack

one and

um find

say Row three or whatever and ask them

to plug in the cable and you'll have the

cable sitting there but not plugged in

you'll do the fix bring the router back

up so all the other ports are working

and then they will disconnect that again

and you'll normally have obviously a

ticketing system of some sort where

you'll say plug it in and then confirm

that they have unplugged it because it's

a security

um issue so just be careful

so I've mentioned remote hands um you

can use a console oh you can use a

console router for multiple out of band

devices so say you've got this is

normally we used to do this when we were

practicing for Cisco exams you out of a

rack of all of these different routers

say router 1 router 2 router 3 switch

one

switch to and you haven't got ethernet

access for whatever reason so what you

do is you'd have this uh a console

router I can't fit it all in a console

router

which basically connects to the console

ports of all these devices now console

connections don't work over the Internet

it's an out of band thing so what you

would do would would tell net to this

device here

and then through this router here it

would have the telnet the software the

client software that you could configure

all of these devices through a command

line

and um really handy way of connecting to

remote racks but you could have this for

your corporate Network

this is an example of one this is a the

the models of routers for Cisco are 25

11 and 25

21. now you can see how old this is this

is your ethernet connection look at that

the aui

so what you do we've all we've talked

about transceivers already you think but

you'd have this transceiver that's got a

an ethernet port in here so you could

connect an Ethernet cable to another

device which then lets you get in at 10

Meg

um so pretty slow uh old-fashioned

serial connection there I said db60

and then your console port for console

connections this is your modem I've

talked about

your uh for your outer band access

and what this is is a bunch of console

connections so you can see one here

they've all got numbers on

and it's numbered one to eight here and

then if you plugged in the second one if

you needed um up to 16 devices then

these numbers I won't tell you how to

configure it I've got a video on YouTube

if you want to look that up under my

name Paul Browning

and you could connect these from a load

of other devices so really what you were

doing is connecting to this device

whatever this modeler switch is

but you're doing it you're telnetting or

get all rem or connected through a modem

connection to this device and then from

here you're choosing whatever console

line is free so for example one and then

you can actually configure this device

so it's a slightly longer way of doing

things but

um that saves you having to configure

tile net connections

to 16 different devices so pretty handy

so we covered a load of stuff RDP SSH

VNC telnet

https for your GUI uh

access here file access and then outer

band so it covered a lot of stuff so

thanks for listening I'll see you on the

next presentation

[Music]

remote access

vpns and their protocols

in the last two modules we discussed

remote access and remote networking both

are basically around the same concept

remote networking meaning that I can

create a network that exists in two very

different geographical locations and

remote access meaning that I can access

a computer or a network from one

geographic location to another so

they're both basically the same thing

but how we accomplish this in a secure

fashion is what we're going to talk

about in this module and that revolves

around this term VPN a VPN I've talked

about a bit in the future in the past

rather and it stands for virtual

private

Network and as that term implies and

like we've discussed it creates a tunnel

through the net the internet the wide

area network in which we can securely

send uh data between two locations and

why the tunnel well that's what keeps it

secure and private from everyone else on

the internet and this is how we've been

able to allow remote networking to

become so ubiquitous in our world

because I no longer have to have a

direct T3 or T1 line between my office

and my home instead I can use the

internet which is fairly ubiquitous

these days and create a virtual private

Network again virtual being the key word

there because it's not actually a

private Network it's a virtual private

Network because of this sort of

tunneling concept that we're going to

talk about

so what we're going to talk about in

this module is first to Define virtual

private networks a bit more and then

talk about the different scene of VPN

client and VPN server we've seen the

terms client and server in the past so

these shouldn't be too new for you

then I want to talk about the VPN

protocols there are two specific ones

that you need to know about for the exam

one is called pptp and the other is l2tp

notice the T in there for tunneling

so we're going to discuss both of those

and how they all work all right so first

virtual private networks a virtual

private Network or a VPN is is nowadays

an essential part of networking it's

basically used anytime a network is

extended Beyond a lan or local area

network so it establishes a remote

connection through a public network such

as the internet in order to extend the

Lan and I'll show you a graphic of this

in just a second once the extension is

made a dedicated point-to-point link

point

to point link which you might also have

seen P2P a dedicated point-to-point link

is created between two points using the

same IP network meaning that even though

we are on two very different IP networks

I might not be on my land you might be

on yours we can create a virtual

point-to-point connection between the

two using tunneling that makes it as

though we are on the same point-to-point

network the same IP network and I'll

show you that in just a second now the

extension of the Lan are sometimes the

linking of two lands

creates a new wide area network so you

could say that anytime a VPN is

established

and a new land sort of added on a new

Wan is created don't worry too much

about that concept but the idea again is

if I have the office slam

and let's say either another office

and then perhaps a remote user

all connecting through VPN

over the internet

I now have created an effect

a wide area network out of three very

distinct local area networks but I

haven't used any different

infrastructure than something that was

already there

now vpns are actually a type of remote

access probably the most popular one

they share similarities to all the

different remote access for instance

you might think of dialing via modem but

vpns are inexpensive way to extend your

network because it uses the internet so

you don't need to purchase a leased line

service now remote users just Connect

using the VPN to their remote office

through the internet

and so that's really the key here is it

uses the internet as its platform

so

this is what access through a VPN might

look like the remote users

connect let's say from home through the

internet and then there is a

authentication server that verifies that

this user is allowed on the network once

you pass through that it puts you into a

switch which then makes it as though

both of these computers

are on this LAN

so in effect I've created a new Wan

without having to lay down any extra

line because I'm again using the

internet now

say that this was an office building

it could have an office building here

perhaps another one and these can be any

place in the world

and because I'm using tunneling through

the virtual private Network

I create an effect a tunnel which allows

all of these to each create a

point-to-point connection

between themselves and this

authentication server that then

basically puts them

onto this Lan so any one of these

offices is now part of

the land and in effect then making a

brand new Wan or wide area network

now there are a lot of things we need in

order to set up a VPN connection and

some of them are

more important than others but I'm just

going to key in on the the main things

we need

first we need a VPN client now the

client is the remote access user without

this user there's no point in setting up

a VPN so why bother if no one needs to

connect they are one of the most

important clients or the ways that we

components rather and what's interesting

about a VPN client is it can either be

software

or Hardware

if it's software then it's

built into the operating system

generally or into the networking package

of the operating system if it's Hardware

it's generally either built

into the router

or it's a separate device

which is generally called

VPN concentrator

now the benefit is

if I have for instance two offices

we'll call them office one and office

two and they are located in different

parts of the world

but they both connect to the internet

then I don't want each so let's say each

of these offices has we'll put four

users for now but let's say these four

really represent 4 000 users I don't

want each one of these people to have to

set up on their computers a piece of

software that's going to allow them to

connect

through this tunnel so instead what I've

done

is I do something on the network side of

the office for instance in the router or

with a device that automatically creates

this tunnel between the two offices

and then these members don't have to do

anything now if I am a lone user at home

then I'm probably it's going to be

easier for me instead of buying a device

that's going to allow a network to

always set up to just plug in through my

computer and put it into the software

whenever I need

and if I go into Windows 7 real quickly

go over here into

our Network and Sharing

and say we were going to set up a new

network you can see right here it says

set up a VPN connection and if we go and

do this you can actually connect to a

workplace now connecting to a workplace

what they really mean is setting up a

VPN connection so I'm going to click

next

now you can see I can either dial

directly which is something that we

might have done years ago or one the one

we're going to use more likely now is

the through the internet connection

again creating that VPN

we could call this whatever now one

thing we would need here is the server

address we'll talk about that but why in

just a second but we are the client and

we need to connect to a server so this

is where for instance that

server address is going to go now you

know this IP address wouldn't work

because this is a private IP address but

we're just using this for the time being

right here you can use sharing Etc but

for right now let's just go ahead and

click next

let's say our username

so let's say user and then we have a

password I'm just going to do password

we can have it remember the password or

not you might have a domain if you're

connecting to a Windows computer and

then you click connect

the next thing I need obviously is

something for the VPN client to connect

to and this is the VPN server the VPN

server not only allows the connection to

take place but is also going to

authenticate

the client and allow them to connect

now this might be done through again

some sort of device like this VPN

concentrator I've mentioned or through a

separate server that has software hooked

up on it either way I need some sort of

device

that allows

outside

clients

to connect in to the network basically

to give them permission act as sort of a

a controller or or a Gates person

uh there are different ways of setting

this up and you remember I mentioned

something called an Ras remote access

server and the specific one we mentioned

previously was a radius server

which was a remote access dial-in uh

server and

although this was for dial up it still

does the same thing which is it allows

someone to remotely access the local

network so we have some sort of Ras and

again an Ras stands for let me just

write that out remote

access

server

now the access method is also pretty

important without a connection there's

no way for a user to get onto the

network so most of the time this

connection comes from the internet but

it's not uncommon for a VPN

implementation to actually come through

a private intranet as well so we have

the internet which is the public version

but there's also something called the

intranet if you recall the internet is

like a private internet and sometimes we

might actually have a private leased

line or we have several different sub

networks within a larger Network and so

it's important to know where your people

are connecting from most the time you're

not going to see the intranet it's all

going to be through the internet and

sometimes you'll also have people

dialing up so it's all important to know

even though internet is the most popular

sometimes we're going to be doing it

internally through an intranet and

finally there are two protocols that we

need to know about and the generally are

set up on the server side and the client

needs to be configured to set up through

the first is PP TP which we're going to

talk about in a minute and this stands

for

point

two point

tunneling

protocol

the other is

l2tp which stands for Layer Two

tunneling

protocol

and if you remember talking about the OS

and I and the tcpip models that's what

that layer 2 refers to

so let's talk a little bit more about

these protocols the VPN Protocols are

really important to the security and

efficiency of VPN so the protocols

manage establish and secure the data

that's going on through that VPN

connection so pptp and l2tp are the two

most common protocols that are out there

they function pretty differently but

their jobs are fairly similar they

enable

encryption

which means the data isn't sent in its

sort of plain text format it's sent in a

way that if you were just to see it it

would look like it's all gobbley

and so what happens it's set on one end

in a code and then received and decode

on the other end and it also provides

authentication so only those who are

allowed on the network actually get on

the authentication it also establishes

the identities of the people in the

network so we can audit them it's a way

for the clients and the servers to be on

the same page about who is on the

network

and like I mentioned encryption is

really for the data protection so

because we're going through the internet

which is public this is really at risk

for attackers and so the encryption

protects that data that's traveling

through the network and prevents these

issues from happening generally speaking

we're going to prefer l2tp over pptp

just because it's a more advanced

protocol and uses a different form of

encryption

I think in fact

Windows 7 and Vista only allows lttdp

now it doesn't even allow pptp as we

just saw when we looked into windows

all right so just to recap what we just

talked about first we mentioned virtual

private networks which you'll never see

referred to as virtual private networks

you'll see them referred to as vpns and

those basically create a tunnel

through generally the internet sometimes

the Intranet

to connect

lands together and in effect then

creating one large Wan now this can be

done between office and office or say a

home user in an office and either way

you have a VPN client which would be the

one connecting to the server and

remember we have either software

or Hardware we looked at the software

that was built into windows we also have

Hardware the generally the thing that

you'll see with there is something

called a VPN concentrator it could also

be for instance built into your Soho

router or be built into a Cisco router

of some sort as well we also discussed

the two VPN protocols remember these

were the point-to-point tunneling

protocol and the layer 2 tunneling

protocol notice that these both you know

are VPN protocols because of this T the

tunneling protocol generally speaking

we're going to see l2tp used more than

pptp and what these really are

responsible for is defining how

encryption takes place

and authentication which is something

that works in conjunction with the VPN

server to accomplish

[Music]

welcome to module 10 lesson 4 gra SSL

VPN and VPN concentrators

we look at them

secure sockets for VPN also

what is SSL

VPN concentrators ipsec this is just an

overview

as usual there's a whole entire um exams

for security stuff like this in more

detail like the CompTIA Security Plus

which we host on howturnetwork.com and

the CCNA security also

GRE stands for generic routing

encapsulation and it was actually

developed by Cisco Systems as a

tunneling protocol and I totally in

protocol tunnels something else another

Prodigy call within a protocol

so it allows Network users to access the

network service it's not supported by

the underlying Network so you can

actually tunnel

um lots of different things you can sort

of IP version 4 inside IPv6 if the um

hop by hot pair devices don't support it

here is an image of a GRE tunnel going

across an internet

Source interface or IP address

destination IP address of the tunnel an

IP address of the tunnel that's part of

the configuration you don't really need

to worry about that

but the traffic will pass through the

GRE to Norm

and the device is actually sending the

traffic will only examine the header of

the GRE packet which is um wrapping the

uh the traditional IP traffic

so we already know we can run a protocol

every Network you can actually run

non-routable addresses as well so inside

that tunnel you could have a 192 address

and as long as the tunnel is going via

routable IP addresses you'll be fine

a gra creates a virtual point-to-point

link and encapsulates a variety of

network protocols

uh

yeah I've already mentioned the private

IP addresses it's used in conjunction

often with pptp point-to-point tunneling

protocol and ipsec if you want to create

a VPN and there's an image there for

with the GRE tunnel also working with an

IP sector null from networkstraining.com

uh VPN

a virtual Network a virtual private

network is a full term it's built on top

of an existing public network obviously

very handy if we need to securely

connect over the internet from

um two different network locations

often used by companies because they

don't want to buy a dedicated lease line

so they'll just use existing security

technology

you have a secure Communications between

two private Networks

SSL VPN this is a secure sockets layer

virtual private Network

it provides encrypted communication

between a clients and server one example

is SSL equips communication between a

web browser and a web server and your

browser will be a Google Chrome or

whatever you're running on your laptop

or PC

the user connects to VPN devices using

their web browsers traffic between the

web browser and the VPN is encrypted

with the SSL protocol

so as a result you've got a secure

access to web applications and client

server applications

you'll see this working with the um

green padlock when you're browsing

different websites built into all

standard web browsers you'd have to add

anything extra on you don't have to

configure or install any client software

anymore you used to have to that was a

few years ago now and it's all built

into the web browsers

uh the SSL VPN can be accessed from

anywhere including airport hotel rooms

coffee shops as long as you've got web

connectivity and the user has a standard

SSL client that's used with that

particular SSL VPN

uh SSL VPN products usually Standalone

Hardware Appliances and other software

Solutions available speak to uh whatever

the whoever the sales representative is

for Cisco or whoever you're using for

the technology

you also get common security services

such as authentication encryption

Integrity protection Access Control who

can access

even how long they can access for

security and endpoint security controls

in choosing prevention IPS

authentication as we know I'm sure is

just authenticating that particular

person to verify they are who they say

they are encryption encryption protects

the con

confidentiality of the data as it passes

through through the internet

Integrity ensures that the data is not

altered so

um there's a whole bunch of ways to um

showing and offer Integrity of the data

as it's sent from the source and

received at the destination

Access Control gives restricted access

and that can be based upon a number of

things and the access control is then

associated with whatever privilege is

you wanted to give that particular user

the endpoint security controls checks

the user system for compliance whenever

the user attempts to use the SSL VPN

intrusion prevention checks the data for

any Potential Threat after it's been

decrypted

VPN concentrators these were supported

originally when I worked at Cisco by the

security team

they provide a remote user with secure

access to the organization's resources

and the concentrator is basically an

endpoint for multiple VPN connections so

there's maybe lots of Home users or

people dialing in and

Mobile sales people that need to connect

from certain places and the VPN

concentrator will be the point where

their connection is terminated

all right uh the concentrate is a device

it can handle multiple tunnels coming in

a VPN they provide VPN encryption either

by using ipsec or SSL

again check with your vendor for

documentation

ipsec is IP security provides a high

level of security and encryption and

because client software to establish the

VPN tunnel

ipsec is better for fixed locations SSR

when the remote users need to connect

from various locations for example

they're a traveling salesperson

and nowadays VPN concentrators are not

manufactured as separate devices they

normally combined with devices that also

provide firewall protection if you go to

cisco.com and then click on I think it's

sales or products you'll see the type of

devices that are available and what they

do

all right so we've covered a fair bit

GRE tunneling VPN SSL

Security Services of SSL VPN and a VPN

concentrator on ipsec

that's all for now thanks for watching

[Music]

Network management Network

Administration

in the previous lessons we've talked

about a lot of the technical aspects of

networking including remote networking

remote access virtual private networks

local area networks wide area networks

and so on there's someone who's required

to sort of put all of this into place

and that's where an administrator comes

in so in this lesson and in the

following modules I want to talk about

what an administrator is and some of the

tasks they have to do in this module in

specific we're going to start by

defining an administrator or network

administrator now there can be several

administrators at any one's site but

we're going to give an overview of what

an administrator no matter what their

specific role is going to do then we're

going to identify some of the key admin

duties and these might be documentation

and monitoring we'll talk more about

these in further modules and we've

probably already mentioned already

mentioned these to some degree so some

of this might be recap in some cases it

might be overview but a lot of what's on

the network plus exam is is sort of

applying not just having knowledge but

applying the knowledge in certain

administrator roles since that's what

they assume you're going to do with your

certification

so there's no doubt that we have used

administrator or admin for short

in uh hundreds of times by now so it

might be useful to stop for a minute and

actually take time to talk about what

this term means so the administrator of

a network is the most important person

involved in network it they are in

charge of everything that happens on the

network and know what all of the users

are doing in charge of security and they

can be held responsible for everything

that happens on their Network so not

only are they responsible for sort of

creating the network but if someone

misuses the network the really acts is

going to fall on them more than that

they're in control of all the accounts

the resources the data that users have

access to the administrator is the only

person that has access to everything in

the network and can control what others

can access even if they give access to

say an assistant administrator in the

end if that assistant administrator

screws something up it was the

administrator who gave them access in

the first place so clearly this is a

really important person and are

essential to managing and monitoring the

network without them there really

wouldn't be anyone with enough knowledge

or ability to manage how these networks

and you can see how large they get

sometimes

so here is essentially what an

administrator's view might be like they

have a view of everything that happens

going in right they know all of the

nodes all of the servers and this is

very simplified all of the routers and

switches this is what we might call a

network diagram we might also have

printers

and if this is a cloud environment as it

seems to be then they're going to be

aware of all the virtual sort of stuff

that is set up

they're going to beware of all of the

user accounts

the network security

they're also going to be dealing with

all the remote access

if there is this going out to the

internet are there firewalls

are there intrusion systems etc etc so

they really have an overview of

everything they have to maintain

everything as well you can see how

complicated this can get which is the

reason why one network administrator

might have several under administrators

to help them they not only log when

someone comes in or out they can see

when someone visits a specific website

when they're sending or where they're

sending data what the type of data is we

might also have for instance an exchange

server which would be for email in which

case we need someone to manage that as

well for instance what if someone sends

a 50 megabyte or 50 gigabyte file by

email or they try to that's going to log

up the entire network

so one of the first duties of an

administrator is documentation there's a

couple reasons why this is so important

when it comes to managing and running a

network it's going to be the focus of

its own module but it's good to get a

basic understanding right now because

the process of documenting everything

can be really time consuming but it's

also really worth it can save you a lot

of time trouble and money when things

are well documented and no one has to go

searching for them especially if the

administrator is out of town or if we

switch administrators we want to make

sure that the network can still live on

its own now there are no shortage of

things to handle for the administrator

and documentation is OB usually the

thing that's going to get pushed aside

and forgotten about but there are some

really key items that we can look over

that are helpful to be dealt with first

of all properly documenting information

is useful when training new admins it's

not uncommon for the old administrator

to leave and then have to train a new

one is their replacement however the new

admin doesn't have time to learn the

topography the cable connections

everything about the network from

scratch so this is where proper

documentation is really helpful it can

save the new administrator a lot of time

and effort especially if even if you're

not leaving if you bring on someone to

assist you allowing them to look at

documentation is going to save the super

administrator time from having to teach

the new administrator

it's also going to help us when we

troubleshoot problems on the network it

can save time and money because we can

eliminate the time it takes to test

every possible problem because we can

now isolate where the potential problems

are for instance if I have an overview

of where things are set on the network

and I know one side of the Network's not

working then I can automatically sort of

go to that side of the network and not

have to worry about the other side

finally it's also really important when

I'm bringing in outside workers to make

changes to the network they need

accurate and up-to-date information

about the network its layout and if

they don't have an idea of how my

network looks and I just start to tell

them to fix things they're going to have

major issues and one of the things

that's really big these days is having a

contractor come in because we're sort of

going to Outsource a lot of our network

administrator duties or sometimes the

administrator is not a specialist in

something Sprints in security and so

they need to bring in contractors to

implement a better security plan

now monitoring is also an extremely

important job for the administrator it's

necessary to monitor a network for a lot

of reasons and again we're going to talk

talk about this in its own module but

it's good to understand it a little bit

right now so when you monitor a network

the administrator can almost always find

faults in the system and find out where

they are there are tools that help the

administrator check all the devices to

find out where the faults are and how

they can be fixed and I think we've

looked at some of those and we might

look at it a couple more but some of the

tools the Ping trace route Etc looking

at routing tables looking at broadcast

all this stuff and also performance

detection is very important when we're

involved with network monitoring when an

administrator monitors performance

they're able to find some very useful

data they can discover Network usage

data how each user has been using the

network and make sure that the bandwidth

is load balanced properly a term that we

have seen a bit and we're probably going

to see a little more

and also we can make sure that nothing

if there's not too much traffic on the

system obviously too much traffic slows

things down and makes everyone miserable

finally security monitoring is really

essential because uh one thing we don't

want is someone outside of our Network

getting access to all the stuff we set

up it's really going to make your bosses

upset too and we're not just talking

about hackers we're talking about

viruses attackers any of this stuff so

when we're monitoring security an

administrator can find holes in the

system and then take preventative

actions in order to stop the attacks

before they happen one thing that's

going to help with this are two devices

called an IPS or an IDs an intrusion

detection system

and then an intrusion

prevention system

these are actually two different things

as you can see from the name intrusion

detection just detects when something

happens intrusion prevention is actually

going to stop it in its tracks so that

was just a broad overview of defining

what an administrator does the person

who overview who has a complete overview

of the network

and then we looked at a couple of the

reasons why their admin duties of the

documentation monitoring are so

important documentation for training new

people

tech support

uh bringing in outside resources

and also monitoring not just for uh

security reasons

but also for performance

because obviously if we have a slow

Network it's going to result in everyone

being unhappy and your boss is not being

able to be able to accomplish the work

they need not to mention if we talk

about one extra minute in work time that

can actually cost us quite a bit of

money in the real world so having giving

us a broad overview of this we're going

to talk more about uh optimizing a

network Performance Based on the

monitoring that we do

[Music]

thank you

Network management optimizing Network

performance

we're going to be covering a lot in this

module it's all about the optimization

of a network and its performance and

there's a lot that we have to do as

administrators when it comes to that

we're going to specifically focus on

strategies to optimize network speed and

efficiency

so first we're going to give an overview

of what network optimization is and then

we're going to define something called

quality of service qos which I want to

point out right now you're going to see

anytime we talk about voice over IP this

is the name implies what we're doing is

trying to make sure the service provided

on our network has a high degree of

quality and when it comes to voice over

IP we need to make sure the quality is

pretty high

there are two ways to do this one is

called latency sensitive and the other

is latency insensitive and we'll Define

that a bit more

we're also going to talk about something

called traffic shaping and methods in

which we do this and finally caching

engines which help speed up Network

performance as well

so

bandwidth is essentially the amount of

data that can be transferred and

utilized at any given time this amount

is usually expressed in bits per second

so if you remember we see for instance

mega bits per second with the small B

and I want to point out again that this

is not megabytes per second as you

recall there are eight bits

in every bite

so we would really need eight

mega bits per second to equal one

megabyte per second just something to

keep in mind as you purchase uh perhaps

a broadband connection now how the

bandwidth flows is dependent on how many

people are using it at once and for what

purpose so everything in today's world

is expected to be fast and we can settle

for no less than the fastest it will

become really impatient with network

speeds very easily and unfortunately

they fluctuate fairly easily too

especially in a corporate environment

where there are a lot of people using

and taking up the same bandwidth just

imagine how frustrated workers are going

to become with uh when they can access

something really fast one second and

very slow the next you can imagine this

at home as well

so the purpose of network optimization

is really to help control the traffic on

a network the large group of people are

trying to enter a building through one

door the flow is going to be a lot

slower than if there are multiple doors

and the same principle applies to

networks if the network is laid out and

run in an optimal way there is less

chance of blockage so in addition to

network traffic optimization Works to

utilize bandwidth in the best possible

way so that everyone can use it at the

same time this would be also called

throughput

so whereas bandwidth

is our ideal or possible

throughput

is the actual

in other words what actually makes it

through the bandwidth

so here's a representation of what

bandwidth might look like imagine the

bandwidth capabilities are like tubes

and the bigger the tube the more that is

free to throw flow through it so here

you can see there's much more ability to

flow through the tube on the right

because it's a lot bigger than the tube

on the left that being said only because

our bandwidth is for instance 90

megabits per second or one gigabit per

second doesn't mean that the throughput

is actually going to be that I'm sure

that you have at home uh bandwidth or

broadband internet

and it probably says it has up to

perhaps maybe 15 megabits per second if

you're on cable but sometimes you're not

always getting 15 megabits per second

you might be getting five or eight

megabits per second and you can test

this using different sort of online

speed test uh utilities but only because

we have a certain amount of bandwidth

doesn't mean our throughput is going to

equal that which is an important

distinction

to make

what we want to do is get the bandwidth

and throughput to equal as close as

possible to one another

so there are strategies used to increase

the use and optimization of bandwidth on

a network

these strategies are called quality of

service or short-term qos

now they have a lot to do with

information and helping it optimize the

network so qos allows administrators to

predict the bandwidth use on their

Network monitor the use of it and then

control it this is done to make sure

that there is available bandwidth for

any one application that requires it the

applications that need this bandwidth

are generally split into two different

categories

latency sensitive and

latency insensitive latency sensitive

applications are appropriately named

these are applications that are affected

by latency or a delay caused by a device

so latency is sort of the slowness with

which bandwidth occurs or not living up

to its full potential

so an application that needs bandwidth

because of its Effectiveness is impacted

by lag time for example applications

that use VoIP fall into this category or

voice over IP they're latency sensitive

because lag time could disrupt a video

or a phone call latency insensitive

applications still require bandwidth but

for a very different reason these don't

have video or voice transfer so the

bandwidth is just as important to them

but the latency doesn't really matter

these applications are those that are

used to transfer large amount of data

like during backup or FTP

just to cover this one more time and

perhaps say it in a different way

latency sensitive would be meaning that

if something for some reason I have a

huge uh amount of traffic then I'm going

to start seeing a degradation in service

when it comes to my latency sensitive

applications such as VoIP for instance I

need to make sure that no matter when

I'm talking over my VoIP phone it's

still reaching the end person in the

same degree of quality it can't be

dropping a lot of packets because if it

is then they're not going to be able to

hear my voice very clearly with latency

insensitive the traffic can modulate

quite a degree because as long as the

files get from one end to the other if

at one point it's transferring at 90

megabits per second and the next the

transmit one gigabit per second it's

still going to get over to the other

place but it doesn't really matter if I

don't receive the packets in a sort of

steady stream so in this case the

latency doesn't really matter as much as

the fact that it simply gets from one

place to the other it within a certain

degree of time

so a very important qos strategy to help

exist to help control the flow of data

through a network is called traffic

shaping

its main purpose is to reduce latency

which it does by controlling the amount

of data passing through a network data

traffic is sort of split into different

categories and put put in something

called a queue a queue by the way would

be something like a line basically I'm

going to put certain types of

information into one queue and certain

it to another and those cues are going

to be given priority

so my voice application is going to have

the highest priority whereas maybe my

FTP will have a bit of a lower priority

now there are quite a few different ways

to use traffic shaping and each method

has its own benefit and needs to be

chosen based on the circumstances of the

situation now here are a couple of the

common methods actually three

first is shaping by application

this is a strategy that involves the

administrator allowing only a certain

amount of bandwidth to be used by a

certain application for instance an

admin only allows a VoIP application to

use for instance six megabits per second

and it can't use any more than that so

in some ways we set a limit

to the bandwidth that's going to be used

by a certain protocol or a certain

application

the next which is called shaping Network

traffic per user allows the

administrator to limit the bandwidth

that any individual user can use now

shaving by application is something that

we're going to be seeing a lot now on

airplanes and trains we don't want to

let for instance people use Netflix and

YouTube on the plane because there are

other people who need to be using email

and so we're just going to say if you

want to do bandwidth for video we're not

going to allow that as much as bandwidth

for say

email or for text messaging for instance

but when I'm talking about Network

traffic per user I'm allowing specific

users to have a certain amount of

bandwidth so some users might use more

bandwidth than others and sometimes it

isn't all for work reasons for instance

let's say that Anthony from sales is

constantly streaming video or audio to

his computer this is using a lot of

bandwidth so now the discipline part of

this may not be up to the administrator

but he or she can certainly limit the

amount of bandwidth Anthony is allowed

to use so if each and visual for

instance Anthony is limited to 256

kilobits per second it's not going to

access what he can access just how fast

he's able to access it so whereas this

is really doing it shipping by

application based on the type of

information shaping the network traffic

per user

is on an individual basis and this way I

can give each user

let's say Anthony Maria

Amy each a certain degree

of bandwidth

so that no person can use one more than

the other of course a downside with this

is if Amy's only using let's say 10

kilobits per second to send emails and

Maria is on the video team and is trying

to use all of her 256 she might be able

to use some of Amy's but because of the

way we've shaped this per user Marie

doesn't get any more and sometimes what

we'll do is give people in certain roles

the company a little more traffic or

bandwidth allowability than some of the

others for instance accounting probably

doesn't need as much as our Graphics

team

finally we have something called

priority shaping which is the way to

allow more bandwidth to to those who

require it most sort of what I'm

referring to

here for example in a school system the

teachers need more bandwidth in the

students so the network admin shapes the

traffic again we have that great term

priority shaping so that it's dedicated

more to the teachers but the students

can still use it at a slower speed so

when the teachers don't need the

bandwidth the students are able to

access it at faster speeds so we're

really taking this sort of concept

and allowing it to be a little more

flexible

now another technique used is something

called a caching engine

caching is essentially temporary storage

although the storing of what is changing

every single time

in the case of caching engines the

temporarily storage of data is actually

web data that can be used in the future

so this is happening through something

called a proxy server

basically what's happening is without

going too far in depth into it is that a

proxy server caches web data for future

uses by others so if I have let's say

three users

and the first user and I have a proxy

server in between them before it goes

out to the internet

and the first user requests

CNN

the proxy server which holds a cache

or sort of copies of everything

we'll first say hey I have the latest

CNN or I don't have the latest CNN it'll

then go out to the internet

get the latest CNN

and hold that

in its proxy now when the second user

five seconds later says Hey I want the

latest CNN the proxy server does not

have to go out to the internet we can

basically cut out this entire process

and instead it just Returns what it is

already cached it can do this with as

many uses as possible and what we'll

generally say is that every minute or

every few seconds it's going to update

the proxy server is going to update its

information that way we can make sure

that it's still the most up-to-date

information which is one of the

downsides of using proxy servers and

caching is that sometimes

um it's not going to have the most

up-to-date information but it certainly

speeds things up by cutting out this

whole process of having to go out to the

Internet by keeping it locally

now this all saves bandwidth because

obviously I'm not having to go out to

the internet and therefore I can reserve

that bandwidth speed that would have

been used for video or something else

that's new uh instead of having to use

it for information that I'm gathering

over and over and over again you can

imagine in a corporation of thousands or

hundreds of thousands of people this is

really going to save us a lot of time

all right so just to recap we talked

about Network optimization there were a

couple terms we mentioned first was

bandwidth bandwidth is the highest

possible speed that we have on our data

connection we also talked about

something called throughput whereas

bandwidth

is the ideal or potential

speed

throughput

is the actual speed how much is actually

traveling and what we want to do is get

these two to equal one another as much

as possible however we also want to make

sure to make good use of our bandwidth

so that everyone can get information

they need when they need it so then we

talked about something called quality of

service quality of service make sure

that we're using our bandwidth in a way

that's going to promote good quality we

talked about two different types of

applications in ways that we use quality

of service first we look at latency

sensitive applications these are the

applications that where there is latency

or

another word for this might be traffic

it's going to reduce the speed on the

network the quality of the service is

going to start degrading so voice over

IP is a great example of this if there's

a lot of things going on in the network

then our voice over IP isn't going to

work as effectively and then I can't

count on voice over IP as a good

technology so it's important that I make

sure Voiceover IP always has a certain

degree of say bandwidth with latency

insensitive applications we're looking

at stuff where the speed although it

still needs to be fast doesn't matter if

there's latency one second and no

latency the next when we're transferring

high high or large files such as through

FTP then we don't need to make sure that

we're not modulating between 90 kilobits

per second and 90 megabits per second or

one gigabit per second as long as the

data gets to where it needs to go

I don't need to make sure that it's

getting there at the exact time because

for instance with voice over IP if I'm

talking it needs to be able to reach the

person sort of the degree that I'm

talking but with FTP it doesn't really

matter if it's getting there in the same

instant

we also talked about traffic shaping

which is one of the ways that we use

quality of service and we shape

the bandwidth so that it is used in an

appropriate way we talked about three

different ways of doing this

the first we talked about was based on

application so for instance I'm going to

give a certain degree of bandwidth to

one application and a certain to another

once all the voice over IP bandwidth is

used that's it once all the FTP

bandwidth is used I don't have any more

and so I'm only giving if I have a large

bandwidth let's say this box represents

bandwidth

then I'm going to sort of divide this

into layers

so FTP gets some

HTTP gets some voice over IP gets some

Etc

we also talked about user specific

which means that instead of dividing

things up

based on the application I'm going to

divide it up based on the individual

so Maria gets a certain amount

Anthony gets a certain amount

and Amy gets a certain amount

finally we looked at priority shaping

which is a really cool term

and what this means is I can give

certain priority to certain individuals

or groups so for instance we use the

teachers versus students comparison

teachers we want to have a lot more than

the students so students get a very

small amount whereas teachers get a very

large amount same with on a corporate

Network perhaps I want a management or

my Graphics team to have a lot more than

say my accounting team or lower

management or the secretaries finally we

talked about caching engines and we use

the word proxy server this is going to

save us time because whenever I go out

to get information from a website I

don't have to go get the information

fresh every time instead I'm going to

use the proxy server to hold a copy or a

cached version of my website and that

way I don't have to go out to the

internet every time and I can reserve

that bandwidth for other things I might

need to use

[Music]

thank you

okay welcome to module 11 lesson 3

Network documentation a little bit um of

a harder on this it's just a bit

easier Terry can wishy-washy

um although it's obviously important

but just to discuss and what is it I'm

sure you could actually work out well

one network documentation is why do we

why do we have it importance of it

parts of it

and many General assets and our Network

diagrams

RFID which we go into

tracking our IP address utilization

which is quite a handy thing to have

actually information about vendors and

contractors and all of our policies and

procedures

so the whole principle behind Network

documentation is professionalism really

and business continuity and it's um an

emerging field

and in the world of I.T non-technical

but looking at audit trails and um yeah

in the context of documentation really

and all of our procedures

so critical role and especially when

there's a problem because people start

scrambling looking for what to do in

terms of procedures and policies who

does what

um where to find them how to contact

them and

um where the technology is and how to

fix here there's a whole bunch of

procedures and documents that have to

all be easily accessible and come

together and bear in mind that um the

network could be down there could be an

outage so if it's contained on a service

somewhere then that might not be um

ideal if it's only kept on the server

anyway

so um you can't remember everything

especially if it's a large Network or

even worse if it's a small company and

somebody leaves the business and you

take over from them if there's no

documentation then it causes a lot of

Heartache

um and yeah if you're the one to have

joined it's um it's pretty difficult

because you've got to learn the network

from scratch

and it's not possible to go and search a

network organization administrators

who've quit

don't believe they have their phones

taken off them or they're just going a

long vacation so you don't got to find

them

so it gives Network administrators

information about the network appearance

logical versus physical

baselines how it's performing I should

perform to see if there's anything

um out of the ordinary

um where to begin troubleshooting

so the main purpose is to keep the

network running smoothly so we've got

that five nines

99.99 uptime ideally

it's important to maintain the

documentation and keep it while

maintaining means keep it up to date

because out of date documentation

actually causes more problems than it

fixes because all of a sudden you're

looking at the wrong devices or the

wrong ports or the wrong IP addresses

and I've been there

um so yeah that's what I've said

essential Parts include Network diagrams

Asset Management IP address utilization

you could have more or less depending on

your organization and the size of it you

did information about the vendors and

contractors procedures and policies who

should be doing what and when and also

logical and

um physical this is a

a topology diagram of all the hardware

and the connections we haven't named the

ports on this particular diagram it's

copyright as Scott McDonald

uh just to give you an idea this looks

like it was done in Vizio which is a

Cisco Network creation

um diagramming tool there's others out

there it's a free to troll or some are

free to use

and it shows you all your different

devices

The Logical provides the logical view of

how the network sees itself not how we

will physically see the network in the

server room

uh indicates how the traffic flows

between devices in the network so you'll

see all of your vlans routing

redistribution all these kind of things

bgp if you have it

a logical net Network diagrams include

domain names IP addresses and the tasks

performed by each different device

logically includes how devices

communicate with each other which

direction the traffic flows

and how all these devices work together

the physical network shows the actual

physical connection so you can look at

the diagram of a certain router and you

can see which ports

are on the router how many and what it's

actually physically connected to and a

lot of companies use the concept of

remote hands so you can use these

diagrams to tell the remote hands where

to find the device and which cable to

plug unplug Etc

physical network is the physical layout

that I've mentioned so here's a typical

diagram above is the physical topology

and below is logical topology

so you might not necessarily see all of

the hardware devices you're going to see

things like vlans connections going out

to isps

and hot standby routing protocol all

this kind of thing

uh you won't generally see end devices

on the topology diagram so this is a

very small Network or unless one of the

end devices happens to be your network

management server or something like that

so your documentation should include

notes about Asset Management a whole

bunch of things name model number

manufacturer data purchase a version of

software running does it need updating

is there problems of that particular

release of software updates location

warranty and who has it who's

responsible for it if you're sitting

under some under somebody's desk and

nobody knows and it doesn't serve any

purpose

so you should keep track of all your

assets and eventually there's normally a

disposal

a procedure as well where the devices

are wiped and fragmented defragmented

whatever and whatever type of um

scrubbing is done on their drives if

necessary so there's no data that's

important devices are tagged with the

barcodes or RFID is an example of one

here these are normally read by little

um reader gun like you find in

supermarkets if it's been tagged with a

barcode a barcode scanner will help

retrieve information

and the RFID stands for radio frequency

ID tags that normally have electrically

stored information and the readers are

used to track devices this would

obviously be on a pretty big Network

um

yeah Network documentation should

include your IP address utilization

there's normally one or two people in

charge of allocating addresses or blocks

of addresses

because they're aware of which addresses

should be where which subnets and which

addresses are summarized

and this helps with all of our routing

updates I have seen problems in the in

the past and people should know better

in fact have manually allocated IP

addresses to their devices for whatever

reason and it's caused Network

instability

so Network administrators should keep

track of the number of IP addresses that

have been allocated to the network how

many have been in user it'll normally

Flagger pay alert if you're running

short

if a subnet grows the number of IP

addresses assigned to it you're likely

to have a problem

okay all important to keep uh you know

the utilization as I've said in case we

need to run out or buy some more order

them in advance

you should also have information about

vendors and contractors

that should include vendor names their

services the cost contact information we

normally get our point of contact and

the support hours

or should have um

documentation about all of our policies

and standards well worth looking into a

project management and also ITIL exams

so change management and managing all

your processes and procedures and

problems and on the network

uh provides for example the list of

people who should be contacted certainly

when I worked on a pretty large Network

there was a number of key people so you

have thousands in the organization that

you would contact four or five or six

key people and they would each have a

role of who's going to communicate to

who who's going to tell the boss and do

the does the press or other customers

need to be informed of what's going on

this is to stop uh confusion and also

track back as to who should have been

doing what

policies require compliance and in their

enforce discipline or disciplinary

actions or obviously training if a

person hasn't been given sufficient

training

and normally an acceptable use policy

which new people will sign and everyone

has to sign if there's any changes you

standards of acceptable behavior on the

network

for example creating strong passwords is

a very good one and obviously not

putting it on a Post-It note and

sticking it on your monitor

so we've covered Network documentation

why the importance parts of it diagrams

Asset Management the RFID

and monitoring your IP addresses vendors

and contractors all your internal

policies and procedures

all right so that's all for now thanks

for listening

[Music]

welcome to module 11 lesson 4 Network

troubleshooting model

he'll actually develop your own model as

you get some experience and obviously

depends on your Network whatever your

network or if you're managing just a

small part of the network and if you're

managing a certain OSI layout for

example firewalls or you're a hardware

engineer something like that so it could

vary this is the generic kind of stuff

that CompTIA want you to know and

understand and follow so we'll identify

the problem establish a theory of

probable cause

normally Whoever has just made a change

or plugged or unplugged something has

broken it in my experience

test the theory to determine the cause

establish a plan of action

and then implement the solution sort of

Common Sense stuff really

uh verification documentation

all right so we'll normally gather

information

duplicate the problem if possible you'll

normally duplicate it if it's some sort

of bug and you want to recreate it so

you can send the information to the

vendor to release some sort of update

uh question users users you've got to be

very careful obviously because they can

give you the wrong information or a lot

of users think they know what the

solution is so they'll just give you

answers to questions

that um that they think you they think

will direct you to what they think the

issue is so you'd have to be careful and

question more than one user if you can

identify symptoms determine if anything

has changed normally there has been a

change almost always not every case but

almost always approach multiple problems

individually

so dividing conquer kind of approach

okay question the obvious it's nearly

always something that's pretty obvious

I've seen people waste a lot of time and

energy

troubleshooting less likely issues when

it's almost always the most obvious

thing that's wrong

consider multiple approaches

an example is a top to bottom or bottom

to top using the OSI is it an

application problem and then moving down

or is it a physical problem moving up

and it depends on what the users are

telling you and what the symptoms are

obviously

I mentioned divide and conquer

and this all depends on your network

really but it could be um dividing it

into Hardware all Hardware or and all

layer 7 issues or all cabling issues

something like that it just depends all

the Divine and concrete could be

segments in your network so looking if a

particular vlans affected

or all vlans test the theory once it's

confirmed and determine the next steps

to resolve the problem for example if

it's an email issue then try sending an

email try it from a different users

um device to see if there's more than

one person affected if the theory is not

confirmed you start at the beginning

plan of action obviously and if you can

fix it there and then fix it if it's

requiring a network downtime then you're

going to need to schedule an outage if

you're working on a production Network

again and generally this sort of issue

is decided by this seniority manager or

network manager

potential effects what's going to happen

is it going to cause make the problem

worse is it going to fix it is it going

to cause a different problem somewhere

else

when you implement the solution escalate

is necessary again you normally need

verification of somebody else a senior

manager that this is um

the correct course of action

verifiable system functionality

speak to the user who actually logged

the issue and see if it's resolved for

them and whoever else was experiencing

it if applicable Implement preventative

measures document the outcomes findings

and actions

this is basically useful if somebody

else deals with the same problem I know

when I worked at Cisco attack you could

often put in

error messages and similar things or

look at certain model numbers and you'd

often find somebody else that had the

same problem and you could see how they

fixed it or if they'd established that a

bug had been found and then if that

bug's been fixed in another iOS

all right so pretty Common Sense stuff

hopefully but we've put it into writing

now so you've got uh some sort of method

to follow I'd identify the problem

establish your theory test it plan of

action implement the solution verify

document you need to write that down a

few times you get the correct order in

case it's a drag and drop type question

all right so that's the end thanks for

listening

[Music]

thank you

foreign

network security security fundamentals

in the last lesson we discussed managing

a network and administering a network

this ranged everywhere from

troubleshooting to speed optimization

and in this lesson in the next four

modules we're going to discuss security

now just like with a plus we talked

about networking and Security in network

plus we're going to talk about security

with the understanding that there is a

whole other certification and a whole

other lesson that revolves specifically

around this uh concept so we're just

going to sort of brush over the

important things that we need to know in

a network Plus or network Administration

environment so to start us off we're

going to talk about the basis of network

security and the fundamentals that we're

going to discuss in the next three

modules

so this involves discussing network

security and identifying exactly what it

is when we talk about the basics then

we're going to go over some of the

things that are fundamental to having a

secure network these include keeping the

network up to date

strong passwords

having a secure VPN virtual private

Network

administrating user access in a proper

way

and making sure to remove any inactive

accounts now the reason I focus on these

fundamentals are these are the things

that we'll see on the network plus exam

now the word security means the same

thing just about anywhere you look when

it comes to homes it may refer to Locks

and alarm systems but when it comes to

networks it refers to a lot of different

methods but the concept is still the

same the point of security regardless of

where it is or what it's protecting is

to keep the threats out and the

valuables in think of a bank vault the

door to a bank fault is a few feet thick

it's made of very sturdy metal and this

is because the bank needs to keep the

money invaluable securely inside while

also keeping the potential threats

outside now if someone really wants to

break into a bank and steal the money

they're going to be able to what we want

to do is make it as hard as possible for

them to come in and steal the money

nothing is beyond anyone's purview it's

simply that we want to make it as

difficult as possible for these thieves

hackers or whoever to get in and take it

now the same principle applies to

network security on a network data can

sometimes be more valuable than money in

fact I know a lot of CEO cios CFOs out

there who would much prefer that you

steal some of their money rather than

steal their data especially when it

comes to user data or to private or

privileged information because this

stuff is literally Priceless this is why

it's really important to have a properly

secured Network and make sure that it

stays that way and these are two

different things securing it and then

monitoring it to make sure it remains

secured

now it's very important to make sure

that everything on the network is kept

up to date when programs and patches

have been used for a long time and

they're well known the attackers who've

had an opportunity to find holes with

them begin to make use of those holes

and hack through them

so the longer something is out there and

being used without a new version the

more times attackers have to find

exploits within the program or the patch

this is why as Network admins we need to

make sure that all the programs and

patches are kept up to date programs

that get used often should be updated as

soon as there is a new version or as

soon as a new version proves to not be

buggy now when running a device on

Windows the admin should always check to

see if there's anything available in

Windows Live update or Microsoft update

which we have talked about in a plus

quite a bit now usually this can install

new drivers in patches that have been

updated for performance and security but

other things we need to be aware of are

Adobe products Java which is integrated

into a lot of browsers and the browsers

themselves to make sure that they're all

tight and secure once again we don't

want to update things immediately

because maybe they'll bring down the

system but we need to weigh this against

the fact that if a patch goes out there

to to plug up a security flaw that as

soon as it goes out there the hackers

now know oh look there was a security

flaw and now they can begin to make use

of that security flaw until you update

things so what we're really looking to

do is balance

updating immediately

versus

buggy Updates this is an important thing

to keep in mind

now it's very important that we keep

another aspect of security in mind when

it comes not just to our networks but to

just about anything we're dealing with

on devices and this is our passport our

passwords people tend to think that just

because something is password protected

that means it's safe but this really

isn't true something that's protected by

a password is ultimately safer than

something that's not but a password is

nearly useless unless it's a strong one

think about all the movies in which

someone has to figure out someone's

password looks around the room sees a

picture types in the name of that person

and Bam they're in attackers can use

things called key loggers in order to

log uh what passwords you are entering

on your computer and then send that over

to the hacker they can then take the

letters symbols Etc and being used and

try to piece together what the password

could be depending on the attacker they

might be really successful at stealing

your password simply by just observing

what you type in this is called shoulder

surfing

and it is a big problem when we think

about ATMs people typing at their office

and so on this is a huge problem in

general but it's really problematic if

you use the same password for more than

one thing think about it as soon as they

get one password they have access to

everything especially if they get access

to your email they now have access to

your entire life because they can reset

everything through your email so it's

really important to keep different

passwords for each sort of service that

you access in a general rule you

shouldn't use the same password for more

than one thing this can end up becoming

really confusing if you're dealing with

a lot of different accounts that require

many different passwords so there are

some programs that act as basically

password vaults and they require one

master password to access them and then

you have all of your information stored

inside of those but I think some of

those just have as many problems as

regular passwords all you need to do is

get access to the one program and

suddenly you have access to all of the

password programs so it's important

sometimes for you to create a long

random password word that can contain

special characters like slashes

ampersands Etc these programs can do

that as well but the problem with that

is we're also not going to be able to

memorize that

so and another important aspect of

password Corrections uh protection

rather when it comes to strong passwords

is to use random letters symbols Etc and

long passwords which are always better

than short ones

for instance using the password

password123 is really weak whereas this

one on the right which I can't even

pronounce is really strong now of course

the problem with this is it's difficult

to memorize and if it's difficult to

memorize you're probably going to have

to write it down if you write it down

that gives someone something to steal or

you put it in a password Vault or this

is maybe made up automatically but in

all these cases one password can get

access to all the passwords and so it's

important again we talked in the

previous one about we sort of have to

decide whether we want to update

something immediately or whether we want

to update it you know after a little bit

after it's been tested the same sort of

thing with passwords we don't want

something too weak but we also don't

want something too strong that we can't

remember so the best thing I think is to

think about for instance a pass a code

that for yourself so for instance a

common one with the term password is to

replace

the A's with ATS and the O's with zeros

if you think about creating your own

password we could do this for instance

let's say we wanted to turn this secure

and organized into a password well I

could replace the S with fives

I could replace the ease with threes

I can replace the A's with and

ampersands

and so on and so forth

even an I replace that with a

exclamation point or the number one

and voila I've just created what looks

to the plane eye

as a pretty s complex password that a

computer wouldn't be able to necessarily

break but you remember it because you've

come up with your own code of how you're

going to replace certain symbols and

numbers and it wouldn't hurt to throw in

a couple uppercase letters there as well

now with virtual private networks

there's a lot that can go wrong security

wise because it travels over a public

network in order to collect connect to

your local land and the users remotely

connect an attack can happen from

literally anywhere so in order to help

stop attacks the admin needs to require

remote users to have multiple points of

identification remember in a plus we

talked about having multi-authentication

and remember authentication we have

three different things

something you know

something you have

it's something you are

so if we're going to use multiple forms

of identification

maybe one thing we want to do is have a

standard username and password and also

a pin or security question they would

have to answer these both fall under

something you know we could also give

them a fob key that has a rotating

password on it this would be something

they have it makes it more difficult if

I use multiple forms of this

authentication and that way it's not

just things that are written down or

known it's also things that are have had

or even better things that you are for

instance a retinal scan fingerprint

voice recognition

Etc the point is the more of these you

have the easier it is for you to keep

your stuff secure however it's also more

difficult to log in and it's going to

take more time so again we're dealing

with time

and ease

versus security and we have to find the

right balance

because we don't want people to get so

turned off by all the heightened

security that then they can't use our

product

it also might be necessary to have a

firewall between the VPN and the

physical Network the firewall acts as a

sort of last line of defense and if

somehow an attacker manages to get

through the points of identification the

firewall might be able to stop them from

connecting to the network based on where

they are the information they're trying

to transmit if they're using an unknown

or untrusted

IP address the firewall may be able to

stop them before they connect the local

area network

now it's often the case that users have

to access things that they have no

business accessing for example someone

in the graphic design part of the

company has no need to access the

accounting records of the company and

sometimes however users are given

permissions to access data like this

simply because it's overlooked by the

administrator so this is a huge security

issue and one that's easy to fix and

needs to be looked after with care the

admin should only make sure that users

are given only access to the data they

need to do their job this is what we

call the principle of least

privilege now this change can be made by

password protecting

or it can be made

using group policy

meaning that we have an Accounting Group

and we have a Marketing Group if you're

placed into one of those groups then

you're not going to be able to uh access

anything except for what your group has

access to

now the other thing we want to do is

make sure to clean up inactive accounts

when a worker leaves the company the

first thing the admin needs to do is to

change the password to the user's

account or what we call deactivate the

account it'll be a very bad thing if a

for former employee were to access the

company's files and who knows what they

could do with those especially if they

were fired so once the passwords has

been changed there's no way for them to

access the account but it's not

necessary for the admin to delete the

account right away if the employee was

to come back to the company soon after

and needed to access their old files

they could be given a temporary password

and then monitored to make sure they

could get their old information however

if an account has been inactive for a

while it should be deleted or

discontinued an idle account is really

dangerous thing to have on your network

if an attacker is about to access this

account they could easily slip past

unnoticed on the network until something

actually happens we wouldn't really know

that there's a problem so in order to

prevent this we really want to delete

accounts soon as the users do not need

them anymore this is why generally HR

and IT talk to one another so we can

make sure once we let a person go or

fire someone their account is turned off

almost immediately

all right so these are some of the

fundamentals we talked about the

necessity of network security remember

data can sometimes be more important

than money because it's going to cost a

lot of money in order to recover or make

up for the loss of data we also

identified some of the fundamentals of a

secure network first of all we talked

about keeping things up to date we

talked about keeping up the firmware

drivers

operating systems

patches to Software

Etc and we're always dealing with a

balancing act here are we

doing things immediately

or are we going to wait and possibly uh

be susceptible but we might have buggy

updates

so we sort of want to find a good medium

middle of the road solution there

realizing the longer we wait the more

susceptible we are to attacks we also

want to make sure to have strong

passwords

remember a strong password generally

means it's 15 characters or more the

longer the better

we have numbers

symbols

lowercase letters

uppercase letters

and we want to use them in a varied

random combination

we also want to make sure that we're not

reusing the same passwords

and don't write them down that's always

a problem

now of course again we have a balancing

act here because the more difficult it

is

the

more difficult to password rather than

the more likely someone's going to write

it down and so we need to also make sure

that the passwords are have a certain

degree of ease of use

we also are probably going to want the

passwords to expire every once in a

while

and so on and so forth with a VPN we

need to make sure that there are

multiple forms of Authentication

remember the three things we have when

it comes to authentication something you

have

like a fob something you know like a

password and something you are like a

retinal scan or a biometrics

when it comes to user access we want to

practice the principle of least

privilege meaning you're only going to

be given access to that which you need

access to to do your job accounting does

not need access to marketing and vice

versa finally we want to make sure to

disable

or delete inactive accounts keeping in

mind of course that someone who leaves

the company might need to come back and

therefore we might want to make it easy

for them to have access to their old

stuff

[Music]

network security authentication

authorization and accounting

in the last module we started off this

lesson by discussing the fundamentals of

network security Now a big portion of

network security has to do with AAA or

authentication authorization and

accounting

AAA server on a network is probably one

of the most important things when it

comes to security and it's quite a bit

of work so in this module we're going to

Define and discuss these three A's

Authentication

authorization

and accounting in further detail so we

know not just what they are but how

they're implemented in a very general

way

authentication is the first a it's used

to identify the user and make sure that

the user is legitimate sometimes

attackers and Bots will try to access

the network or secure data by acting

like they're a legitimate user this is

where authentication comes into play

any secure network is going to require

something like a username and password

to log in and any data that's really

important or secure needs to be

protected now there are ways of course

for these attackers to gather the

password and username information but

the smart thing for us to do is to

change passwords for all users on a

network frequently probably every 30 to

90 days again we have to balance that

with how easy it is for someone to come

up with a new password and they're going

to remember the new password they come

up with we need to make sure that the

passwords are documented in some way

although we want to be careful again

because when we write them down and

document them that opens up another way

they can be stolen and we want to make

sure that they're all secure if an

attacker has an outdated password it's

going to do them no good so if we can

put this in another way

authentication verifies identity this is

sort of like you have a ID card or

driver's license that provides your

identity and authenticates you are who

you are one of the reasons we have

pictures on our driver's license or

government issued IDs is so that people

can look at it and guarantee We Are Who

We Are this used to be done with

signatures they would look at two

signatures make sure they were identical

and then we could authenticate the

person was actually us now we've moved

way past this now we can even use things

like fingerprints which more or less

authenticate that we are who we say we

are

so here is another form of

authentication you may have encountered

this one before when you're trying to

access things on the internet this is

called or looks like a captcha and it's

used to stop Bots from accessing secure

data or infiltrating someone's account

or making an account when we don't want

them to so the text in the gray box is

difficult to read for a bot it's

actually a picture and it's very

difficult for robots to read this and

know exactly what to type in

so because of this the captcha is

usually made different fonts distorted

text pictures Etc and it can be slightly

different for a human to read but not so

difficult for them that they can't

actually type it in when you type in the

image into here is text then you can

basically ensure that you are who you

say you are that you are a human rather

than a bot now authorization is the next

security level after authentication it's

the second a so once a user has been

determined authentic we've authenticated

their identity they're going to be

allowed onto the network but they can't

just have free reign and do whatever

they want we want to make sure that they

can only access specific things remember

that concept of least privilege well we

want to make sure that the person who's

on there is only going to access stuff

that they are allowed to access so

you're authorized to access only certain

things now there are users such as the

admin who can generally access a quiet

deal more but we don't want for instance

the administrator to have access to the

partner's private email in a law firm

and we don't want someone who works in

accounting to have access to marketing

so authorization basically provides the

information on what the person or the ID

person who has been authenticated is

authorized to get access to now

authorization procedures can stop users

from accessing certain datas Services

programs Etc and can even stop users

from accessing certain web pages for

instance we sometimes have filters that

make sure our kids don't access very

specific information unless they can

type in a password that would

authenticate that they're an adult so

here's an example of what a denied web

page might look like as you can see the

user is being told that an error 403 has

occurred other words the web page has

been forbidden it requires you to log on

and you have not logged on successfully

so you have not authenticated who you

are and therefore you are not authorized

to have access to specific degree of

information

now users other than the administrator

will most likely not be authorized to

run commands in the command prompt and

we've looked at this with a plus running

things in an administrator mode if the

user does they're probably going to

receive an error that looks like this

this command prompt has been disabled by

your administrator the administrator can

deny every other user on the network the

ability to use the command prompt

because they could do something that

they are not authorized to do so it's up

to the administrator to make sure that

only authorized users can access the

command prompt or do other things on the

computer or on the network for instance

rebooting computers accessing servers

and so on

now the final a we talked about

authorization and authentication is

accounting accounting is not the same as

in bookkeeping it's Accounting in the

sense that everything a user does while

on the network has to be accounted for

and carefully watched this is sometimes

also called auditing

another term that gets back to

accounting in a sort of financial sense

but it means something different the

users on a network uh can often be one

of the biggest of our security concerns

most of the time someone is going to

hack our network from inside rather than

outside and so keeping track of how

users spend their time is one of the

most important aspects of network

security the accounting function of the

AAA servers to do exactly that it

watches all of the users and monitors

their activity as well as all the

resources they're using these resources

could include stuff like bandwidth CPU

usage and a lot more not to mention what

websites they're accessing and so on now

some people say hey wait you're

infringing on my right to use the

internet but if you are at your company

using your company's internet then you

have signed most likely an agreement

saying you're only going to use it for

specific purposes and you've probably

also signed an agreement whether you

know it or not that allows them to

monitor you while you're using the

internet

so here's representation of what the

accounting function of AAA server does

it oversees everything the users are

doing and keeps track of what the

resources are those users are taking up

and how they're spending their time

now this was a short module but it

discussed the AAA and these are three

really important Concepts you need to

know and understand for Network plus

first we looked at authentication

authentication make sure that the

identity has been verified this is just

like in a metaphor your driver's license

which has a picture ID

next we talked about authorization this

is what you are allowed to do

this could be just like you're

authorized if you have your driver's

license and you're 21 and up in the

United States to drink

so

authentication is provided by the

driver's license you are who you say you

are and then authorization says whether

or not you're allowed to drink or even

drive depending on your age and a

variety of other circumstances finally

accounting is basically a log

of what you do

if you get in trouble with the law

that's put on a record that way if

you're pulled over by a policeman let's

say for speeding they can scan your

driver's license and see if you have any

outstanding warrants or if you've been

pulled over in the past in this way

accounting provides a background

information on you and can make sure

that we know what you're doing on the

network what information you're

accessing and also make sure when you're

accessing it and so on let's say that we

have someone rob our store at midnight

and the store is closed well if your

security card was used to get access to

the store then we know that either you

rob the store or someone who stole your

security card robbed your store

[Music]

thank you

network security system security tools

in the last module we talked about the

AAA authentication authorization and

accounting there's three aspects of

security are really important to running

a safe and secure network but there are

also some security tools and programs

that prove really useful when we're

trying to put these into action most

notably we're going to talk in this

module about firewalls and antivirus

software there are a lot of other tools

and pieces of software that we can use

and we'll talk about these in a bit but

these two come up quite a bit on the

network plus exam especially because

they're the two most prevalent that we

see in the field especially from a

consumer's point of view

so in this module we're going to Define

what a firewall is and then identify its

importance and how it works we're also

going to Define anti-virus software and

identify its importance and how it works

so let's start by talking about a

firewall this is something you've

probably heard about you might even have

on your computer or on your home network

a firewall is an essential part of any

secure network especially in today's day

and age and a network would just be at

risk almost constantly without it it's

basically a security system that serves

as a barrier between the local network

and the wide Network or VPN it analyzes

the data packets that are trying to

enter the local network and exit the

local network and determines whether

it's safe to let them in or out or not

in a more General sense a firewall is

set up between local private Network and

a public network like the internet so

internet protection is actually a large

part of what the firewall is used for

now the reason it's called a firewall is

because if you think about it the fire

is going to burn up all the bad stuff

but not the good stuff

as opposed to a brick wall which

wouldn't let anything in so the name

sort of describes what it does people

often establish firewalls as their main

line of defense from internet attacks

and they can be configured to not allow

access to certain websites as well as

not allow downloads from certain

websites or certain ports to be open

we'll use something called a port

scanner to see if there are any open

ports on our Network that are going to

let bad stuff in and what we can do is

actually set the firewall to allow

inbound

and outbound ports

now I know inbound probably makes more

sense than outbound but if you think

about it if somehow I get a virus into

my computer and it starts sending

information out I want to make sure to

keep that information in so that I don't

release any say private information

about my network

now the term firewall as I was just

talking about comes from the physical

firewalls or doors that a lot of

buildings contain these doors are

fireproof and they contain a fire to one

area stop it from spreading elsewhere

which is another way we get that term

they're also meant to block out fires so

this is what a network firewall does but

with threats from outside and inside of

the network

so think about a firewall if we can use

a metaphor as the moat and the stone

walls around a castle everything within

the castle walls is really contained and

localized outside the walls however

there's a public domain the internet

walls in the mode of the castle are the

last line of a large-scale defense

before an attack can infiltrate so this

is exactly what a firewall does it keeps

the public network and the private

Network separate from each other now the

castle much like a firewall does allow

certain things inside this is like the

drawbridge of the castle so when the

walls and the moat keep unwanted things

out but then things are trusted so they

are allowed in through the drawbridge so

firewalls do the same thing with packets

of data they only allow the ones that

they trust to enter the network and we

do this again by allowing or not

allowing certain ports now of course one

of the downsides of a firewall is it can

block good stuff

so for instance if I have Quickbooks on

my computer and it's trying to access

its download server to update the

program I could block the inbound Port

by accident through my firewall and

um then it wouldn't be able to get

updates so this is one of the issues now

firewalls can be either software

or Hardware

you probably without even realizing it

or maybe you do have a software firewall

built into your I OS

so if you have Windows 7 Windows 8

Windows Vista then you actually have a

firewall built in now you could also

have a hardware firewall which if we're

talking about your home network is

generally built into your Soho router

that's right your Soho router contains a

firewall built in and will allow or not

allow certain ports to come in this

awfuls us

two levels

of security

one through the hardware and once it

gets through indoor Network then we have

one on our computer

now like we said before firewalls are

mostly used to block uh attacks from the

outside but it's not the only use see

there are quite a few actually as we

already talked about they keep attacks

out by monitoring everything that tries

to enter if something isn't trustworthy

it's not going to let it through now

though this might be the most recognized

use there are some other important

aspects that we want to talk about for

instance the firewall acts as a barrier

which not only keeps things out but it

makes sure that important things inside

the network don't get out which in

effect keeps the data secure this is

what I was talking about without bound

ports

for example if secure data is being

accessed and taken from someone on the

outside then we can make sure that the

data can't get out through our Network

it's going to be stopped just like

containing the fire within the building

this is really important to businesses

and organizations where data really

equals money or more than money now for

individuals it can help secure important

information like your social security

number credit card information

Etc these aren't things that you want in

the hands of attackers so a firewall can

actually prevent these problems that an

attack might cause

just as a matter of example I'm here in

Windows 7 and let's go ahead and check

out the Windows firewall

now I actually have two options here one

is far with Advanced security and the

plain old Windows firewall

if we go into plan we'll win this far

well you can see the firewall is on and

it's working on this network and if I go

over here I can choose whether or not to

turn the firewall off or on

now if we go to those advanced settings

I referred to earlier

you can see that I have inbound rules

and outbound rules

there are inbound rules that allow and

disallow certain information

for instance this rule which says file

and print sharing Echo request allows

the connection to be made for icmp

packets which is basically for Ping now

I can choose to disable a rule or create

a new rule for instance if I have a

specific program or Port that I know

needs to have access

you remember the ports that we talked

about previously and this is an example

of how you would use that now I also

have outbound rules so for instance

instead of allowing information into the

system I want to talk about information

I want to let out so for instance

Windows Media Player has a number of

rules that are here notice that none of

them are enabled

so if we were to check this one out for

instance it says there's an outbound

rule to allow the sharing service for a

Windows Media Player now I could enable

this and that would allow it to occur

but because it is disabled to this

moment it's actually not going to allow

any of that information out so this is

how very quickly

the firewall works on your software but

it would also work the same way if you

had a hardware device too you can also

have it monitor what's going on so for

instance this is telling me that the

inbound connections aren't matching a

rule so that I could go in and check out

exactly what that is

and it's also telling me I can see all

the active rules and so on that are

going on here now here's an example of

what a fire mole might do as you can see

it's separating the WAN which usually

would be shown by a cloud

which we could call the internet

and the users on the WAN have to be

authenticated and allowed before their

go past this firewall this is useful

because an attack could very possibly

infiltrate the WAN and try to get access

to the local network but if they're not

recognized not given permission by the

firewall they're not going to be able to

enter the land sometimes what we'll also

have is a separate Network that they'll

be allowed into

that's sort of not between the firewall

in some cases even if I erase this we'll

actually have

two firewalls

one which allows a lot of stuff in and

creates sort of a demilitarized zone

which then we can either put a test

server on or a test computer sometimes

we'll call this

a Honeypot will allow a lot of stuff in

through the first firewall

and then when the hackers find stuff

they're going to start attacking this

Honeypot

Honeypot being sort of like bees go into

honey we can then see what they're

looking at what they're trying to get

access to Etc and this gives us a sense

of testing the network security

then once they get into the

demilitarized zone they have to pass

another set of protocols to get in to

our Network and as we mentioned there

might also be firewalls

on each one of these computers if you

can pardon my awful drawing

so we're going to have software

firewalls just like we have Hardware

firewalls in fact this might be a device

or it could be a server

with firewall software built in

now anti-virus software is everywhere

and there are more companies and

softwares that protect against attacks

than you can count some of the ones you

might even know are for instance McAfee

and Norton two big ones there's also AVG

which offers a free one Trend and the

list goes on and on and on now in

general most of the software is pretty

similar and they all do the same types

of things some more expensive than the

others some are more for Enterprises

they have a server set up so you could

monitor your entire network without

having to go to each individual computer

but in effect they all do the same thing

so although a firewall is a really good

resource against attacks there's nothing

it can do once the attack has already

taken place once the system is already

infiltrated so attacks are not always

obvious and sometimes attacks are so

subtle they happen right under our noses

you might not even know you have a virus

until it's already done damage so even

though firewall protects the attack it

can't get rid of the malicious things

that have gotten through this is where

antivirus comes in

this software has many functions one of

the more important ones is that it

offers real-time protection the software

is constantly on the lookout for attacks

and malicious things software that

doesn't look right and firewalls merely

block the attacks whereas antivirus

software will go after an attack before

it goes before it can get through the

firewall now uh this software can also

scan for viruses and remove them once

they're found now sometimes this can be

tricky because just like if I install

the antivirus software

after

the virus has infected my system the

viruses might not be found by the virus

software it's also going to look at

suspicious files and data and place them

into what we call the quarantine

the quarantine just like the name is a

place where we're going to put all those

files that might be infected and that

way we can make sure that we can look

over them as an administrators see if

they're infected and either delete them

or bring them back into the network

finally antivirus software is going to

update itself constantly if you imagine

that viruses and hackers are constantly

doing their work to keep everything up

to date well then you probably have an

understanding that we need to keep the

antivirus software up to date just like

every year we have to create new uh

vaccines for the flu and so on we want

to make sure that the antivirus software

is kept to date this is generally what's

referred to as data files or dat files

and you used to have to download these

off the internet and install them now

this happens usually automatically just

like Windows update but we need to make

sure the setting is correct so that it

allows itself to be updated

automatically

so just to recap we talked about a

firewall remember it works with inbound

and outbound ports it's going to allow

some good things and good things out but

it keeps the ins the bad stuff out and

the good stuff in

we're also going to identify we also

identified rather its importance talking

about how we can have several Hardware

and software firewall Solutions

and again we might have to manually edit

the inbound and outbound ports

to allow for instance a software program

that uses its own port to get out and

get updates one of that software that

might need to go out and get updates

would be our antivirus software which is

what we talked about this is software

that does not it can prevent

an attack but it can sort of take over

from where the firewall stops whereas a

firewall can't stop it once it's already

started an antivirus software program

can go a little more in depth it has to

be kept up to date

and it might not necessarily be able to

remove the virus but it will put the

virus and the files that it has infected

into a quarantine

so that's really what's important about

it and if you've been working on a

computer at all in the past 15 or 20

years you've definitely had to use this

and nowadays actually Windows requires

that you have a virus scan on or it will

actually bother you in the notification

center quite often

so now that we've talked about this

let's end by talking about how we can

protect our data in a very raw sense

called encryption and cryptography

[Music]

network security encryption and

cryptography 101

so to round up our discussion of network

security I want to talk about the way

that we secure data at the source and

this gets to basically encoding the data

that we send so even if it's captured or

sniffed we can't allow the hackers to

figure out what it is that we were

sending in the first place and so this

gets to encryption and cryptography just

like code breaking from World War II or

from our military when they would send

encrypted messages

and because this is a pretty in-depth

topic we're only going to cover this

broadly so first we're going to Define

and discuss cryptography

and then we're going to Define and

discuss encryption including the

difference between plain text and

ciphertext one being the way that text

is sent if we don't add any encryption

and the other one if we do add

encryption and then public and private

Keys sort of like decoder rings for how

we can read the ciphertext the public

and private part comes about in the way

that we have the sender and the receiver

decode and encrypt certain messages

finally we'll identify examples of both

and how they work now this entire

subject gets a lot more in depth if you

go into Security Plus and the CompTIA

Security Plus certification so here

we're just covering this in a sort of

very broad sense there are people whose

entire jobs it is to Simply deal with

this aspect of networking

so in a very general sense cryptography

is the practice of securing information

using codes in order to keep adversaries

or hackers or outside folks from

understanding it now the word adversary

generally means an enemy or an opponent

in this case it just means someone who

would want to intercept the information

you're sending it's very likely that

this adversary is your enemy

quote-unquote such as a computer hacker

and although cryptography is not only

used in Computing in fact it's been used

throughout the world even in the United

States and Military Etc it's used quite

a bit here in networking and it's used a

lot in how we package data into packets

so cryptography simply means writing

speaking communicating in code this

practice dates back to the time of

Julius Caesar and quite possibly even

earlier than that Caesar used something

that's referred to as the Caesar Cipher

which we'll look at in just a second a

cipher is a way to encode and decode

data so Caesar used it to send messages

and commands that needed to remain

secret we were also used it in the

United States during World War II uh the

Japanese used there have been a whole

bunch of movies about this cryptography

and ciphers play a large role in

communication especially when we don't

want our enemies to know what we're

talking about

this was true all over the world people

began speaking over the radio writing in

codes in order to keep information

secure so a language like the English

language might be a form of cryptography

to someone who speaks Spanish if they

don't understand the language However

the fact that there is a dictionary out

there that translates everything for

them means that the code is pretty easy

to break so what we're really talking

about and what the Caesar code did for

instance is replace

um every a went down three numbers and

replace it with a d so whenever you saw

for instance uh the word

Apple

we would add

plus 3 would be our code and so if we

went down three if we wrote this out

from a is b c d

from p is QRS

from L is M N O and from E is fgh so if

we were to write Apple in the Caesar

code this is what it would look like and

that's because if we went back three for

each of these we would get the word

Apple now there was only one code that

remained unbreakable in World War II and

it was used uh by the US so the Japanese

could not intercept messages that were

being sent the US actually Enlisted the

help this is a really interesting fact

of Navajo Native Americans in order to

help them transmit messages and these

Navajo code talkers spoke a language

that was so dead and was only spoken by

very few people that every U.S major

base had a Navajo code Docker with them

and they would translate messages and

send them over to each other it was

never cracked by the Japanese there was

even a movie about this so this is how

cryptography worked right if we have a

language that someone doesn't understand

then that is a form of cryptography fee

there's no dictionary in this case of

the Caesar code all right this is what

he did

and uh if we want to look a little bit

closer at how that worked we can see the

Caesar Cipher basically every letter in

this case we're going back three

uh it was in the original text and then

you would go back and so a became x b

became Y and so on what we did earlier

was actually go forward three so

whatever it was we could figure out what

the code would be simply by minusing or

adding three so for instance if we were

to write ABC right now in the Caesar

code with a minus three it would turn

into x y z this is a really simple code

which is why it's not used anymore now

we have a much more

intense codes that are used now compared

to cryptography encryption is the

practice of putting important and

confidential information into a code

that can't be accessed by unauthorized

users encryption is basically the use of

cryptography as you can see by the word

here

so encryption is usually used for

information that we want to keep as a

secret or that's someone we we want to

make sure is not going to get out to

other people now a lot of times we're

going to use encryption with not just

regulate and we're going to add higher

end encryption to stuff like credit card

numbers Social Security numbers Bank

information

Etc

so encryption is really just a part of

cryptography cryptography is broader

encryption happens with the data that is

being sent through a network so like

cryptography and encryption encrypted

message is coded and appears to be

complete nonsense to someone who doesn't

know what the code is now the data is

run through an algorithm in order to

place encryption on it then on the other

side the reverse of the algorithm is

used to decrypt the data and an

algorithm is a mathematical equation

that can be used for several different

things for instance in the Caesar code

the mathematical equation if we had X as

the uh plain text

and Y as the cipher text or the text

that had a code added to it we could say

that if we took the code it would equal

y plus 3. so if we had x y z and that

was our code

and we added 3 to that

then we would end up with a b c and so

that's how that all sort of works now

encryption in an algorithms are a lot

more intense than the one I just sort of

laid out and they're used not only to

code data but also to decrypt it or

unencode it in a way that can't be read

by our adversaries or people outside of

of ourselves

so through the encryption process we

come across around two different types

of text that I just pointed out first

there's plain text this is the

unencrypted data at this point anyone

can read what it says because there's no

code on it then there's ciphertext which

is the encrypted data the data that can

only be decrypted using a special key or

using that special algorithm

so in the world of encryption there are

normally two different types of keys or

algorithms in other words that come into

play first there are what are called

public Keys these are generally used in

some cases

to encrypt the data these keys are known

by both parties that's why they're

public they're put out on the web or

they're sent out by email or something

so everyone has it and these keys are

known by both parties so that in a data

transfer they can be used to encrypt the

data now in most cases the and receiving

the data receives the public key also so

if I'm sending you uh an encrypted sort

of message I'm going to send you the

public key along with my data now the

way that encryption and decryption will

work is the same way these public Keys

run plain text through the encryption

algorithm and they Place coding on it

now private keys on the other hand are

usually only used to decrypt the data so

I will send you my public key you will

encrypt a message send it to me and I

can only decrypt that using a private

key which only I have and so this is

basically how the whole system works now

there are different types of uh

encryption systems somewhere both sides

have to have public keys somewhere we

have a private key again I'm not going

to get too in depth with that right now

because this really gets into more of

security and Security Plus but the

important thing to realize is that the

public key

goes to both parties whereas the private

key which is only used usually to

decrypt the data is only held on to one

person so I could anyone can encrypt the

message but only someone with the

private key is going to be able to

decrypt the message

so if we take a look at how this works

um company a needs to send data to

Company B but it's really important

information that needs to be secure and

encrypted so Company B sends the public

key to company a

company be created this public key so

that the encryption and decryption would

work with each other now company a uses

this key to encrypt the data then sends

it to Company B and Company B uses the

private key that only they have

in order to decrypt the data now you can

only encrypt in this case with the

public key and you need the private key

in order to decrypt that's how this

works but the way that company a got it

is because Company B sent the public key

over to them

all right so just to recap we began by

defining And discussing cryptography

cryptography again is basically having a

code of some sort uh we use codes in all

sorts of ways we talked about the Navajo

Indians using codes during World War II

and we also talked about the Caesar

Cipher which basically just means adding

a certain number

two uh letters so for instance if I have

plus 2 as my Caesar Cipher and I want to

write the letter A instead I'm going to

write the letter c because it goes a b c

right there are two added so then if I

sent this C to someone they know oh I

can subtract two from it and that's my

Caesar Cipher now we also defined

encryption and encryption is actually

the process of doing all this we have

the code we have the cryptography and

then what we want to do is actually

encrypt the data using it now we talked

about two different things plain text

and ciphertext plain text is the data

before we apply the code to it

ciphertext is after we've applied it to

it so plain text anyone can read

ciphertext only those people with the

code breaker can read or the keys we

also talked about that in a public and

private key public keys are sent to

everyone so everyone has access to them

private keys are only held by one party

they are private now generally speaking

public keys are used to encrypt

whereas private keys are used to decrypt

so anyone can make uh a message that is

in ciphertext but only the people with

the private keys can actually decipher

it

and then we talked about some like

examples of using this for instance not

only the Caesar and the Navajo but we

also talked about wanting to use it for

Social Security numbers passwords are a

big one

and of course today's market with all

the finances going on bank and credit

card information

[Music]

network security IDs IPS implementation

in the previous lesson we talked about

different aspects of network security

now because this topic is so

encompassing we're going to continue on

with this network security in this

lesson where we're going to focus

specifically on two types of security

one is IP security which we'll talk

about in the next module and in this

module we're going to talk about

intrusion detection prevention systems

otherwise known as IDs and IPS these are

pretty important and come up a bit on

the network plus exam which is why I

want to commit an entire module to them

so we're going to begin by talking about

an IDs or intrusion

detection system

notice the D there and we're going to

talk about the two different types of

IDs that exist one is behavior based and

one is signature based we'll discuss

what this means in a bit we're also

going to Define and discuss ips's the

difference between an IPS and an IDs is

where an IDs is an intrusion detection

system and IPS is an intrusion

prevention system notice the difference

between the D and the P one simply

notifies you the other will actually

prevent we're then going to discuss the

importance of having an IDs IPS and in

some cases we will have devices that do

both

and we're then going to discuss very

briefly implementation now of course

just like anything we're going to look

at this from a mile high view so this

isn't the in-depth the detailed version

this is the broad overview now an

intrusion detection system is software

or network device that's used to detect

again remember that word d detect

attacks or intrusions that are made on

the network the attacks that it detects

are then reported to either the

administrator or to a threat log sort of

like the Event Viewer if it logs the

information first it then alerts the

administrator so the administrator can

look into the issue now while IDs are up

to date and make alerts as soon as an

attack occurs they are still referred to

as passive the reason they are called a

passive security system is because they

don't do anything to actually prevent

the intrusion from stopping all they do

is they passively notice that it's

occurring this is because again they

merely a detect the attack they don't do

anything to prevent or combat it now

there are a few different types of

intrusion detection systems but I want

to focus specifically on two different

types the first is called a

behavior-based system this makes alerts

and reports of attacks based on the

behavior that they deem to be suspicious

or out of the ordinary these unusual

behaviors can include large amounts of

traffic policies being violated

um and even people attempting to access

things that they're not supposed to

now a signature-based system detects the

Rest by reading their attack signatures

just like a virus scan program has a

signature remember those data files we

talked about that tells it what to look

for in a virus intrusion or attack

systems have a signature and a signature

file that they can look at that lines up

with the signature of an attack or an

intrusion

so signature based systems scan the

signatures of known attacks and when it

detects one of these signatures

attacking its system it makes an alert

to the administrator or reports it to a

log so again the signature is based on

more or less a history whereas behavior

is based on what we see

they're looking at two different types

of attacks and there are the pluses and

benefits pluses and minuses rather of

both but you can see Behavior again is

looking at a more all-encompassing

General sort of view where a signature

based is looking at previous histories

of attacks and aligning the upcoming or

current attack with that

so here's how an IDs Works an attacker

shown on the left sends an attack

through the internet in order to access

the network of the local app

area network the attacks go through the

internet towards the network now in

between the internet and the firewall is

this IDs and what it does is it detects

the attacks being made and sends an

alert to the administrator

though it doesn't do anything to block

the attack this is okay because the

firewall is still set up to handle the

attack so the attacker comes in isn't

able to access the information

but the administrator is still alerted

that there is an issue going on and in

case the attacker begins to double their

efforts the administrator can sort of

get on it and make sure that nothing is

going to get through now similar to the

intrusion detection system and intrusion

prevention system also detects attacks

that are targeting the network however

intrusion prevention systems not only

detect the attack they also prevent it

from happening and causing more issues

on the network these are considered more

reactive

or proactive

software or Hardware because ips's do a

lot more than ids's do they're reactive

in the sense that if an attack is

attempted they're going to block it from

entering the network just like uh a

breaker box is going to

sort of kill the circuit by breaking by

switching the breaker before the

electricity can do any damage to the

wall a ips's might even kill the

connection out to the internet to stop

anything from happening they're also

proactive because certain ips's are

going to seek out attacks and stop them

before they even make an attempt on the

network uh for instance scanning for

ports in this way an intrusion

prevention system is more expensive than

an IDs but this is because it does a lot

more to provide safety for the network

rather than leaving the job in the hands

of administrator who perhaps isn't even

on site at three in the morning the IPS

is going to handle the attack and

prevent the attacker from connecting to

the network and IDs only alerts the

administrator and does nothing about it

for this reason ips's are more expensive

neither system is exactly cheap and

ips's can sell for maybe even fifty

thousand dollars depending on how

versatile it is so here's what an

intrusion prevention system looks like

as you can see it's pretty similar to

the IDS but with one major difference

it's that

the intrusion prevention system is

actually going to stop the attack from

taking place it still sends an alert out

to the administrator so the

administrator can take care of this but

it actually stops the attack in its

place and makes sure that nothing is

going to occur whereas the IDS is going

to rely mostly on the firewall to add

Prevention Services again this is a lot

more expensive but if my network has a

lot of stuff going on in it I probably

want to spend the money in order to

provide more security for my network

now there are a few reasons why

implementing an IDs or IPS is beneficial

first they're going to help provide

additional security to a network the

more security we have the more one of

the important words we see a lot in

computers the more redundancy we have

the better adding layers of security and

IPS and a firewall for instance is like

wearing multiple layers of clothing in

the cold the more layers the more

protected you are now firewalls and

Antivirus systems are great but they are

flawed in that they're not able to

handle every type of threat ids's and

ips's can detect and take care of

threats that might not otherwise be

found by the firewall or by the virus

scan program so there's really not a

single system or program that can

protect against all attacks but the

protection features of multiple

different types of systems can actually

add up to very thick layers of

protection for an attack finally the IDS

IPS keeps a record of all the attacks

they detect this comes in handy because

it lets the administrator see where on

the network they're being targeted most

and then allows the administrator to

make changes add protection of the

places that are attacked most often and

most importantly create new policies

that are going to prevent security

breaches in the future now while I'm not

going to get into the technical aspects

of implementing these systems as I said

I want to talk about what we need to

consider while we're considering putting

in an IPS or IDs first we need to figure

out the ideal placement of the IDS IPS

on the network this means figure figure

out where the sensors are that are going

to provide the most coverage an IDs IPS

needs to be set up where choke points

are available a choke point is a

strategy that involves narrowing down

the physical space that an attacker is

able to utilize and The Logical space as

well this way the defenses must easier

so we're really limiting the area

of our vulnerability much like

Achilles heel using choke points is

actually something that's been in

militaries throughout history notable is

like the Spartan Army of 300 men which

it used against the Persians when they

were greatly outnumbered by forcing all

of the attackers into a smaller path

so if we had a mountain right

and we make sure that everyone's coming

up through this path then we can really

attack them a lot easier from Atop The

Mountain rather than having them come

all around the mountain

next the administrator needs to

fine-tune the alerts the IDS and IPS

outputs so that they are more useful if

the alert merely says an attack is

taking place this doesn't give the

administrator anything to go off of the

alerts really need to be detailed and

tailored to exactly what the

administrator needs to know this is

something that has to be set up and

tested by the administrator once the

alerts have been configured and once

attacks start taking place next the

monitoring of the alerts needs to be

handled what use are the alerts if no

one's seeing them the administrator

can't always be on the network

constantly looking out for the alerts

they're sent so it's their job however

to set up a way for the alerts to be

monitored this might involve hiring an

employee to monitor it constantly

something we used to call beeper Duty

where someone was always on 24-hour call

or configuring a way for the

administrator to get alerts remotely say

a text message

finally procedures need to be put in

place for what's going to happen in the

event of an attack the question what's

our plan of action needs to be asked

just in case an attack goes on so we

know what is going to uh what programs

are we going to deploy what Hardware do

we shut off our connection to the

network Etc if an attack happens it's

really up to the administrator to lead

the defense and the strategy around that

defense

so just to recap we first talked about

an intrusion detection system and

remember that D is really important

which is a passive system because it

simply detects an intrusion as it's

occurring and notifies

an administrator

we also talked about the two different

types of IDs as there are behavior-based

and signature based behavior-based looks

at behaviors

such as high traffic

people accessing things they shouldn't

be or areas being accessed that aren't

normally accessed whereas signature

based looks at historical data in the

form of signature files

and tries to match these up

with known attacks

of course if the attack isn't known then

it's not going to be available in the

signature and so this is where a

behavior would come in play

we also talked about ips's or intrusion

prevention systems

which are proactive because they might

search for vulnerabilities

in the system such as looking for open

ports and reactive

because they actually stop an attack in

its tracks or at least they attempt to

now the importance of IDs and ips's is

added or extra security

just like as we mentioned having

multiple layers if you're going out and

it's cold outside

it's also important because we want to

know how to alter

our security policies over time to make

them more secure

and when we talked about implementation

from a very Broad View some of the

things we talked about is placement

we want them remember in areas called

choke points

meaning we want to limit the amount of

areas that are outside network has

access to to the inside we also talked

about monitoring

and how we get notifications which in

some cases needs to be through text

messaging or email

or anything else finally we needed to

talk about what we do a plan of action

in case we actually have an attack

occurring

[Music]

thank you

network security

ipsec and ipsec policies

having discussed intrusion detection and

prevention systems which are mostly

having to do with keeping attacks and

malicious software off our Network I

want to talk about something called

ipsec or IP security which is a sort of

group of protocols and policies that are

used to keep the data that we have

secure on a network whenever we talk

about security there's something called

CIA the CIA Triad that we need to keep

in mind C stands for

confidentiality meaning only the people

we want to see something actually see it

the I stands for integrity meaning what

we send is what the other party receives

it hasn't been tampered with and finally

we have to balance all of this against

availability it doesn't matter if

something is super secure if no one can

access it so broadening out into this

that's where ipsec comes into play so

we're going to talk about ipsec defining

And discussing what it is and then talk

about two protocols that we focus on

with ipsec ah and ESP

we're also going to discuss three

different services that ipsec uses or

serves one is data verification

protection from data tampering again

getting into that integrity

and private transactions going along

with that confidentiality all of this

supports availability and the reason we

have ipsec is to make sure that in our

security we have available data finally

I want to talk about some of the

policies the ways that we use ipsec

so as I mentioned a good amount of the

security measures that we use on a

network are used to prevent attacks and

shield the network from viruses and

other malicious software but not all

security measures are used for the

preventions of this malicious stuff some

are intended to keep data and

Communications secure within a network

while preventing attacks is certainly a

part of this there are some security

measures that exist to establish secure

and safe communication paths between two

parties this is what IP security or

ipsec protocols do

they're used to provide a secure channel

of communication between two systems or

more systems these systems can be within

a local network within a wide area

network perhaps even over a virtual

private Network now some people might

think that data traveling within a local

network is secure but this is only

sometimes true imagine that someone has

hacked into our Network and we're

sending data across it well now we want

to make sure that the data itself is

secure so while the entire network might

be protected by firewalls antivirus IDs

IPS there might be nothing protecting

the actual connection between the two

users generally the data that gets sent

across the network is not really heavily

protected or didn't used to be so people

tend to think that just because their

network has a shield around it

everything inside it is safe as well but

this isn't the case it's important to

have ipsec protocols in place to secure

the data sent and the connections made

over a network both local and wide area

now there are two main protocols that

are categorized in ipsec they are ah or

authentication header and ESP the

encapsulating security payload let's

talk a little bit more about what these

are

as the name States ah or authentication

header is used to authenticate

connections made over a network it does

this by checking the IP address

of the users that are trying to

communicate and make sure that they're

trusted it also checks the Integrity of

the data packets that are being sent in

other words is this the data that we

actually intended and was it received

properly

the other one encapsulating security

payload or ESP is used for encryption

Services which I think we've talked

about it encrypts data that's being sent

over a network using ah to authenticate

the users ESP will only give the keys to

the users that have been authenticated

so I make sure to authenticate using ah

that this is the user I want to give

something to and then the ESP

does the encryption

for the people who have been

authenticated providing Keys only to the

people who meet the first condition now

if this seems like a broad overview of

these two it is we're not going to see

this a whole lot on the network plus

exam maybe one question but it's not

really worth going into depth because

that's what Security Plus is going to do

and when you talk about Security Plus

you're really going to talk about these

nip Security in more depth then

and there are a few benefits and

services that ipsec protocols provide

the first service is data verification

this service ensures that the data that

is being sent across the network is

coming from a legitimate Source or

legitimate place

they make sure that the end users are

the intended users and to keep an eye on

packets as they travel across the

network

the next service that ipsec is going to

provide is protection from data

tampering again that integrity

service make sure that while data is in

transit nothing changes this could mean

the data somehow becomes corrupted or

that someone literally tampers with it

again while ipsec protocols provide

secure Communications within the network

they don't actually stop an attacker

from entering the network so while there

is a chance of an attacker on the

network they can't tamper with the data

as it travels through because ipsec is

going to make sure that doesn't happen

finally ipsec provides private

transactions over the network this means

that data is unreadable by everyone

except the end users this is where that

authentication comes in and where

confidentiality comes into play

for example if Mike and Steve have to

send some private banking information to

each other the service makes sure that

Mike and Steve were the only people who

can read it this isn't happening at any

level that you can see it's happening

all within the protocols that already

exist when we talked much earlier about

ipv4 versus

IPv6 one of the great benefits of IPv6

is it has all the ipsec stuff built in

so all of this is happening

automatically within our new version of

IPv6 it's not even something we need to

really worry about just something we

need to know is taking place so we can

be a little more sure that our data is

actually being secured

so here is what ipsec might look like if

they were connecting two lands to make a

Wan

though the two networks have their own

firewalls and Protection Systems they

still have to connect the Republic

Network which we know isn't the safest

thing this is especially true in the

public network is the internet

Now using ipsec the two lands are going

to create a tunnel of communication

through the network or through the

internet this tunnel is secure and only

accessible by people inside their

Network the is ipsec tunnel by the way

is what we're referring to when we talk

about VPN or virtual private Networks

so when we set up ipsec the service

doesn't just configure itself

necessarily there's some things that

have to be put into place for the

services to run properly these are

called policies and policies is what

configures the services that ipsec

provides they're used to provide

different levels of protection data and

connections based on what in getting

what is getting passed through them in

other words just like with passwords we

have the passwords and we know they're

built into windows but unless we set

some sort of policy that tells the users

how their passwords have to function

they may not be used very well someone

might just use the password password

which isn't even a safe password so we

have a password policy that ensures that

people have a certain length uh history

and certain characters included in their

passwords the same thing sort of goes

with ipsec

now there are some important elements

that we have to address when setting up

ipsec policies first we have filters

that are put into place the filters

determine which packets should be secure

and which can be left alone

now every filter addresses a different

type of packet so there's generally a

good amount of different types of

filters all of these filters get

compiled into a filter list where the

administrator can easily change and

reconfigure the filters to address the

needs of their Network now again the

reason we're going to want to have

filters is because the more security

just like the more layers you have on if

it's cold outside

the more data it takes up

and the longer it takes to decode so the

less security we have the faster the

data is going to travel but the more

security uh the less easy it is to

tamper with so we need to weigh this

stuff like browsing on the internet

might not be something we need to secure

a lot whereas we probably want to secure

uh for instance email a lot more or even

Bank Social Security numbers

etc etc

next policies have to be provided the

proper Network information this involves

what security map methods connection

types and tunnel settings are being used

the security methods are basically

algorithms that are used in encrypting

and authenticating the data connection

types determine whether the policies are

going to handle

a local area network

a Wan or a VPN

in other words ipsec needs to know what

type of connection I have here so it

knows what level of security to put into

place you can imagine that with a wide

area network or VPN we need more

security than with a lan

all right so although this might have

been short duration we covered a lot of

important things first we talked about

the fact that ipsec exists remember

ipsec stands for IP security and it's

really not its own protocol what it is

is a series or a group of protocols

Services

Etc that ensure security over the IP

protocol or the Internet Protocol

we also talked about two of the ways we

do this one is the ah protocol and one

is the ESP protocol remember ah stands

for authentication header

as the name implies it's a header in the

IP packet that authenticates

to make sure the users who are about to

communicate are the ones for whom it's

intended and who are sending

ESP on the other hand which stands for

encapsulating

security payload

is literally going to encapsulate the

data in an encrypted form

and it'll only release this encrypted

information to someone who has been

authenticated to receive it and remember

to do this we use Keys both public and

private

we also discussed the three different

ipsec services that are provided

including data verification which

ensures that the data packets being sent

are coming from legitimate places

protection from tampering which ensures

the integrity

of our data that it has not been

tampered with either

tampered with from say an attacker

or the data might have just become

corrupted

finally we ensure that we're having

private transactions meaning that the

data is confidential between only the

people who need to be having it and

lastly we discussed ipsec policies some

of the things that we need to have when

we're creating our policies for IP

security for instance we need to know

the type of network we're on

and also filters

so that the appropriate level of

security can be applied to the

appropriate type of data

[Music]

welcome to module 14 lesson 1 denial of

service

so we're going to look at what is denial

of service by the way this is a small uh

subset of what you would get in the

competitive Security Plus exam and and

the network plus

um sorry the CCNA security exam those

are the vendors do security as well

obviously like a juniper but um company

is a good foundation and then in Vendor

specific Cisco CCNA security is

excellent you probably I think you need

to do the CC and a first or at least one

of the CCNA exams the um icnd one would

do check so what is it bandwidth attacks

connectivity attacks common types of

denial of service attacks what is

distributed denial of service

types of those difference between a

denial of service and distributed

reflective dos attack and then types of

reflective unintentional

[Music]

physical infrastructure attacks and how

to prevent how to identify denial of

service attack just bear in mind this is

an overview so you need some fairly

specific training on um hardening your

network and also identifying and

troubleshooting and resolving the denial

service attack

so what is it basically refers to an

attack on a computer network to make its

services unavailable to legitimate users

you've heard of it I'm sure in the Press

um

before some big big companies have been

attacked before Delilah service

basically attacks the network with

useless traffic

it's a type of cyber threat

so what do the denial attackers actually

put their effort into doing preventing

um legitimate users such as members of

the public or employees from accessing

Network Services

emails websites online banking Etc

usually the denial of service attacks

occur when the attacker floods a

particular network with a huge amount of

traffic

so for example to access a website we

type in the URL you send a request to

the web server

web server can only process a limited

number of requests at a given time now

there's a whole bunch of things that can

go on for example uh load balancing and

then CDN cloning the uh website copies

all over the web but even so

and there's only a finite amount of

resources dedicated to all these

Solutions and they can be used up

when the attacker burdens the server

we're too many requests the web server

is unable to process the legitimate ones

as a result you can't access it and

that's called the denial of service

good you can then Google denial of

service attacks and look at all the news

stories over the past few years

and messages to establish a similar

attack only limited the number of emails

are allowed in your corporate accounts

usually mind you even large

um free providers like Gmail have got a

limited amount of um storage

so as a result the attacker can stop the

users getting legitimate access to their

account

and in an email bomb the denial of

service attack the attacker send a lot

of spam emails and they disable the

actual email server rather than just an

account on the server

generally not concerned with stealing

information it's just quite an

aggressive way of bringing down a

particular service

it could be a person a business or an

entire company

they can attack and Destroy files in

affected computer system or Network

and some situations the Denali service

stack actually affects the website

um accessed by the users

most uh denial of service attacks are

aimed at the computers Network bandwidth

connectivity

our resources also server resources

bandwidth attacks on the computer or

network with a huge amount of traffic

huge burst of traffic legitimate users

can't access every network resources

the connectivity attacks harm the

computer with a large amount of

connection requests

available operating system resources are

quickly consumed and the computers

enable once again to perform legitimate

requests

another common type of denial of service

attack is a buffer overflow all devices

routers switches have buffers that

manage a temporary

excess amount of traffic

send and receive buffers and if these

buffers are actually overflowed then

depending on how the devices are

configured and what it is then it's

going to cause problems and packet loss

the sin attacks teardrop attack

Smurf attacks viruses a whole bunch

actually

the buffer overflow is the most used

distributes of a huge led to a network

more than the um buffer is um able to

handle

when the attacker has awareness about

the weaknesses of the target system or

network that's when you'll get a buffer

overflow attack and they can Target

certain vendors or certain devices such

as Cisco routers or uh the vendors

firewalls Etc

once when the attacker simply tries to

attack not knowing whether it's going to

work so it's a quite a Brute Force

attack

but for attacks are based on the system

or programs above their characteristics

and other way distribute emails

including 256 character file names which

all take a matter of amount of time to

process so the huge icmp packets

email messages including a from

statement that is more characters than

256 seems to be the limit for emails

now this is a sin and synark which you

should be familiar with from the network

of a plus and and the other network

research you've done this is what

happens before a connection can actually

take place if you're using TCP

so with a cell attack the attacker sends

a TCP connection request faster than the

Target computers processing speed using

client server technology it begins to

establish a three-way handshake

so you'd have a sin sinach sin and there

should be an acknowledgment happens

before the data sent

that doesn't actually happen

so client sends a collection

establishment using the sin synchronized

message

a server can then send a sin

synchronization acknowledgment client

responds with an act an act message and

the connection is then established

if the attacker sends repetitive sin

packets to every port using a fake IP

address the server establishes

Communications

and responds to all requests and what it

also does is it leaves a

a window open for the actual

Communications to take place so for each

request in request for a certain period

of time depending on the traffic it will

um Reserve resources

replies to each attempt with a synap

packet from every open port

okay teardrop account attack sends

fragmented packets to a Target computer

when the computer receives the packets

it's enabled to reassemble them because

of the following

a bug in the TCP fragment reassembly

overlapping packets

crashing of network devices

can usually happen on older operating

systems some of you might remember these

three Windows 3.1 Windows 95

Windows NT and some versions of fair

Linux

some Earth attacks is where the attacker

fluids the victim's computer with ping

packets the attack initiates the attack

by sending a ping request and then

spoofs the destination address ping

replies are sent to the victim's

computer address

since the Ping request is addressed to

the broadcast address all computers in

the network have to respond and

um each packet is opened and checked and

to see if it's the destination

as a result the victim can't receive any

genuine traffic because it's already

flooded with ping packets

uh technique of assigning a network

packet with a file side P address is

called spoofing

computer viruses these are distributed

and spread throughout the network in a

number of ways

the attacker uses and controls the

victim's computer to attack somebody

else's low and weak uh security network

security and some device some devices

you're waiting to have patches applied

to or they haven't rebooted after up and

downloading some updates or whatever and

this is when they become vulnerable

attacker floods they target competes

with a huge amount of data to a

particular site or spam emails using a

victim's computer so the name

distributed indicates the attacker uses

multiple host computers

uh this is to throw

um others off the trail and make it

harder to actually identify the attack

because the um victims are actually

legitimate systems on the hosts

the attacker can increase the

effectiveness using client server

technology

in distributed denial of service

master program or software is installed

on one computer normally they use a

stolen login credentials

now it may not happen immediately but at

some particular time the master program

communicates with other agent programs

that install the computers anywhere on

the internet

when the ages receive their command they

start to attack

the master program is able to spread

thousands of agent programs within

seconds using client server technology

so some characteristics of distributed

denial of service attacks a botnet

traffic spite coordinated attack

so if you can see that there's a

attacking machine at the top there and

handlers and compromise systems

um going down to the targeted services

or servers on the bottom there

so botnet refers to a group of computers

that can cooperate

also known as zombies in this context

at the botnet owners also known as

herders they manage computers in their

botnet botners used to send spam emails

or to participate in distributed denial

of service attack

so this is why it can be so difficult

because all these legitimate devices at

some point of time when there's a

trigger it's a like a timer or it's time

when everyone's off work or on a

Saturday night on a bank holiday they'll

start their attack

traffic spy overloads the victim's

Network or server in order to

its services and resources

as a result the legitimate user will not

be able to access the service

they use when people are coordinated to

carry out the attack on a site or site

at the same time

when many people attack the server the

web Server slows down or gets overloaded

it's difficult to differentiate such

attacks from the normal traffic

where many people do this at a similar

time the web Server slows down or gets

overloaded

uh it's difficult to identify this a

type of attack from normal traffic that

can happen and obviously you do get

spikes on networks and then if there's

updates been applied

to the servers again it can

um appear to be slow legitimately slow

difference between denial of service and

distributed

and using a single internet connection

an attacker can harm a network in a Dos

attack

launching multiple connected devices

that are distributed is a distributed

denial of service attack

uh the distributed another service also

differs in the attacks that perform

using botnets

um including mobile phones routers PCS

Etc

Denali service attacks can harm a single

machine or they can attack an entire

network

moving on to the reflective Amplified

denial of service

the reflective user third-party machines

to attack a targeted computer so

basically the is one way for the

attacker to mask their identity

reflective denial service attacks use

third-party servers for example DNS

servers to attack a targeted computer

the attacker sends a requested the

reflector server or servers with the IP

address of the target

and what it does is overpowers the

target using response packets

an example is a DNS response

type of reflective denial of service

attacks DNS amplification Network time

protocol smurfing

mentioned DNS amplification the attack

explicit DNS server to make

um change small requests into

considerably larger payloads this can be

used to overthrow the victim's servers

Network time the attacker exploits a

widely accessible Network time servers

and destroys the targeted computer with

UDP traffic which is what ntp uses

uh can they're not all intentional they

can be unintentional this is when a

server crashes for example can't provide

services because of traffic from

legitimate users

uh again have a look there's a whole

bunch of quite

um well reported and embarrassing

examples for government and private

companies large companies

so in a popular website hosted news on a

less equipped secondary site the server

on that side won't be able to handle the

traffic especially if there's a big

breaking news story going on

a person physically attacks the

infrastructure of an organization when

it's a physical attack

example is they snip or destroy a fiber

optic cable

again these I suppose these could be um

malicious or accidental or known quite a

few cases of work people cutting through

cables by accident

if the attack is able to access the

compute system

then they can obtain information on the

computers obviously

there's no set way to rescue computers

or a network from these type of attacks

you can put into place certain steps to

reduce the likelihood

install to maintain an antivirus on your

end devices you can also have antivirus

on your

mobile phones firewalls and computers

and configure them to control the

incoming an outgoing traffic

protect emails from spam they're just

the latest uh hacking on the Democratic

National Party actually where a guy

received a link telling him to reset his

password and that went off to some

Russian site allegedly somewhere who

then got into his system and read all of

his emails and all the other emails for

all of the people on the site

and it will manage unwanted traffic and

send alerts for spam email messages

you can install a intrusion detection

system an IDs that will protect systems

from the distributed denial of service

attacks

the RDS uses collection verification

methods

and speak to whatever your network

equipment vendor is for more information

you can disable and use networks or

segments or devices or ports on switches

regular system performance

and now you can have legitimate issues

that represent denial of service like a

fonty faulty network card a spanning

tree issue

a routing protocol convergence when

you're either booty devices or a network

has gone down or up

and large file download by a user on the

network who doesn't have a limit

a bulk email sent for marketing for

example

unusually slow Network I know and some

networks I've worked up at for example a

Friday afternoon there was a big backup

and the whole network went slow but if

that happened on another time of the

week then it could be a warning sign

unreachability of a particular website

High numbers of spam messages received

on an email account

denial of service oh we've just

summarizing what we've covered is

deniala service bandwidth attacks

connectivity attacks common types of

deniala service and what is distributed

to Denali service

types of distributed attacks the

difference differences between the two

reflective denial of service types of

reflective unintentional

attacks on our physical infrastructure

and then preventing denial of service

and identifying one when it happens so

that's all for now thanks for watching

[Music]

welcome to module 14 lesson 1A common

networking attacks we've heard earlier

about a few attacks but we need to just

update the list because of the new stuff

in the syllabus

you can look at Social Engineering

Insider threats a logic bomb

Rogue access point Wireless

evil twin

War driving could love to know who comes

up with all of these names

uh fishing

around somewhere DNS poisoning ARP

poisoning spoofing

de-authentication Brute Force

VLAN hopping man in the middle

and then some exploits and

vulnerabilities social engineering the

funny thing about this threat is it

isn't um electronically detectable so we

don't have a little alarm go off

somewhere it's um normally when an

attacker convinces an employee to

disclose confidential information so

what happens is uh perhaps they could um

say they make a phone call that it goes

through to

um

headquarters office and then they

um they asked to be put through to your

office so what you'll probably see on

your phone is the extension one two

three four as if it's coming from here

so you think it's an internal call and

but really it's coming from outside here

in the um the EU the hackers house

wherever they may be so it looks like um

uh the legitimate call

they pretend to be a senior manager or

someone inside the tech support

department

and um they'll access some information

they'll ask you for passcodes or say

there's a problem with your account and

um this is a pretty successful way of of

getting information

the other thing is

um or accounts are social engineering is

somebody Who Walks Behind the employee

who's already entered the security guard

for a door also known as tailgating

also another way is leaving the USB

ground on the USB on the ground

somewhere this is quite common sometimes

this these USB sticks have actually got

a battery in and it's designed whatever

whatever device you plug it into sends

an electrical current through it and it

fries your circuit board and Fries your

hard drive or it can actually plant some

lines of code

Insider threats normally an employee or

a contractor

they could be under duress working for a

competitor or a blackmailer looking to

get information

and most security focuses on external

threats so it's looking at

incoming attacks

malware Trojans all that kind of stuff

but inside your organization obviously

you could have people that are posing

the threat

so people who work for your organization

should know your systems policies

procedures and weaknesses and they

should know how to spot somebody Who's

acting suspiciously or acting for

suspicious information

as you've probably seen in the movies

you could have what's known as a sleeper

so we normally uh

associate this with spies sleeper agents

let's sleep with somebody who could be

waiting to be activated

obviously they could easily go

undetected and they could be doing

um things to your network or passing

information for some time

a logic bomb is a type of malware

it does damage after a certain condition

is met so an example is

um the spyware or the the malware sorry

is on your device

and then when the clock ticks over to

the first of the first say 2019 or

whatever it then executes the

it executes the code and then does the

damage

it can be left behind after attack and

what it could do is destroy any evidence

that is taking place so it could destroy

whatever fires it's actually put on your

system making it harder for you to do a

forensic analysis

you may remember the Chernobyl virus

this was an example of a logic bomb

they wrote to the boot sector of discs

swipe the bias on the hard drives and

left the devices unusable

so pretty bad

uh Rogue access points so we're talking

about the um waps wireless access points

major concern especially in large

environments

so somebody's brought in a third-party

access point by Network user often this

can happen when somebody's complaining

about

their signals you've got you know you've

got bars on your device so you've got

one or two bars then I've seen instances

where people have brought in their own

access points and somehow managed to

connect to the network and they get

obviously a higher connection or faster

connection

so gives a network access to anybody in

range of the Rogue access point so this

is the the danger of people who uh on

purpose or just accidentally they don't

know how the technology works a lot of

other devices will be associating with

this access point here when it should

have actually gone off to the corporate

one

you mitigate this for regular site

surveys basically you're walking around

with um your wireless wireless device

checking for legitimate devices

uh you can force users to authenticate

user NATO 2.1x

uh also can happen if you enable Wi-Fi

sharing on your phone so if you're stuck

somewhere you've got your smartphone

there's a little

um app in there where you can let the

devices say for example your laptop if

that doesn't have a capability it can

actually piggyback onto your

um phone with a wireless signal

and then connect to the network so

you've got to be careful of that

Wireless evil twins this is uh configure

an external access point to behave as

The Trusted access points

it used the same SSID

and their security settings

so it'll all look the same

and the user connects you can see the

the legitimate one is here but the

signal is pretty weak the signal here is

much stronger so you'll more likely

connect to the Rogue access point

this device normally will have a quite a

strong signal on purpose so it is chosen

of the legitimate one

again this can be brought in by Network

users innocently or it can be done

maliciously

mitigate with https or VPN tunnels

while driving is just simply this

happened when Wireless first came out

and nobody had security or it was just a

very weak security people drove around

trying to find some wireless access

somewhere and

um

if they could see your device and

connect to it even when I it wasn't too

many years ago and my my internet went

down and I um I could see on my wireless

um if you do a wireless search you'll

see

a few padlocks

and then um you'd have one with a open

padlock and you can just you could

connect to that so you see it less now

because most of them are configured

quite easily for security

fishing email sent which is looks

legitimate usually appears to be from an

official website and it asks you to

click on the URL so you click here the

sort of things I'll see are

it'll say Amazon or um

text message

and even smarter people have been caught

out say for example if you're like me

maybe every three days you've got an

Amazon delivery coming or um or

something from eBay so if you're busy

you'll see it I think oh no I've missed

my Amazon delivery too late you've

clicked on it and um the damage has been

done

fishing can be phone based also you come

to this with email security systems spun

viruses fishing Etc

ransomware has really been in the news

lately because even the law enforcement

agencies have been caught it's taken out

large areas of um the National Health

Service in the UK

it limits all of some system access and

it locks your screen as it does here

until you've paid money to the extorters

offers threatens to publish your data

and if in the case of uh

I can't remember what it was some sort

of police department anyway but it

accessed all of their systems somebody

downloaded or somebody got an email uh

opened it up

and um they downloaded the software and

it spread through all the all the

devices

often uses cryptocurrencies for payment

so it's hard to trace the money

I often uses Trojans uh wannacry the uh

one of the latest ransomware

that uh malware

um software packages that came out

automatically transferred it didn't use

a Trojan

DNS poisoning we've already learned

about DNS this is a fake DNS cache entry

it cropsy data inserted into your system

and the name server returns a false

result so you'll do a DNS lookup it goes

to your DNS server but for whatever

reason this attacker has somehow

injected this fake entry and instead of

going off to the real server here it

queries the fake one and it just for all

intents and purposes to you looks like

you're actually on the correct site

obviously then it'll try and get

passwords usernames or credit card

information and again this false entry

here if you've got a DNS server it can

actually propagate within your depending

on the authority of This Server it'll

propagate to other servers

up poisoning

requires the attacker to have access to

the victim's local area network again

this could be a contractor or somebody

who's managed to get in somehow it

provides a host of the wrong Mac address

for hosts the host IP address so

um if we go down here this host is

looking for the you can't say it can't

encapsulate the packet as we already

know until it knows the MAC address so

there's a field here for layer three and

then but for Layer Two in order to send

the packet out it needs to know the Mac

and if it's got a the false entry here

from the attacker then it will send it

to the wrong host it'll send it to here

instead of here or vice versa

you combat this with Dynamic harp

inspection which is you will enable this

on switches

our and DHCP snooping

there's a lot of different type of

spoofing when it comes to hacking this

is pretending to be someone or something

you want

and one type of spoofing is DHCP

spoofing the idea is the software

exhausts the pool of addresses so you'll

have a pool of say

10 000 addresses and it will spoof keep

requesting the addresses until

eventually there's zero left at which

point in the DHCP server can't allocate

information and then hosts on your

network can't join the network

uh the Mac impersonates house or device

on Two Hosts on one switch Port so this

is actually poisoning it looks like the

port on the switch here it should have

one Mac address per port

but

it's got two associated with the uh Port

which um

it can it can happen if you've got a um

Hub plugged in but it would you would

normally have this on your network

however the ARP Source the MAC address

is disguised and the arc cache is

poisoned

de-authentication this is used on Wi-Fi

networks this is more of a pain than

anything it sends a de-authentication

frame to the host to end the session the

attackers boosts the victim's Mac

address which you could attain by

sniffing while a sniffing now there's no

need for encryption so even though

you've got an encrypted uh connection

so or your device or all your traffic is

encrypted the de-authentication frame

doesn't have to be

so whatever that frame will say

whatever whatever it says in the frame

to tell it to terminate the session that

doesn't have to be so it's a floor in

the technology

brute force uh this is a type of

password attack the other type is a

dictionary attack so what the Brute

Force attack does it just keeps guessing

over and over

to try and find the password

typically the username would have been

installed and

um yeah you'll have a hashed version of

the password this is what it's trying to

guess

the same hashing algorithm is used for

example md5 is used

and it will use this to try and send

hash values

you'll combat it using Advanced

algorithms so you'd have like millions

or billions of combinations

um for example RSA or public key

encryption

VLAN hop in uh host typically require a

layer 3 device to reach under the VLAN

and if I've got a picture of this

actually but we've seen before if you've

got a hosts

in this VLAN

and they will connect to a switch and

then hosts in this VLAN

so VLAN 10 VLAN 20 and they'll be

they'll have different IP addresses but

uh these do these devices can't connect

to one another unless the switch is

connected to a layer 3 device now this

can actually be built into the switch it

could be a multi-layer switch but it has

to have this layer 3 capability

well VLAN hopping the attacker attempts

to bypass the layer 3 device to com

compromise another device and you could

have all your security

or some of your security built into this

layer 3 device

here it's done by a switch spoofing or

double tagging

so switch spoofing the device

impersonates a switch whatever this

Rogue device is it's pretending to be a

switch so probably we'll need a trunk

link here

you combat it by disabling trunking

where not required

to say this is your frame here and you

would have your VLAN

uh 10 here and say 20 here well normally

when the frame reaches the destination

the VLAN tag is removed because the

hosts don't really care that they're in

a VLAN but what they can do with VLAN

hopping is they can add an extra one

um here in order to gain access to a

VLAN when this device might be over here

on VLAN 20.

so that's double tagging

combat by using a dedicated VLAN for all

trunk links

so your trunk link between this switch

here

is switch here this switch here you've

got a special VLAN only used between

these trunk links so save VLAN 101 102

103. these these numbers aren't used

anywhere else on the network they're

just used for the trunk links

uh this is just a diagram showing you um

the double tag frame here so the switch

arm removes the first tagging forwards

to switch to and this time

the tag is still attached to it

man in the middle attack uh convinces

the sender and receiver that the

computer in the middle is the actual

host so this host here thinks it says

speaking to the server the server thinks

he's speaking to this host over here

really it's going between this

intermediary device here which is the

attacker

you normally accompany this with DNS or

ARP spoofing so there'd be an ARP cache

here

and here and it would say the back

address for this particular host but

really it's injected a false Mac address

here

and it and the messages are actually

sent and received

so there's acknowledgment it sends and

then this device here will send out an

acknowledgment but really it's going

through the middle here

type of spoofing attack

I've renderability scanning

um

this should have appeared in a moment

sorry it probes the host in order to

find an explode exploitable service or

process so you've got your server here

and obviously there's ports permitted or

denied but it will keep probing until it

finally finds one that's open and then

it will try and do some damage

there's a whole bunch of tools if you do

an ethical hacking course for example

you can download there's a ton of free

tools that um the idea is you're trying

to learn how to protect your system but

they're obviously available for use by

hackers

now say there's a particular Port open

or a service so

um like an instant messenger Port has

been left open

this will then tell the attacker the

hacker what type of attack will work

best on this particular Port so it may

not use that specific pool but it may

then be able to Target a vulnerability

in the application

one of the tools you could use is a nmap

you obviously counteract all of this by

doing some penetration testing or paying

for it

and here's a result from the nmap tool

here

and then it's giving you your your

outputs you'll learn more if you do

penetration testing which isn't really

covered in the syllabus

all right so we've covered a lot of

stuff social engineering Insider threats

logic bombs the Rogue access point that

somebody brings in evil twin driving

around looking for a free wireless

fishing

uh ransomware poisoning the DNS entries

the ARP cache spoofing is pretending to

be something or someone you're not

D authentication the frames got

um it can be in clear text Brute Force

attacks VLAN hopping man in the middle

and then exploits versus vulnerabilities

that's all for now thanks for listening

[Music]

thank you

network security threat mitigation and

user education

we've now talked about a lot of the

different types of attacks and security

threats that you encounter in today's

world when it comes to your network and

we've talked about ways to protect from

these threats from attacks to antivirus

software and so on but let's talk a

little further about how we can mitigate

these threats and if that word is new to

you the first thing we're going to talk

about is what threat mitigation means

we're then going to identify some of the

steps in a good protection strategy

these include developing strong security

policies monitoring the threats on your

network something that we've talked

about in the past a hugely important one

educating users since almost all the

threats we've talked about in some way

shape or form have to do with what we

call social engineering

in other words getting someone to do

what you want them to do for instance

give them your password

automating scanning and updates both

from uh updates of the operating system

and from the virus scan program and

patches and updates for our operating

systems and our software

so what is mitigation one of the only

ways that a network can stand a chance

against attacks is to do something

before the attack is made isn't it said

that an ounce of prevention is worth a

pound of cure well this means more than

just having anti-virus and firewalls in

place those things are great but they

can only stop an attack that's already

being made really the best way to

protect a network is to set up

prevention measures before an attack can

happen

the idiom of an ounce prevention is

worth a pound of cure means that you

save a huge amount of trouble by

preventing the trouble from even

happening so one of the best ways to do

that is to mitigate the threats that are

made on your network mitigation is a

word that doesn't just apply to

networking but in this case we're

talking about it in the sense of

lessening of a chance of an attack by

using mitigation you're taking measures

to reduce the frequency of attacks the

size of those attacks when and if they

take place how severely most importantly

they're going to impact your network we

need to have a strategy in place in

order to mitigate threats and make life

on the network easier

so step one of the mitigation strategy

needs to be to set up rules and policies

within a network users are set up by the

administrator and need to be agreed upon

by all the high up people on the network

and all the high up people in your

corporation they then need to be told to

all of the users these rules should be

standard throughout the network with

very few exceptions because these

exceptions easily lead to a breach in

security

one of the rules that needs to be set up

for instance is what can users download

such as applications can they download

stuff like browsers well some of them

are trustable but are we going to trust

people on our Network to choose the

browsers that are actually worth

trusting

the administrator needs to be wary of

just about any program that a user could

download and as we learned in the last

module viruses can hide within programs

they don't just attack out of nowhere a

user on your network could easily

download a virus without even knowing it

and then they end up infecting not just

their computer but the entire network so

a rule needs to be put in place that

says whether or not downloading of

applications is allowed and if it is

from what sources you may even want to

limit the fact that people can download

by shutting off their user rights to

download or to install programs on their

network if they can't install anything

they can install a virus another major

Rule and this is really important is are

they allowed to use outside storage

devices such as uh removable hard drives

thumb drives flash drives and storage

CDs any one of these media storage

devices can contain malware one of the

uh classic examples is

someone leaves flash drives in the

parking lot when you find the flash

drive what's the first thing you do oh

you say it's a brand new flash drive I'm

going to put it in my computer I want to

test it out see what's on there see if I

can find the owner well the minute they

do that they've just infected your

system and your network with a virus so

we need to make sure that even though

the person might not be

trying or mean to infect the network

they could do it simply because they

don't understand the risks that are

associated with flash drives and outside

storage media they might also be

bringing stuff from their home computer

which very well could have a virus on it

so storage devices could contain malware

without the user even knowing it and

this isn't something you want to risk so

a policy is really important

other things such as this would include

stuff like tailgating when someone logs

in

uh swipes their card to get into a

building in the morning if they open the

door for someone else well now that

person just got in without being audited

we didn't have they didn't have to swipe

their card so that's a pretty major

concern when it comes to security

another one uh is something like

shoulder surfing or giving out your

password we need to make sure the

policies of how passwords are reset when

they're reset and who you can give them

to is fairly important if I give my

password to my wife and suddenly my wife

becomes my ex-wife she could do some

major damage to me and to my company by

using that password to get access to

private information

so step two is a mitigation strategy

which is to constantly monitor virus

threats as you might already know

attackers and computer hackers are very

well educated when it comes to getting

around security systems This Is How They

infect networks and when their attacks

are blocked most of them just update the

attack and try a new version they don't

just stop so this is why the

administrator needs to be as on top of

the virus versions and attackers and the

threats that are out there it's up to

the administrator to make sure that

they're up to date and research is being

done and they're knowledgeable at the

newest attacks that could be coming to

their Network again it's no one else

that's going to get blamed except for

the administrator when someone hacks to

the network so not only do we need to

monitor our Network we need to monitor

the threats that are out there and this

really involves doing research on what

the latest and greatest techniques are

to hack into a network

step three is user education which is

really I think the most important step

that we have out there it's critical to

have Network users educated in this

field so that they know exactly what

sort of threats are out there and what

safety habits are there as well there's

some safety habits that are obvious like

locking a device and keeping your

password secure but there are other

security measures and knowledge that's

less obvious but just as important

Network users need to be knowledgeable

on how to protect themselves from

viruses and how to recognize them so

they don't just click on something when

it pops up on their browser first they

personally need to back up their

important data because in the event of

an attack perhaps are

major system goes down alternatively

they need to know that they should be

um backing up their data to perhaps a

central location or they need to be

taught where to back up their data for

instance to the network share and not to

removable hard drive or not on their

desktop because if they back it up to

their desktop then what happens when

their computer gets broken now they've

lost all the work they didn't back up

automatically to the server they also

need to be diligent about web browsing

what they download what they click and

so on if they're administrator is going

to allow them to download programs they

need to be careful about where they

downloaded them from again we always

have this

interval between responsibility

and power the more powerful you are the

more responsible you have to be if I can

install things on my computer that also

means a hacker could use my information

to install something on the computer as

well and finally if a if they download a

program that seems illegitimate or they

think they've been attacked they need to

be able to spot the issue and report it

to the administrator before the risky

program has a chance to damage sometimes

they don't want to say anything because

they don't want to get in trouble but if

they had said something earlier we could

have prevented more damage it's really

important for them to know when they are

being deceived by something and when

something is legitimate so I see this

all the time people send up these emails

saying beware of this and an easy Google

search would show that the thing that

they're actually being aware of isn't

real it's something fake and they've

spent time and energy everyone's time

and energy getting worried about

something that actually is not going to

affect them on the other hand they don't

seem to recognize when someone's account

has been hacked and is asking for money

money when that person would never do

that it's not characteristic most of all

they have to check and double check

stuff and be willing to ask questions

so here's an example of an extremely

common virus that's intended to scam

people out of money on the on the

computer that's being infected the virus

takes over your computer and only lets

you see this screen or one very similar

to it it claims that the IP address has

been used to do very illegal things and

the FBI sees the computer and in order

to unlock the computer you have to pay a

fine or purchase a code now this virus

is extremely intrusive and obviously uh

quite

you know

um

successfully convincing look at all the

7-Eleven CVS Rite Aid all the logos at

the bottom Department of Justice Etc and

the reason they're gonna make you pay

through money pack it looks so real is

because that way they know they're

getting the money on the other end so

it's important for someone to recognize

that this is actually fake look on here

it even scares people by saying you have

72 hours to pay the fine or you're going

to be arrested

now someone might have been doing

something like downloading uh a torrent

off the internet and so they think oh my

God I'm gonna be in trouble and they

don't want to tell you because they

think they're going to get in trouble

with you as well we need to make sure

that they have a judge-free Zone in

which they can come tell someone and

that way you could remove the virus and

they could go on on their way and

continue to work

now as viruses and malware attacks

become more and more advanced anti-virus

software improves to combat them there

are thousands of antivirus software and

some are more advanced than you could

possibly even imagine it's not at the

ordinary however for antivirus software

to have automatic features so step four

in the mitigation strategy needs to be

to make sure that antivirus systems and

software are configured to do things

automatically this means they have to

automatically scan the computer scan the

network and update themselves we don't

want to rely on a human to do this very

often when it comes to virus scan

nothing's going to be rolled out

automatically that's going to damage our

computer so this stuff needs to happen

automatically when are we going to scan

the network well we want it to scan when

no one's doing anything so we want to do

it for instance at 2 am not at 2PM when

people are busy opening things and

closing things and that's when the virus

scan program won't be able to get access

to fifty percent of the network and

therefore something could be hiding out

this eliminates all this eliminates the

human element it allows for more regular

and controlled updates in the process

which is important because when we allow

humans in that's when errors occur

finally when an update to a program is

released it's generally to address bugs

that were found within a previous

version along with these bugs there

might have been some security weaknesses

in the software that need to be

addressed but program updates don't come

out very often in between uh updates

patches and so on there might be a

temporary fix that's released or a fix

that is manual that have been found so a

patch does exactly what you think it

does it basically covers a hole in the

software and temporarily repairs it

until an update or a new revision of the

software can come out so as soon as

patches or updates are released the

network admin needs to look at them and

think about installing them on the

network now notice that I don't

necessarily want you to just install it

right away

I want you to test it

and think about it

because the patch or update could very

well cause another problem on the

computer and one thing we don't want to

do is bring down our system because we

put in a new update that suddenly stops

our printers from working or something

so we need to balance this with the idea

that once the patch and the update is

released the hacker now knows that this

is something that they can exploit and

so the longer you wait to update it the

longer you're at risk of being exploited

all right so we talked about a bunch of

things in this module some of this is

common sense but these are things that

pop up on the network plus exam

first we want to Define Network

mitigation mitigation the word literally

means to lessen

and so what we're doing is we're

lessening the threats that can hit us

some of the steps that we identified in

this strategy were first to develop

strong policies for instance a password

policy is important

download policies

internet use policies

and so on and so forth we also need to

monitor threats not just internal

but we need to research what's going on

around the world so we know what the

latest things are that are attacking our

systems

the most important one I think is

educating users social engineering is

how hackers and attackers get around the

human element when there's a human

element there's a flaw and so we need to

educate users so they don't click things

that look bad and they know

when to ask questions since this can

help them as well

we also want to automate scanning and

updates from virus scan programs and

perhaps our firewall this should all

happen automatically

because if we remove the human element

then there's not going to be an issue we

also want

scans to happen in the middle of the

night when no one else is using it for

instance 2 am or 1 am make sure that you

give enough time for the scanner to

actually scan the entire system

finally we need patches and updates and

we want to balance

the patches and the updates with uh the

patch actually doing harm

versus the weakness

or exploit that it's correcting

the longer we wait

to employ a new patch or update

the longer we're at risk

[Music]

thank you

welcome to module 14 lesson 2A Advanced

threat mitigation

so this is new stuff for the um double

07 version of the com2 exam managing

your signatures hardening your devices

in terms of security that is changing

your native VLAN

switch Port protection

restricting access with access lists

Honeypot and honey net uh penetration

testing so signatures in terms of

signature management we're talking about

IDs and IPS which we've covered earlier

the signature-based detection examines

Network traffic for pre-configured and

predetermined attacks so the signature

is the thing that is matched against in

these devices the threat the threat

signature

these are known as signatures attacker

um convinces employee to disclose

confidential information

if adult signature is identified by the

system an alarm is triggered or the

traffic will be blocked this it depends

on how you've configured your

um IDs and IPS so it will either

um send an SNMP alert or create some

sort of log message or whatever you've

designed it to do the signature codes

are updated or they should be updated

regularly for new or false patterns you

don't you really don't want false

positives either because it's just going

to be in traffic's blocked when it

shouldn't be

uh there's a website called threat

threatconnect.com they offer some sort

of signature management uh system for

for you to look after all your

signatures uh I I only suggest it

because I use their graphic and I wanted

to credit them for that but this is what

came up when I was researching threat

signatures

device hardening this is part of your

daily weekly monthly admin task

especially if you're in charge of

security

for uh looking after your network

you'll Pat your update software or

firmware in your Hardware devices

check for non-compliant passwords this

will obviously part of your password

policy but I'm sure you've logged into

something or had an email updating you

saying that your current password isn't

um strong enough and you need to update

it

removing redundant networks and IP

addresses strangely enough I've known

equipment found years after people

thought it had been decommissioned it's

sitting in a office somewhere plugged

into the network and nobody knew it was

there and this can then be a back door

for hackers to find and get into your

network changing security keys

are changing the native VLAN so the

native VLAN is used for any untagged

traffic on your network you'll be

familiar with this when you start doing

Cisco configuration or any type of

juniper or the other network management

big security vulnerability your native

VLAN is passes important information

such as

um your Cisco Discovery protocol or the

equivalent which is device information

foreign

your operating system that it's running

etc etc a dynamic drinking protocol is

for uh trunking so your native VLAN will

normally go across a trunk link and

you've got all of this important

information

on The Cisco devices certainly and

probably a lot of other vendors the

native VLAN is VLAN one and if you leave

this as the VLAN that the switches can

communicate with you've left a possible

security vulnerability

because this traffic is actually

untagged

so what you want to do is on any drunk

leg trunk link you change it to an

unused VLAN

so this is one that isn't been used on

um

so you've got to VLAN 10 20

30 and 40. you would use your an unused

VLAN on your trunk links for example

um

two two two just something fairly high

and then another trunk link to another

switch

you'd have another VLAN for example two

two three

Etc

is the output for a Cisco device and you

can see this is trunk in so it's passing

multiple vlans on this link but the

native VLAN is uh VLAN one

so I've wiped over it there the native

VLAN is VLAN one which you don't want so

what I did I went to the trunk interface

here I issued the command switchbot

trunk native VLAN five

you'll probably use something higher

like I said like two two but it's just

to illustrate the point so this traffic

that passes over uh the native VLAN will

use VLAN F5 it won't use VLAN one and

you've got to be careful because you

can't delete a VLAN one it's there all

the time you just don't have to use it

to pass any traffic and now you can see

it's changed from VLAN one as a default

to VLAN 5.

I've already mentioned all this sorry so

another thing mentioned is bpdu guard

this is arrived in the syllabus

a bpdu guard it's on an interface the

port is every disabled when a bpdu is

received so Bridge protocol data unit we

talked about earlier this is uh used for

spanning tree traffic

and it can actually change your layer 2

topologies for example let's say this

switch is the root you've got a high a

high-powered switch here and it would

normally be a multi-layer switch here

and all of your traffic is pointing to

this device but what will happen is this

device will announce a number

to say I am the boss and say for example

this is number 99. this is the number

that determines the root of all your

spanning tree traffic well what happens

is if this device uh connects to the

network say you've bought you've found

it on a Shelf at work and for some crazy

reason all you've done is plug it in and

this has happened by the way I've seen

it happen well this device could

actually be configured with the number

100

in terms of um spanning tree and what

could happen is then or this could be a

really low switch is worth about say a

hundred dollars and it's just got a tiny

amount of process and power all of your

spanning tree traffic all of a sudden

will be converging onto this tiny little

switch the CPU will go from almost

nothing through the roof it'll probably

crash bring you down your entire local

area network and at that point you'll

probably be out of a job to be honest

so what happens is with bpdu guard you

configure it on this interface here for

example fast ethernet and 10 and if a BP

do you frame is seen coming in onto this

particular interface it will error

disable

um it will error disable it and it won't

pass traffic until you the network

administrator

um what come comes shuts it manually and

then manually no shits the interface so

you have to re-enable it

uh root guard

so I mentioned uh if this is a topology

where it's actually I think from my CCNA

book where I'm telling you on what

interfaces depending on the topology you

would add bpdu guard root guard you

would add down here

on these level of interfaces so these

are your layer 3 switches and these are

your these images here represent Layer

Two

uh root guard is configured per Port so

you wouldn't configure it on a device

and expect the configuration to be

passed out through your network

and like um other configurations root

ports are the closest to the spanning

tree master these ports are furthest

away if this is the master here in my

topology

these are the ports that would normally

you would want to be root and it's

basically saying the root equals

um best

path to take to the master this is not

the best path to take to the master this

would cause you a lot of problems this

is why you would enable root guard on

these ports here

so Modesto for incoming Bridge protocol

data units

and it prevents support from becoming a

root Port how it does it yeah you can

learn a bit more when you do Cisco CCNA

and ccmp Etc

DHCP snooping this is the uh legitimate

one

here this is the Rogue that somebody's

either somebody's attached it to your

network or they've downloaded some code

accidentally onto their device and it's

trying to take over as a DHCP server for

this segment of your network which you

don't want to happen

it forces the switch here to examine and

filter inappropriate DHCP messages so if

this port if this switch detects it

coming on this port you've configured

this port here as interested

and you know which ports you trust

because you're the network administrator

this port

so it comes in and that is permitted

through untrusted it comes in and

blocked and then you would normally get

notified as the administrator that hang

on something's not quite right here with

a text phone call or other type of alert

uh vlans these separate your host into

function so here you've got the sales

team you're accounting uh Team the IT

team and then your human resources and

what this does and it depends on the

design methodology you're following by

the way there's a whole bunch of ways to

design your network depending on which

vendor you're speaking to but we've

separated ours into functions

now if there's a broadcast say there's a

a fault on the network card for this

device here

then um the broadcast traffic because

each VLAN has its own network address so

say that's in 10.10

uh 10.20

10.30

and uh

10.40

so these are all different

um subnets and in order for these to

communicate you'd either have to have a

layer 3 module in this switch or the

switch would be connected to a router as

we've spoke about earlier if there's a

broadcast through this faulty network

card here it's basically restricted to

all devices on this VLAN

and then what would happen is the the

your phone would go somebody would call

tech support and

um it would help you in your

troubleshooting because the broadcast

isn't affecting everyone here but

basically you're told that um everyone

in the sales team is getting a really

slow Network response and then this this

um this is known as the divide and

conquer method of troubleshooting you

know that everyone here is affected

and then so you'd be looking at these

ports on the switch you could use a the

sniffer the network sniffer and you'd

probably quite quickly see the IP

address dot one is sending out normal

about traffic and then it's gone through

the roof whereas all the other devices

on this particular and segment of

sending a normal amount of traffic

access lists and these can be used to

block an entire network or subnet one

particular host or a number of hosts a

particular port number or a protocol so

um icmp or

um

whatever you want

airport numbers could be anything dhep

DNS host dot one and then obviously

entire Networks

so it's a list of permitted or denied

traffic so if you don't worry about the

uh text here because you're not expected

to know this for the exam you've give

you've created an access list and you've

said do you know this traffic icmp and

permits IP traffic and what happens is

the access list always processed top to

bottom I've only got two two entries on

this so it'll be pretty quick actually

but as soon as the access to this reach

is aligned so say it's icmp traffic it

would reach this particular line

and then it would be a match and it

would be denied the access this wouldn't

go all the way to the bottom if it's not

icmp traffic it would reach the next

item on your list and the chances are

it's going to be some other sort of Ip

traffic and it would be permitted

honey pot honey net honey pots attract

possible attackers into an isolated

environment

so this is your attacker and it's a

potential victim and what they don't

know or they should know is they've

actually been fooled into redirecting

into this

um new net system they can't do any harm

in this place and what you can do

is this is a pair of binoculars I know

it's absolutely Dreadful isn't it

this is you as the network administrator

watching what they do you'll obviously

be doing it via whatever software and

you can see what commands are executing

and trying to inject pieces of code and

this whole environment here is um

protected is segmented off from your

network and then that that lets you

design a series of steps to protect your

network so you're analyzing the behavior

and Gathering the information if it's a

honey net it's basically a chain of

Honey pots so you've got you've got your

honey pot here and but what you've done

is you've chained them together for

whatever reason

I usually place in um Network segments

this will this will be isolated by your

firewall so they're coming in and they

get redirected to your firewall this is

actually your local area network over

here

sting uh comment here have actually got

the um

the pen test certification out I'm

looking into adding it now

um so keep your eyes open it scans your

network in order to find ports or

protocols with floors I've talked about

this kind of stuff before part of your

regular security ordering and audition

process so say every every Monday you

carry out this particular

um test on your network

it can simulate a type of attack and

um it's well recommended that you you do

this so we've covered a lot of stuff

here

um managing your signatures device

hardening changing your native VLAN must

do protecting your ports

we looked at um

protecting it from the STP packets

coming in the bridge protocol data units

so we don't it doesn't become a root

or um and it doesn't change the

um it doesn't become a report and it

doesn't become the STP

um root either both very bad things for

your network

access lists Honeypot and honey Nets and

then penetration testing so that's all

for now thanks for watching

[Music]

welcome to module 14 lesson three

policies and best practices

a few things we want to cover here the

privileged user agreement your password

policy

on off-boarding

which is when people join your business

and leave whatever reason

your licensing restrictions restrictions

International export controls

preventing data loss and remote access

policies

incident response policies bring your

own device

acceptable use policy your

non-disclosure agreement

uh system life cycle and safety

so your privileged user the privileged

users are people you could call them

super users or administrators whatever

this um agreement should be signed by

administrators

so the Crux of it is that they should

only be using the networking tools for

job purposes I know where I where I

worked at this um ISP we all worked in

the um

the admin team we were doing the network

support for large customers and then

obviously there was a whole bunch of

teams under us here

like a HR

Finance Etc but none of these could get

out to their social media this is say

for example Facebook that was blocked

but the admin team they could obviously

decide what went in and out of the

network so they let themselves get out

on Facebook eBay whatever they wanted so

um we didn't actually have a user

agreement there we just got hired and we

started working but really the point of

a user agreement is you're not doing

things for the network or giving people

access to things that aren't really work

related

so access only areas that are under your

purview so as the administrator you may

or may not be able to configure ways of

you getting into firewalls and other

devices that you might not manage but

the agreement that you've signed should

prevent you from doing that

user accounts only changed under company

policy and with correct authorization so

this would be something like a friend of

yours that's asked to to get out on some

device or they're asking if they can and

access their emails from their home

computer these things that you might be

asked to do but you you shouldn't be

allowed to do

your password policy uh I've actually

seen a few

um News interviews especially in the

last couple of years

of people giving interviews when they're

at work and you can actually see a

Post-It note on their monitor yeah

saying what their password is

so this is obviously a big No-No some of

the things that you maybe maybe

implemented are they're no reuse or

changing the last character such as a if

your password is a b c d e f g one you

wouldn't be allowed to change it to all

be the same and then two on the end

obviously for the work Network

no writing on Post-it notes expiry

length again this is all a pain because

people are going to be forgetting their

passwords and logging tickets it just

depends how secure your environment is

upper lower case is pretty common plus

special characters and numbers

non-dictionary words so again you could

be just looking at

and people choose things they're going

to remember like um

I think there's only one Ellen Bloom but

you know what I mean balloon kite teacup

all these kind of things are they

allowed to use passive password

management software I've got password

management because I've got maybe 150

different types of software and service

I use I've managed about I've got about

14 15 websites some I'm on every day and

some I only check in once a year maybe

but I mean just to try to imagine you

can't have the same password for all of

these or you shouldn't so try to manage

them this is a bit too difficult it's a

robo form I think it's called

on off-boarding so policy for hiring

people and then terminating this should

obviously go through the HR team as well

because the chances are if it's a big

company you may not know who's coming

who's gone and and obviously sometimes

people will give notice

and they're for um privacy or whatever

other reasons uh they're not allowed to

work at the company anymore they're

basically in in the UK it's called

gardening leave they're told to leave

immediately but they're paid for the

rest of their contract

what access and privilege levels they're

given and when are they given email

access and access to Shared directories

and files are they given best practice

training this is normally

um in the form of CBT and then they get

a certificate maybe and then that goes

off to the manager for filing

just to prove they've been shown what

they should and shouldn't do do they get

a smartphone another what are they

allowed to use this Smartphone for

uh licensing use of corporate hardware

and software and I remember when I

worked at a large company I won't say uh

who they had

um they had a few servers that we could

use for internal files but people would

download it was cracked software

crack software and it was video videos

exams and a whole bunch of other stuff

that technically should have been paid

for with um hard-earned dollars but um

it was all put on there for free now

the um I'm sure the man at the top

managers didn't know but some managers

knew what was going on and this is going

to leave your your company uh legally a

light bulb download and sharing policy

training with a sign off which I've

already mentioned mentioned could be

computer-based training end of training

exam I had to do all sorts of things

health and safety and harassment

all this kind of stuff when I worked

even when I was a contractor

International export certainly in terms

of hardware and software say for example

the USA

when they developed the um GPS software

the it was only allowed a thing within

something like 100 meters accuracy the

soft the software you they could drop a

bomb then within a window of a moving

car

um but um that was not allowed out to

the public and now it's I think it's in

in the range of around 10 meters the

other thing is obviously encrypted

software is uh restricted because

depending on the level of encryption

issues by uh for terrorist organizations

so if you buy any software say for

example for from Cisco if it's a high

level encryption you'll normally need

some sort of license uh you can get it

from the government or um you know just

to do your own research and see how your

government deals with it satellite

satellite technology and images that are

protected or sensitive

uh there could be Financial penalties or

you could be criminally liable for uh

what goes on so

just be careful data loss could be

accidental or malicious I've even heard

instances of and the talk about this

elsewhere but the word computer gets

decommissioned sent off for sale in a

shop somewhere and then somebody can see

all the data I've actually on um eBay I

bought a Cisco router I'll do this image

here bought a Cisco router I booted it

up and I had a load of um IP information

password information

usernames and this was for a large ISP

um an internationally known ISP so

heaven knows who was decommissioning

their equipment but it wasn't being done

very professionally

have a policy for your clients devices

your network devices and any storage

devices and there's normally

um software that you can wipe off hard

drives or sometimes they have to be

destroyed

identify what's most sensitive normally

addresses credit card information emails

make sure people are trained and review

the training

I've talked about remote access

equipment you need to also work out who

is allowed remote access this can be

um

this could be sales if they're on the

road it could be

um

Telly see

telecomuters

that kind of thing people who work from

home

what VPN software are they allowed to

use are they allowed through SSH

software or if they don't have a good

internet connection probably people

won't use modems anymore but

uh disable HTTP access I've talked about

this elsewhere https but when you have a

device a lot of the time you can put an

IP address into a browser and manage it

what's your favorite VPN client software

what are they allowed to download if

anything onto Works laptops

are they allowed the intranet what can

they see on the internet and where can

they access it from Works emails a big

one especially with the uh the latest

presidential campaign as you know

um one of the candidates was accused of

download insensitive email onto their

from The Works servers onto their home

servers

what happens when there's an incident

there should be a policy because some

places have worked people are blaming

each other finger pointing nobody knows

who's responsible for what so there

should be

written

procedures and also training so

everybody knows who's responsible and

what the procedure is for um escalating

it who gets called who gets paged

uh who are the stakeholders so um you

know your Chief technology officer your

network manager security manager all

these kind of people who are they

involved depending on what the problem

is

so identify the start procedures the

start the procedures and the steps that

take place you're normally work in some

sort of framework like

ITIL it infrastructure Library

they have qualifications on them

procedures you should be using

who declares it's an incident uh within

ITIL you've got um

you've got different streams problem

you've got the problem manager normally

on any team that's one person who

everyone reports a problem to

instead of basically everyone in the

team being told through help desk

tickets and then they tell other people

the problem manager will receive all of

the reports of the problems and then

they will escalate it when there's a

resolution it'll go through the problem

manager and they will communicate it

through group email phone calls or

whatever

uh can their damage be isolated

um can it be who's who's in charge of

actually removing it who will they speak

to can they um who's got the authority

to um to escalate it to say

um Cisco attack or um the AWS uh Senior

Team if you've got a support contract

with Amazon

uh then eventually hopefully it's

recovered Network restored to normal

function there'll be a debrief after if

you go through the idle procedures

there's a normally a meeting a

resolution and then something will

happen to

um change the procedures so it doesn't

happen again

the training or there could be some sort

of consequence if somebody's made a

mistake that they should have known

better

BYOD bring your own device normally and

not allowed in fact most places really

should have the USB ports disabled

um and decided who can use what where

the policy per device so for example

um can they bring a whap in probably not

could they bring a USB device in

even phones are they allowed to bring

phones in could they try and pig you

back onto the wireless network all these

kind of things there should be a policy

for

and who owns what data if somebody

brings in their device and but they're

using it for work you know who entered

data this all needs to be clear what

applications can they use

and what can be taken off-site as well

you need to decide what hardware and

software can be taken off site

the acceptable use policy uh stop and

search depends where you are and how

secure the site is but people can search

your bag

uh speaking of which I already mentioned

the acceptable use policy there should

be a security policy included

how the network should and shouldn't be

used what you're allowed to do it should

be clearly spelled out and signed

websites you can access I know when I

worked at this particular ISP

at the end of every month the manager

would per employee

they would have a list of every single

website you went to and how many minutes

you spent on the website so if you've

spent 60 Minutes on whatever say eBay

even though and we couldn't do it but

say you were found to be on eBay for 60

minutes then obviously there's going to

be a consequence you'd either be told

off written or an invariable warning or

you could be sacked

and what you can and can't download a

social media again this is a killer

you're not really being paid at work to

social media unless it's part of your

job for example digital marketing NDA as

well these are these are huge in the

corporate environment

protects non-public information so

you're you're learning about customers

names phone phone details uh who are the

key contacts all of this kind of

information what are the consequences of

the breach this could be

um Criminal

or it could be civil so you could have

to pay Financial penalties

and this creates a confidential

relationship between the disclosing

party

and the receiving party

your boss or your company and you which

is fair

uh the system life cycle which is asset

disposal something is brought into

um Commission

oh sorry I did this in a weird way so

integrate devices some something is

brought into the network and then it

would have to go through a chain of

events for example a router would all

have to be cabled up then it'd be passed

on to another team to do

um username and passwords for example

then it might go to the security team

for configuration

then it might go to the backup team to

make sure that it could and they can

download files and configurations and

recover it if there's a problem

and procedure to decommission what

happens uh does it go in the bin does it

go to a shop for sale

and as I've already said and if it's

going to go for sale then all the date

all the data needs to be removed hard

drives are they going to be scrubbed are

they going to be physically destroyed in

a furnace or some other device what are

the laws for recycling a lot of

countries now are really hot on and

non-recyclable stuff so if you can't

destroy it how are you going to render

it and usable or the data on it unusable

certainly

safety procedures

um

so who can troubleshoot the equipment

people need to know what air their job

is you could um

ignore that sorry authorized Personnel

who can cable stuff who's been trained

who's insured monitors as well certainly

the old cathode ray monitors there was

the back of them and the front

uh just massive things it would take two

people to carry them and they'd have a

massive electricity electrical current

going in through them as well even when

unplugged

um it still held a massive uh current

and could have shocked somebody or

killed them

who can move what uh heavy lifting so I

work for as I said an ISP and I work for

the network support team I remotely

accessed routers and switches firewalls

load balances and one day uh one of the

one of my bosses asked you know you've

got racks these big racks that are full

of really heavy equipment and some of it

can take up a half rack a massive Cisco

switch and he came and asked me if I

could remove one of the switches and put

a new one in now I wasn't actually there

for that this is down to the hardware

team at the time this stuff weighed

something likes

um

say 150 kilos and he was asking me to

somehow pull it out

put it somewhere and um put the new one

in I wasn't actually trained to install

this heavy equipment I I didn't have any

safety equipment I couldn't move it

and um maybe he just didn't care or he

was just ignorant but I had to turn

around and say well I'm not actually

qualified to move this equipment but I

am qualified to support it but I can

only connect to it over the network

um he wasn't very happy but it's better

than me breaking my leg or whatever is

there any safety equipment required

normally when you're installing heavy

stuff you need a hard hat

so you you need your hat you need your

boots uh you've you've got to have read

the training manuals

um are you insured and there's a whole

bunch of stuff yeah normally it would go

in a trolley again who's who can use

this trolley

uh electrical circuits certainly in many

countries for example Germany and

Australia you can't even change a plug

you have to be a qualified electrician

to access electronic equipment

all right so we've covered a lot of

stuff your user agreement your password

policy and the levels of password

leaving the company so joining leaving

the company any licensing uh export for

example security images and um

all this kind of stuff what's it

protected by and what you can explore

and import what happens to prevent data

loss of remote access

what happens was that when there's an

incident can you bring your own device

hopefully not

sign in the acceptable use policy

your non-disclosure

system life cycle and then finally

keeping keeping safe

that's all for now thanks for listening

[Music]

thank you

welcome to module 14 lesson 4 securing

the wireless network

a few things we want to cover syllabus

items uh WPA WPA2 tkip rc4

ccmp AES

EAP

lots of abbreviations gfn sync

if you've been using wireless routers

for any period of time you've probably

heard of WEP which was the first

protocol used

um to secure your wireless network it

was um it's pretty much better than

nothing I guess but it was flawed very

easily crackable and quite quickly after

it came out they realized they had to

upgrade it and replace it with something

better

and then it's upgraded uh replace with a

Wi-Fi protected access as you can see

the title at the top web is a wireless

equivalent privacy I think it stands for

from 2003 WPA was available it uses as a

dynamic key management and it's based on

EAP

WPA uses temporal key Integrity protocol

so I'm glad they do abbreviate it so

you've got something like 50 trillion

key compilations which is quite a lot

you can use it with radius in the

Enterprise we've talked about radius and

radius servers elsewhere in the course

so this basically offloads all of the

management and um

and authorization onto another device

that's um designed for that purpose

he uses an encrypted hash

each packet has a unique encryption key

a WPA2 is based on the 802.11i

architecture if you want to prove that

documentation it can integrate with ATO

2.1 x there is they do allude to this I

think in these syllabus actually and

it's a method of authentication and

authorization running on their layer 2

networks it's covered in quite some

detail in the Cisco CCNA actually

this allows users and devices to

authenticate with EAP plus it uses

tacaxa radius so just take a little bit

of setting up but you'll certainly find

this in Enterprise level Networks

the rc4 was replaced by Advanced

encryption standard AES this is 256 bits

as a minimum and Beyond

a TK IP was replaced by computer mode

with Cipher block chaining ccmp

uh and I've already mentioned uses uh

encrypted hash

each packet has a unique encryption key

um again I mentioned this earlier

MAC address filtering I've just found a

basic uh router here and even this cheap

one and looks like um maybe it Linksys

one at the looking at the colors you can

use their filtering enable prevents

clients

um listed from accessing the network if

you want to stop certain clients or you

can have a permit only list whereas you

manually and decide which packets go and

which Mac addresses are allowed

uh should be used with other security

features in case of Max spoofing and

it's quite easy certainly on devices

I've managed to log in and manually

change the MAC address of your device

and here's a permit list for just a

random device a random device I found

EAP extensible Authentication Protocol

it's a framework used in wireless

networks they've got an RFC for it if

you have the time to look

100 plus types available so I think

they're only list three or four in the

syllabus

EAP md5 uses a series of challenges and

responses

TLS this was designed by Microsoft and

uses a certificate system

fast is a designed by Cisco and it uses

a TLS tunnel with a secure socket layers

and on that node it also uses shared

secret Keys these are unique to each

user and they have protected access

credentials

ttls uses the secure TLS tunnel

and then finally this is also in a new

one in the syllabus uh PE AP increases

the protection of authentications by

creating a protected TLS tunnel

and within the tunnel on Authentication

Protocol such as Ms chat version 2 can

then be used

geofencing is a feature that is actually

built inside software so you don't

actually have it running on its own it

uses GPS or radio to Define geographical

boundaries I.E who's allowed in and out

of your network or device

uh triggers this default the triggers

defined for devices entering or exiting

the network boundaries

all right so just some of the we're

basically hitting some of the syllabus

items so this is why we went through

pretty quick uh WPA tkip

ccmp EAP and GF and Tim

okay that's all for now thanks for

watching

[Music]

Network Tools hardware troubleshooting

tools

in all the previous lessons we've talked

about a lot of different things and in

the very previous lesson we talked about

network security and how important it is

so in this final lesson I want to talk

briefly about some of the network tools

that were going to be useful when we're

running a network specifically in this

module about some of the troubleshooting

tools we're going to start off by

discussing the general top topic of

Hardware diagnosis and troubleshooting

and then we're going to move on to talk

about four common tools that are used in

troubleshooting software these are the

diagnostic disk multimeter cable testers

and a postcard there are of course other

tools however these are some of the

major ones that we want to know

specifically for this network plus exam

if you recall very early we talked about

some of the cable tools as well such as

toner probes and punch down tools and

those sort of fall into here but those

are more tools that we use to create

cables rather than ones that we're going

to do troubleshooting with

so we've briefly discussed Hardware in

the past but we need to take a closer

look at it for the sake of this module

Hardware is a term that refers to the

physical components of a computer system

including hard drives power supplies RAM

and other stuff Hardware unlike software

it's not a program it can't be installed

it can however be physically placed or

installed or changed in some cases but

this generally requires taking apart the

unit and physically installing something

new on it and when we're talking about a

computer I just want to point out that a

router a switch these are types of

computers a printer they do have

Hardware inside of them so important

that we realize this term is really

all-encompassing and because Hardware is

made up of physical components it

generally takes physical tools to

troubleshoot them by saying physical

tools this means tools that physically

come into contact with the hardware in

order to test it now some of the

hardware troubleshooting tools can

actually be programs that run on the

computer and one of those I'm going to

talk about in this module

so this non-physical troubleshooting

tool is commonly called a diagnostic or

diagnosis disk this is common software

that's used to test the system's

Hardware or in some cases the router's

hardware and so on it runs a series of

tests on different pieces of the

hardware in the system and if there are

issues that need to be fixed it'll

notify you you might be thinking if the

hardware of the computer is meant

malfunctioning how can you run a disk

well as long as the system's clock

circuits disk drive and CPU are

functioning diagnostic disk can be used

so again it does require CPU

the disk drive

or the USB contact whatever it is that

is going to

contain the disk or we should say

perhaps disk in some cases

and

clock circuits

which are the circuits that allow the

CPU to run

now I just made the C right here because

a disk with a K it's like a hard disk

like USB drives flash drives a disk with

a C

is Optical

now in general these disks aren't going

to State what the problem is they're

just going to say that there is

something malfunctioning and then it's

your job to actually take that

information and relate it into something

useful

they usually do this by producing a list

of all the different Hardware components

and basically saying which of them is

malfunctioning the course of action is

then up to whomever is going to

physically make repairs or test for more

this person is usually the administrator

or an I.T consultant or specifically

someone who's been sent out by the

manufacturer there are a number of tools

that they can use to diagnose once they

know what part is malfunctioning a

multimeter is one of the most common

tools that we see in the field of

electrical work and hardware

troubleshooting

it's used to test circuits outlets and

other electrical components of most

devices now there are very different

types of multimeters out there but they

all generally test for the same thing

they measure electrical current

resistance and wattage or voltage rather

current is generally going to be

measured in watts

resistance in ohms

and voltage

in volts

in the case of a hardware

troubleshooting the voltage and

resistance functions are actually going

to matter the most

may tell us information about say the

power supply or the wall socket that's

plugging into

now the only times that you're really

going to see or use a Multimeter

to be helpful for troubleshooting is

when we're talking about power supplies

and fuses which are also related

anything that has to do directly with

the electrical on the OSI model what

we're looking at here is layer one the

physical layer

voltage tests are important because they

can see if the power supply of a

computer or device is actually receiving

power the multimeter shows there's no

voltage and the power supply is probably

malfunctioning the resistance function

is used to test fuses if the fuse is

blown or faulty needs to be replaced the

multimeter is going to tell us this by

the resistance

so this is sort of what a multimeter

looks like this one would be considered

analog because you can see right here it

has a

basically a doesn't have a digital

output it's going to measure it with

this

um arm here that will move and then you

can read it based on the numbers that

are above there are as well digital

multimeters but either way they're all

going to have two probes which are

generally black and red the black road

probe rather is usually either for the

ground or the negative

and the red just like on your car is

going to be

for positive the dial in the middle is

going to be to test to determine what

you're going to test for are you going

to test your voltage are you going to

test for ohms are you going to test for

wattage etc etc

by the way the reason it's called a

multimeter is because it has a volt

meter in it

it has a

ohm meter in it Etc

so we combine all of these into one

device which is called a multimeter this

probably looks familiar if you have

already taken the a plus exam

now out of all the hardware failures

that can happen the one that's most

common has the biggest effect on the

network is cable failure this type of

thing happens all the time and there are

tools that are created to help with this

problem

cable testers are generally hand held

devices that are meant to test cable

connectivity they test to make sure that

the data is being communicated through

these cables properly

and there are a few main types of cable

testers

continuity testers are the least

expensive kind and all they do is test

for a broken cable basically they tell

you if there is continuity in the line

data cabling testers are a bit more

expensive they can actually test broken

cables and properly Twisted cables

shorted connections and more they'll

tell you what pins within the cable

are faulty

finally there are things called time

domain reflectors or tdrs they're the

most expensive out of the three so as we

move we're going from

less

to more they test exactly where a break

or issue is and the cable can be found

so they do this by sending basically out

a signal and they wait to see how long

that signal if I have a signal

let's say we make a little chord here

and I have my time domain reflector

connected over here it's going to send a

signal out

and it's going to wait and see

how long it takes before it's reflected

back

then they convert this time into a

distance so they know how far along the

cable error was found this way they can

literally tell us where

the problem took place and help us fix

the problem at its source as opposed to

us having to sort of try to find this

blindly the last thing I want to talk

about we talked about this in a plus as

well is postcards post stands for power

on

self-test and you might remember this

from the beep that you get at the very

beginning when your computer starts up

this card is inserted into a slot of a

device and it can tell us what is not

working in the in the system by giving

us generally a sort of code called a

postcode sometimes this is a beep code

as well

generally speaking you have to relate

the code to a manual to figure out what

it's telling us

these cards are really beneficial

because they allow us to test a

non-starting system without having to

start from scratch and restore the

entire thing in other words they can

test the system that would otherwise

have to be restored to a previous

version or which we'd have to rebuild so

the cards run the tests while the system

is attempting to start up and gives us

this beep code or this error code

then we can go to the code

look at a list and determine where the

problem is for instance perhaps the ram

is bad or is not just not seated

properly or perhaps it's not able to

find its firmware

so just to recap we talked about

hardware troubleshooting again Hardware

is the hard stuff not software we

physically have to deal with it and some

of the common tools we looked at were a

diagnostic disk which generally is just

going to tell us which item

is malfunctioning

and remember a diagnostic disk is in

effect

piece of software

we also looked at a multimeter

which is for electrical things this is

going to test volts

resistance

and current

faults and resistance are perhaps the

most important ones resistance for fuses

or Breakers

Volts for power supplies

we also looked at cable testers remember

there are three different ones that we

looked at continuity testers are just

going to tell us whether or not the

cable works

cabling testers

otherwise known as data cabling testers

will tell us actually which pins aren't

working

and

time domain reflectometers

let me write that out

will tell us where

the error is occurring

finally we have our postcard remember

post stands for power on

self

test

and this is going to tell us in a

non-functioning

or non-starting system

where the error is

it's very much like a diagnostic disc

however the diagnostic disc does

require the CPU

clock

and the disk interface

is functioning the postcard it's

literally a card we insert and it'll

tell us itself it does this again by

giving us a code that we can then

reference on a list

[Music]

welcome to module 15 lesson 1A physical

testing tools just updated the uh from

the last presentation really there's a

few extra little things slipped into the

syllabus which I I think is important to

cover

the cable crimper the punch down Tool

The Wire Strippers

otdr cable certifier we may have

actually mentioned these in other areas

of the presentation but I just wanted to

specifically address each one

cable crimpa also known as a y crimp hat

you'll be familiar with this tool if

you've created your own cables a lot of

people do at home just to save money

because they're so expensive if you buy

them from the electronic shops for some

reason

and also if for any reason something

goes wrong with the end of one of your

cables you could just snip off the end

and just um create your own

a cable it's fairly easy to do well with

a little bit of practice like anything

so you'll need a cable crimpo which you

also buy from the electronic shop use to

connect the end of a cable to a

connector it can depending on which one

you buy you can actually strip the cable

you separate the wires and then you can

um insert into inside here the

connector the plastic connector pop the

ends of the cable in which you've also

stripped With a Stripper and uh and then

clamp it closed and that clamps down on

the wires in the correct door down

different types of cable crimples for

different connectors

the punch down tool is known as a chrome

tool also used to connect wires into

punch down blocks

it strips off the insulation on The Wire

before inserting it into a punch block

not something I've used before because I

didn't

um

didn't use any of the punch down blocks

uh I did some cabling but didn't use a

punch down

not something I was interested in wire

strippers used to remove electrical

insulation from my wire on this

particular figure you can see the

difference and sizes

so you choose the correct size for the

cable type and that strips out the

um housing of the wire the plastic

covering and exposes the actual cable

itself

it has a center notch

otdr this stands for optical time domain

reflectometer I'm not saying that again

used to locate faults on networking

cable

I mean there's a argument that you if

you just think there's a fault in a

cable you just swap it out anyway it'd

be cheaper but it's available tool

anyway it sends light into the fiber and

based on the quality of the reflected

light it can determine the following

thought location length of the cable

loss of signal if applicable

a cable certifier it's used to carry out

tests it can test the following

conductors in the ethernet cable

continuity in the wires proper pairing

of the wires as well it's quite handy

you just plug it in

and it will give you lots of different

reading depending on the model you have

and how much you've spent

proper termination of cat cables

so they're covered in the syllabus which

is why I give them specific slide each

instead of just mentioning them in

passing as we may have done elsewhere so

the cable crimp are the punch down Tool

The Wire Strippers otdr cable certifier

all right so that's all thanks for

watching

[Music]

thank you

welcome to module 15 a lesson 1B

software testing tools

I'm not going to cover stuff that has

already been covered unless there's a

new point

or some of the reason for doing it

uh packet sniffers

Wi-Fi analyzer bandwidth speed tester

CLI tools command line tools uh not

already covered because of the way the

syllabus is set out we have to cover

some stuff earlier in later and in the

middle because it's relevant to that

particular subject for example security

or troubleshooting

I put an image here for Wireshark

um Wireshark I'm going to say a must no

missed

now you must know sniffing and uh

Wireshark is just the industry leader

and the good news is it's free to

download you could have a virtual

Network on my Cisco virtual rack which

is free on howturnetwork.com it actually

you booted up you've got to find your

own Cisco image because Cisco don't give

them away but I wonder why sharks you

can actually see traffic live passing

between your routers and other devices

this is an essential tool and you need

to understand it for troubleshooting

so uh really important you can see all

your protocols and packets and all that

kind of stuff so

um you'd you'd normally load this uh

software

all right the Wireshark it'd be loaded

onto your laptop if you're

troubleshooting you would leave it

running say for example you'd leave it

running for an hour

and and then you could analyze the

output

and see where a particular problems

happening is it is it happening for the

the whole hour is there some sort of

um

issue spikes and then or does the issue

sort of happen over this period of time

that kind of thing so the traffic is

going into your switch from the server

and you will configure

um the switch over here you would do a

configuration command on the switch to

send the traffic out on whichever Port

you've connected your laptop to

um you've just got to be aware of I'm

just telling you this because of the

real world you've got to be aware of CPU

and you've got to make sure that you get

permission off whoever the

um person in charge is when I've worked

on network teams and

um I knew the procedures and policies

which we've already talked about what I

can and can't do but if it could be

Network effect in for example the CPU

then you've got to make sure it is done

out of hours or you've got permission

so you'll check for traffic patterns of

Base a traffic Baseline any

irregularities they will pop up

you'll be mirroring a port

just be aware the package slippers can

be used for good and bad so they cannot

also be used by hackers so whenever

possible if you're connecting over the

network use a secure shell this is a

Wireshark we and they call it captures

as well it's handy to know the uh the

vernaculars

um ethernet zero looks like the port

uh you'll you'll this is the dashboard

all around here

and in this part here you can actually

click on these uh little arrows and it

will expand so you'll see the layer one

which probably won't be of interest to

you then layer two and then you can

click on this and you will see that it's

an ARP packet you will see source

uh destination all and all this kind of

stuff and then down here is all your

ones and zeros and hex which you

probably generally won't be interested

this looks like it's uh some sort of uh

pattern over time and you can see

there's a spike here that's more on here

and here you can decide exactly what

traffic you're you're monitoring this is

SS H telnet and whatever you wanted to

Monitor and then it's a in a pie chart

here and obviously a graph form here

really handy so you can go to your

customer or your boss uh with all of the

facts and say when this happens that

happens when this happens such and such

Doesn't happen and you can prove what is

or isn't the issue on the network so um

please do check out the Wireshark

certified network analysis

um

the network associate sorry

qualifications really important we've

got it on um how to net

work.com

um I think there's maybe other people

offered the course but most people just

seem to just Skip by but this this will

be a lifesaver if you're looking at

being a network engineer

anyway Wi-Fi analyzer this is obviously

a graphical

output that has been discovered with the

piece of software it reports on your

SSID which you can see here

and Mac addresses channels use you can

see the Mac addresses of devices here

uh challenge use speed that kind of

thing

and it represents the output in the

graphical form as you can see it tells

you the security protocols and more

importantly lack of so you could um we

talked about Rogue access points and

bring your own device earlier you could

be doing this in work or you could do it

as part of a security survey

and here's another image from the same

sort of piece of software

all right bandwidth speed test damage

we've all used these because if we've

got problems with our speed at home

moving at work maybe known as throughput

testers they can be Hardware software

based it's easier for us obviously to

use the piece of software which will

send a certain amount of packets

upstream and give you a report of x

megabits per second then the downstream

then the same sort of value

so it injects traffic into the network

you could actually use this on your Lan

one or for your home broadband

connection the handy thing is you'll

normally get a graph saying um you know

how fast or slow it is

free to download if you want super duper

uh outputs and charts and that kind of

stuff it'd normally be paid

CLI this is where the rubber meets a

road and most Network Engineers kind of

worry about using these color commands

like even something simple like ipconfig

gives you all of this useful information

here that help you will help you

troubleshoot now you can use the GUI but

it's just a little bit more clunky

you've got to go through a menu to get

to another menu and then it's only going

to show you maybe 50 of what you could

actually see if you use the

um command line and if you're doing some

sort of emergency recovery you're

probably only got command line available

anyway

a typical exam question

ipconfig will give you the TCP

information on Linux devices this

ifconfig classic exam question that is

IP information for your local interfaces

including your wireless adapter any

um virtual adapters

virtual land cards Wireless

or ethernet

uh you can use switches to drill down

for example ipconfig forward slash all

there's a whole bunch of switches

actually uh most

um command line tools will let you issue

the question mark and then it will save

these year options

IP tables this is a Unix command a lot a

lot of people it's you'll either you you

use Unix a lot because it's your job or

you've probably never touched it at all

but it configures the kernel firewall

the only reason I mentioned this command

is because it's in the

the dreaded syllabus oops syllabus

so

um I think just know this command and

what it does known all this stuff I've

put it here so you can just see some of

the options but I really doubt that you

would need to know it

um I took this uh lot here from

tutorialspoint.com if you're nowhere

look at that URL

net starts a handy command basically

short for Network statistics thankfully

so it's easy to work that out shows your

active connections tells you the type of

services you're running and you could be

in for a surprise

um if you see things running on your

device that you you didn't think should

be there

there's a few switches let's start minus

n minus a minus B I'm not sure you'll

need to know the switches although I

can't guarantee it active connections

the applications the connections without

doing a DNS resolution

uh here's a net start from uh this is

from one of my authors actually I

recognize the name from his device he's

obviously named his device after himself

let's start mine is a and you can see

the state of all of these um ports

there's an established Port here

and then you could obviously do a search

and find out what this is he may what

may well be connected to a Remote device

he may be chatting on MSN or Facebook

Messenger or and you could quite easily

find out what all these ports are for

TCP dump and here's the output here

it's a Unix command it's a sniffing tool

so what you can do is use it to Snoop

um the if you're if you want to do the

snooping it's the Snoop command if

you're using Solaris

um pretty specialized a bit of software

but I've seen some of the network teams

using Evernote menu you can view the

packets on the Y app

pathping

now this is a tracer command actually

it's a TCP tool it provides information

about Network latency and sends icmp

Echo requests

and map I think I mentioned this before

actually she used to discover computers

and services on a computer network in

order to create a map

and you can see

there's a whole bunch of services here

many of them probably look familiar to

you

and at the end it says Two Hosts up and

how long it took to scan it

uh vulnerability scanning Tool uh just

bear that in mind again typical type of

question they'll ask you what's nmap

used for or

um tick the relevant vulnerability

scanning tools used for auditing by you

or obviously whatever can be used for

good can be used for bad and it can be

used by hackers

dig and he said the command has been

used here

domain information growth it basically

sends off a query to DNS servers it's

the same as the NS lookup tool but this

particular one is used for Linux devices

now you can see it's done a search for

example.com

and you can see uh the name servers here

IP address DNS servers cash timers that

kind of thing

that looks like a um that looks like

Google actually

from if my memory says I think they've

got eight eight eight and eight eight

four four you can check for yourself all

right so looked at some cool stuff uh

package sniffer Wi-Fi analyzer bandwidth

speed taster and some important command

line tools remember we're covering this

in in other presentations too so this

was just a subset of all the stuff that

you need to know

so that's the end of the presentation

thanks for watching

[Music]

thank you

welcome to module 15 lesson 2 height

availability and low balancing we're

just hitting another syllabus topic here

um just a brief overview really high

availability

[Music]

vrrp hsrp load balancing and high

availability this refers to the ability

of a user to access the service no

surprise

High availability is a common networking

term it refers to the continuous

availability of a service

for a higher period than normal now

obviously we're looking for the 99.99

percent

in order to get the highest possible

availability we usually need more than

one other thing

for example um some Cisco switches come

with

to power supplies

and even

even this has been improved upon so they

have not just the fact they've got two

power supplies but they're hot swappable

so what that means is you don't need to

reboot the switch you can pull one out

the inactive one and then slot another

one in and then you've got two active

power supply units and in case one fails

so measured as a percentage of uptime

which is five minutes a year

uh for a network to be highly

availability it should survive any kind

of failure

I'm not saying there's such a thing

doesn't exist but even the most robust

networks there was a recent outage due

to

um severe flooding in Australia I think

it was just a few months ago where it

took out Amazon uh S3

service so which you would think would

be one of the most available and secure

and robust uh hosting Platforms in the

world but even some of those customers

were taken out

so high availability can be achieved by

configuring redundant components so if

one one part of it fails the other part

takes over

now in the context of a routing we've

got protocols such as vrrp Virtual

Router redundancy protocol and hsrp

which is done by router protocol

these are what are what is known as um

High availability protocols

these enable multiple multiple routers

oral layer 3 switches in fact to act as

Virtual Router with a virtual IP address

a default gateway is configured with

this virtual IP address so one router

will be active and this handles all the

requests to the default gateway and the

other router will be a standby so the

other router actually takes over if the

main router goes down now this isn't

load balancing because um you've got one

master router and the other one is a

slave or backup depending on the

protocol you use they have different

terms so here's an image of uh the Cisco

hot standby router protocol

at the top you with the red and the blue

you got a layer 3 switch

it should be another there we go

so uh we'll see you see the host on the

bottom they both have the same default

Gateway the Gateway is 10.10.10.1 now

10.10.10.1 is configured as a virtual IP

address on the two layer three devices

on the top

these two devices are connected and they

monitor each other so if one goes down

the other one takes over you see the

priority on the right hand switch is 100

the priority on the left hand switch is

105 so it's got a higher priority so

this one in the case of hsrp will be the

primary router

uh all traffic will go via this router

until there's an issue with it if it

goes down then all traffic immediately

in a split second swaps to the standby

router which is on the rides they both

run a virtual Mac address we don't need

to worry about that because I don't

think it'd be asked but they run a

virtual Mac address so that um a layer 2

connectivity works also

I think that's all we need to know about

this diagram

load balancing is a distribution of work

across two or more resources such as

servers and networks if you have a

server overloaded with requests then we

can have several servers share the

burden of that single server in fact

even better than that you can

um it will it can work so that the load

is balanced automatically so you don't

have to wait till one server to be

overloaded the load is shared over two

or more servers

now the other thing is just going back

to that last point the servers are

acting as a single server so devices

don't realize that load balancing is

taking place the servers are acting as a

group of servers with the actual hosts

that are contacting their services on

these servers for example

um surfing a web site and doesn't don't

realize then load balancing is taking

place

so here's an image of load balancing

you've got two load balances here so one

would be

um redundant or possibly taking a part

of the load from the other one

and then we've got an array of servers

providing whichever Services they they

may be FTP or web services

so load is distributed uh across the

servers they'll all have the same IP

address

and if there's a problem with one of the

servers that will be removed from

rotation if they're not responding I

presume you'll have some sort of

reporting software that will send a

message to the administrator saying one

of the servers has been taken out of

rotation so that can be looked into

some of the benefits optimization of

resources you get faster throughput

obviously requires careful planning for

all your bandwidth efficiency

High availability which is the whole

point of the presentation so we've

looked at high availability two types of

protocols vrrp and hsrp

low balancing all right that's all for

now thanks for watching

[Music]

thank you

welcome to module 15 lesson 3 we're

looking at SNMP syslog and s-i-e-m

these are exam objectives

you could go into each of these subjects

in quite a lot of detail actually

there's the entire book so that's an MP

which um we won't we'll only be doing an

overview so you're familiar with the

the terms used we'll talk about these

services

Harrison MP Works email Cinemas SMS

alerting

syslogs and the benefits and Siem SNMP

you'll be referring to a fair amount as

a network engineer a guess I get it just

depends on your network some of the

larger networks I've worked uh on you

actually have a team that deals with any

SNMP reporting and any configurations or

perhaps as a network engineer you'd have

to enable SNMP reporting on a particular

device

do some testing to make sure that the

receiving station the network management

station can receive information which we

refer to as traps from the device and

then you will sign off that device as

compatible

so SNMP is an application layer protocol

and the idea is it Exchange Management

data between the devices on the network

or from a certain device to the network

management station

issues to Monitor and manage devices on

the network such as router switches

servers and it even drills down to

individual ports for example if you have

a switch

with 24 ports the SNMP manager depending

on the software you have some of it's

free and some of it's quite expensive

and it can drill down and show you a

pictorial view of each port on the

switch including the power and power

button and you can enable or disable and

monitor and manage individual ports so

it's very handy and very powerful

SNMP implementation consists of a

managed device

the SNMP agent

little piece of software the SNMP

manager which is normally a PC or server

that monitors the network and then

reporting is done on there pictorially

usually

the graphical user interface

the manage device on the network it

requires some kind of monitoring and it

can be

it would be your servers switches

routers firewalls that kind of thing

an example is a storage array

SNMP agent is a program that runs on the

manage device so these need to be

written

by whoever the vendor is usually so it

can comply with the RFC

the SNMP collects information from the

device and sends it to the SNMP manager

the SNMP manager is typically a computer

that has the software running for us in

mp and a lot of the time it's graphical

user interface you'll see different

images and diagrams and Reporting pie

charts and that kind of thing

this communicates with the SNMP agent

management information base we call

these mibs we don't normally say MIB

when we speak to Engineers the maybe is

a database maintained by the SNMP agent

it contains information about the

managed device which is shared by both

the SNMP agent and the manager

so SNMP is typically enabled when you

have a storage system

again it depends on your setup

whenever whenever a specific event

occurs in the storage system this is an

MP agent running on it will notify the

manager and it sends a message now what

happens after that depends on how you've

configured it it could trigger a number

of events

or just be stored so you can see the

act I will act now by the SNMP manager

what actually happens

the Trap is in the is an event that's

reported the SNMP manager will receive

the event and take action type of

actions could be

um an email you can configure it to send

an SMS to the network engineer or a

number of people

you can even have um

an automatic um

phone number dialed or number of numbers

dialed voice message is sent it just

depends on how you how you configure it

and how important this particular

message is

quote from Wikipedia

SNMP agent receives requests on UDP Port

161

it can send requests from any available

Source port to port 161. the age of

response is generally set back send back

to the source port on the manager the

manager receives notifications these are

known as traps and inform requests

there's other types of messages these

are on Port 162. so basically UDP ports

161 and 162 is used by SNMP

moving on to a syslog which has got

quite a lot of prominence in the Cisco

CCNA exams

it's a protocol for exchanging log

messages so syslog generally sits on a

syslog server although you can configure

it a router to be a syslog server the

general rule is leave these devices like

a router to do the main job it's

designed for

instead of um using it to allocate DHCP

addresses and record syslog messages

although it can do these and a lot more

things

it can be used by devices on the network

to move all the audit logs to a central

login server again this is called the

syslog server

why would you do it it allows the

consolidation of audit logs from

multiple devices to a single place

basically it's for to give you usable

information and data you can have

different levels of syslog messaging

from urgent messages to just general

reporting and how and what it actually

does is down to you to configure

depending on your particular needs on

the network

okay lastly s-i-e-m security information

and event manager

it's a set of software products and

services that are used to monitor a

network

what it gives you is a real-time output

of security alerts generated by Network

and network Hardware so it's definitely

got a security bias

It's a combination of sem security event

manager and Sim security information

management

the security event management deals with

the real-time monitoring and

notification of security events

the Sim deals with the collection of the

log files into a central Repository

a lot of the time as with other

protocols like this you would have a

graphical analysis giving you some sort

of meaningful data that you can

interpret

the Siem Solutions are used to log

security data and generate reports a lot

of the time for compliance and security

compliance is a whole

new and expanded area

a lot of the time for you to comply with

and National standards and requirements

for security

one example is checkpoint event here

which you can Google and look at some

more information if you want to do some

research but that's um for now summary

is SNMP components manage devices and

agents and managers

mibs we've talked about how SNMP works

alerting syslog

and why we use this log and Siem okay

that's all for now thanks for watching

[Music]

thank you

welcome to module 16 lesson one web

services

this would obviously uh be a massive

area we're just touching on the things

that are covered in the syllabus what

are web services XML

programming languages and web services

their components used by web services

how are web service works

I think uh this has probably been put in

in as much as you probably you may be

asked to do some sort of troubleshooting

not uh in the respective web programming

but perhaps accessor through the network

or firewalls or some sort of

troubleshooting so you may need to

communicate with the web programmers at

some point

what are they there's a whole bunch of

applications that use Open Standards

such as Excel

soap wsdl

uddi

uses they used to exchange data between

the web-based applications over an IP

network and this is just a massively

expanded area and always has been since

HTTP was first used to display web pages

it's been improved upon over and over

again to deal with them issues speed

security

usability mobile devices it's just never

ending

so in a web service we already know the

HTTP is used to transfer

um machine readable formats such as the

following XML Json

and Jason when different software

Services onto stage dates with each

other a web service allows them to do

this over the internet

software application that requests the

data is called a service and you can

tweak these way in most of your browsers

such as their Google Chrome or Firefox

they normally have ways you can manage

extensions or um the back end

to a grade to a lesser extent

software application that serves the

data is called a service provider

and web services are a means of um

interoperating between different

software systems

the software applications develop using

a whole variety of programmer languages

and normally you'll have somebody

specializes in one or more and you can

see a few in the Fig there some have

been depreciated such as Flash and due

to security issues

season for applications want to exchange

data they should be able to communicate

with each other this may possibly be

where you have become involved as the

network engineer

data exchange shouldn't depend on any

particular programming language

so there's a need for a common language

that allow different software

applications to send and receive data

over the web

most types of software can interpret

what's known as XML tags

this stands for extensible Market

bandwidge which you can learn if you so

choose

it's a standard language for web-based

applications to communicate with one

another

the exchange of data happens through XML

files

XML is a markup language it defines a

set of rules for encoding documents in a

format that we can read as humans

generally you need to be a programmer to

understand what they mean but it could

also be read by the machines

so here's an example of an XML file you

can see it's marked as XML at the top

the version and then there's various

um prompts within the greater than and

less than markers and also the actual

text in between Network 100 status pass

subject Hardware Mach 100

so you've seen an example easy to read

it once obviously once you've learned

what it all means and how it works but

it's also easy for the machine to read

also

allows you to see what's been sent

between the web-based applications

web services web applications can send

data using the XML format they can also

retrieve data from an XML file

a standard web service uses the

following components soap

this stands for a simple object access

protocol

this is actually used to transfer the

data

uddi stands for Universal description

Discovery and integration

directory that defines which Software

System should be contacted for which

type of data

wsdl stands for web services description

language

used for describing the services

available

how are web service works it uses XML to

tag the data soap to transfer the data

and then wsdl to describe the

availability of a service it's worth

writing this out if you haven't already

if you're not making notes so you

understand which

um part performs which service because

this is the most likely thing you're

going to be asked a question about

so we've looked briefly at web services

XML programming languages and web

services

components how web service works that's

all for now thanks for listening

[Music]

welcome to module 16 lesson 2 unified

communication

just call this UC usually to save a lot

of breath as with everything

uh different media the same

communication we look at and presence

this is a real snapshot of a pretty huge

subject area so as with a lot of network

plus stuff especially the new stuff in

the syllabus you just expect it to have

an awareness of it

you see is the integration of a whole

bunch of communication

methods including voice video and data

all goes into your IP network which is

kind of tied in with the cloud now and

how everything would be you'd expect

everything to be working over IP

and over multiple devices depending on

where you are and how you want things to

work

the idea is it simplifies real-time

Communications at an Enterprise level

including it can work it doesn't have to

be Enterprise by the way it can be any

small Network including homes

making calls instant messages having a

video or audio conference sharing your

desktop with whoever needs to log in and

troubleshoot

presence information

so you see it's all forms of

communications are exchanged over IP

integrates real-time Communications with

non-real time such as accessing your

voicemail if you're not available

accessing your email text messages

faxes I don't even know who uses those

now

it allows you to send messages on one

medium but receive a response to another

an example is when you send somebody a

voicemail you've probably had this

happen before or you've left a voicemail

and it says it will send the user a text

or email

you can retrieve

um check and retrieve emails or

voicemails using any Communications at

any time

our presence is a component of UC shows

the present status of a user in real

time whether they are available and

available where they are located if if

you've enabled geoip tracking

or Geo tracking sorry

allows users to communicate seamlessly

even if they're in different locations

you can look at a person by accessing an

interactive directory and engaging

communication through text voice or

video

so that's the summary of what we've

covered just wanted to go and show you

just for more

context really Cisco's unified

Communications

I'm just going to play a video this

video is copyright Cisco system so if

you want to learn more

um all you do is go to Cisco or in fact

type Cisco unified Communications

I'll just put a video on now

foreign

[Music]

thank you

welcome to module 17 lesson one

introduction to virtualization this is

one of the few new topics that have been

added to the syllabus

surrounding virtualization and cloud

computing

and come to your offer a cloud

certification actually there's a cloud

Essentials and I think there might be a

cloud Plus

definitely a cloud Essentials because we

host uh host that course

all right module objective is the

definition of virtualization what is a

virtual machine and the software

I'm sure you've heard of it actually

it's the new or one of the very new and

exciting emerging Technologies that's

made alive a lot easier for Network

engineers

um companies from a financial and

operations standpoint and also home

users who can do a lot more interesting

things on their

um systems at home

so it refers to the technologies that

allow a single physical computer or or

server obviously environment to operate

as multiple virtual machines

simultaneously transforms the physical

Hardware resources into virtual Hardware

resources

so what you normally have one device

running one operating system you can

have depending on how much Hardware you

have and how you apportion it and two or

more virtual machines

a virtual machine is an isolated

software replica of the original

computer so for all intents and purposes

it appears as a machine in its own right

with all processor instructions and

system resources

so you'll often see an image like this

where you have a physical computer or

server and inside and it will represent

a number of virtual machines

much in the same way as their vlans they

operate in their own right

as if they're an actual machine

a virtual machines are completely

separate and independent

by running good operating system in each

one it becomes possible to run several

guest operating systems at the same time

so you could have

um a Microsoft Linux and other operating

systems running on the same physical

device but different virtual devices

a whole bunch of virtualization software

around some free some um you have to pay

for and you get different levels of

um

software up to Enterprise and obviously

support contracts

the software transforms the hardware of

the computer including the CPU memory

Network adapting to Virtual resources

these are shared amongst virtual

machines

it basically provides a layer of layer

of abstraction so for all intents and

purposes there's a divide a virtual

divide between all of these different

machines

the labor of abstraction is basically

there to hide what's happening

underneath what you can see

foreign

as a result the abstraction provided by

the software the guest operating systems

are not tied to the underlying physical

Hardware so this is how we can actually

get it all to run

so you have a portability of moving

virtual machines from one physical

computer to another physical computer if

you so wish great if you want to do

testing interoperability stress testing

or just practicing even if you want to

do some install various operating

systems onto one device in order to

practice free exams or job interviews

so this is just an overview we've got

more to cover in the following

presentations what is virtualization the

virtual machine the software that's all

for now thanks for watching

[Music]

welcome to module 17 lesson 2

virtualization components and

software-defined networking or sdn

for short

looking at virtual networking virtual

network adapters a virtual switch

Virtual Router

Virtual Router via vrrp

the virtual firewall and sdn

and while we why would want to use sdn

so a virtual network is a system in

which the following is true you've got

two or more virtual machines connected

logically to one another they could each

just send received data as if they were

operating as physical devices

I've got an example here esxi which is

software available from VMware I think

they do offer some free software I

haven't checked as to which

um is free for home use or commercial

use and I recommend you check out the

VMware certifications on

howturnetwork.com

they're very relevant for modern day

networking

so they can send to receive data from

each other the virtual network adapter

is a software implementation of a

physical network adapter which I'm sure

comes as no surprise

so you have a physical adapter but the

virtual one is acting in exactly the

same mother and same manner sorry

and you've got a diagram here of a

physical network card

um and then you're working as a subset

of this is your virtual machine they're

running virtual network cards and

virtual machines on top of that

the virtual network card interface is a

virtual machine to the network they can

have one or more virtual Nic next or

v-nix

eat such Phoenix has its own Mac address

it needs to follow the same rules as

physical networking so it'll need to

have a unique Mac

a virtual network card in a um virtual

machine you still have to configure it

all the same rules apply it's just the

fact that it isn't operating uh

physically

so you can go and see and physically

plug and unplug cables

virtual switch or v-switch is a software

version of a physical switch it's got

Network ports similar to the RJ45

connectors you have and one

1016 virtual ports this all depends on

your software and Hardware platform

you're putting it on there's a limit of

4088 ports on all virtual switches on

the VMware esxi host

different vendors May well have

different um capabilities and rules to

follow

a virtual send switch can send Network

traffic between virtual machines on the

same host or from virtual machines to an

external network that's outside the

virtual virtualized hosts you can go to

YouTube and check on videos on how to

check a virtual air device to a live

Network and a lot of the time you do it

for home use to overcome

um limitations when you're trying to get

different bits of software and Hardware

to work for certification exams it's

quite common

virtual switch joins the network with a

physical Network when it when it

connects to a physical switch using um

physical network adapters

uh you can also get virtual routers a

software version of a physical router

obviously performs your layer 3 packet

forward in between

your subnets or lands and um vlans

obviously you need layer three

capability of some sort a virtual router

via vrrp which we covered that protocol

earlier

uh it's a virtual route is implemented

when you use vrp to provide redundancy

of the default gateway so all the hosts

still have IP connectivity

it's back by two or more physical

routers depending on the protocol you

can have two or three

I'm not sure what the limit is actually

depends on the protocol and it does

change

uh why use a Virtual Router provides the

same routing function functionality but

it's virtual so you've got all the

advantages of costs

uh virtual firewalls they're mentioned

again in the Cisco syllabus probably

definitely the CCNA routing briefly but

I would imagine in the CCNA Security in

a lot more detail

so it's a virtual version of an actual

firewall

so they're implemented as a follower

within a virtual machine or as an

appliance it provides security to your

virtual environment

does exactly the same job as a hardware

firewall

just moving on to sdn now it's um

a big topic and it's been introduced

into the new Cisco CCNA exam and I would

imagine

um

it's going to have more and more

prominence over the years to come

because Cisco have invested heavily in

sdn and there's a lot of um some Open

Standards that have had a huge uptake as

well

it provides um a high level

Administration capability to network

admins it allows you to manage your

entire network through a user interface

that abstracts a com complexity so you

wouldn't necessarily need to understand

all the underlying commands that have

been executed and how it all works

um just to manage it if you're using sdn

obviously it helps if you to be a

network engineer that you actually

understand what's happening

but um now I suppose it's like managing

your car

they've got all these different settings

on the onboard computers that change

your handling and your engine

performance and all that kind of thing

you can turn different controls on or

off like traction control and you don't

necessarily need to worry about how it

all works

all right sdns are used to control the

operation and network devices

um look into more I think Cisco I'm not

sure which CCNA version maybe data

center that looks interesting any more

details but there's a whole bunch of um

controls and formats that have to manage

your

um interface between your network the

user and all of your devices and apis to

name one

so examples of sdns or Cisco open

network environments

nikira's Network virtualization platform

why bother it basically makes your life

a lot easier as the network

administrator you can interact with your

entire network without having to

actually connect via telnet or

physically connect to your devices or

even understand all of the different

commands so if you're using

Juniper Hardware it's got one type of

um

command line interface for um copyright

reasons your Huawei and Cisco all got

different command lines different

commands all to achieve the same thing

so you don't you don't need to worry

about that if you're using SDM

so get get rid of the command line some

of the benefits again the graphical user

interface provides information about

what's going on with your network

it allows you to specify changes and

behind the scenes the actual

configurations are done with the

interface one of the apis between the

software and the hardware

all right so it's just an overview

looked at virtual networking the virtual

adapters virtual switches and routers

the RRP

firewalls and software-defined

networking and why why would we be

interested in using it

so that's all thanks for watching

[Music]

welcome to module 17 lesson 3 the

storage area network

I think come to your actually have a

qualification uh storage area networking

engineer Plus

and we actually have um such a course on

howturnetwork.com this is just an

overview touching on some of the

subjects they mentioned in the exam

syllabus

looking at storage area networks direct

attached storage network attached

storage

sanvi Das

Sun media

fiber channel

iSCSI San

Jose architecture and components of

voice guzzy also jumbo frames

Sun as we already know stands for

storage area network it's a high speed

Network the idea is it allows

um transfer between the computer systems

and the storage devices it's optimized

for this type of Technology as well

we'll see this as we go along

and here's an example which will um

you'll see in a few slides

so why bother at all why do we need a

storage area network again everything

covered really in the network plus was

created in order to solve some specific

or general networking problem

it's the evolution in data storage

technology and we'll look at some Legacy

ideas in a moment

so um unfortunately this I'll put the

wrong order here so the lines are

appearing in the wrong order there's

been progress in the data storage

technology from Das to Sam direct

attached storage is the traditional

way and it's I'm sure many companies

still use it those who don't use uh San

as a solution for storage

so a traditional client server systems

each sort of server having its own

storage and the storage is directly

attached to the server internally

usually or it could be external

search

a technology is referred to as direct

attached storage or Das

so there obviously has to be advantages

it's high speed and it's exclusive

access to the storage so it's not shared

preferred by small companies just

cheaper to implement easier to implement

easier to um

troubleshoot maintain

obviously there are disadvantages which

is why it's been

um

superseded by many companies so what you

get is a pocket of isolated storage it's

not officially utilized and this ties

into virtualization really where you

we've got this whole amount of resources

but we may only be using a certain

percentage of it which is a waste

so for example when one server has

plenty of C uh free storage and the

other one has almost ran out of space

then we've got a disparity

this is where um Network attaches

storage will help direct attached

storage design doesn't allow the free

capacity of the servers to be shared

so when a business deploys more servers

in the network the following occurs

there's an increase in the wastage

increase in the complexity of managing

all of these isolated storage because

usually you've got raid so you've got to

insert and pull out various disks

and network attached storage another

image there it decouples the storage

from the servers so the servers are

still there but we um remove the storage

as another feature makes the storage a

centralized pool of shed devices that

can be accessed by all the servers

connected to the network

now network attached storage is not a

network in its own right but a storage

array hooked up to an existing Network

here's an example of a Nas server

that's a Netgear by looks of it it can

provide centralized

um shared stories of terabytes of

storage you get enough servers for home

users as well wherever everyone can

connect to this particular device and

hopefully that device then in turn backs

up somewhere over to the cloud or

somewhere like that disadvantage is

doesn't provide the high speed data

protection needed in Enterprise

environments because it typically sits

on an existing shed corporate Network

um complete data backup takes a lot of

time and obviously takes up a lot of

bandwidth

so sun is a dedicated Network that

transfers blocks of data at a high speed

to a storage device

a low latency for the input output

request to the storage device

uh what you what sound gives you is

access to several servers that connect

to several several storage devices you

can see we've got a in this instance

we've got a full mesh connection between

the servers the switches and the storage

array there

also allows the storage devices to

communicate with each other

limitations going back to direct access

storage

this is the challenge we have with the

traditional server attached storage you

can't satisfy the ever crease in demands

for storage and we obviously have more

and more complex information

including video and voice

not scalable due to the restrictions and

how many devices you can add physically

to

um servers sun is scalable so you can

add a lot of new devices and and without

having to add new servers

you can aggregate the devices into a

central pool that can be accessed by the

servers

the server attached storage doesn't

provide High availability because if a

server goes down then you lose the data

since the data is tied to the server

so obviously

um overcomes this problem because you

remove the storage from the servers if a

server goes down in the topology then

the data is still accessible so you've

removed that as a point of failure

and though the sun connects multitude of

servers and storage devices the

performance doesn't so far because the

network is characterized by high speed

and low latency you've got the best of

two different worlds there

the high speed data transfer the low

latency can be compared to the high

performance of storage directly attached

to a server

so your storage area network is a

dedicated Network it's scalable and

highly available as we've already said

primary purpose is providing the high

speed

and the low latency

Sun media it's the actual cables and

physical wiring

It's associated with the unique protocol

and is always managed by that protocol

the protocol is responsible for the

format and sequence of data exchange on

the storage area network now you're

almost always going to have

um fiber channel

and because of the speed requirements

different types of optical electrical

transmission meter that you cannot

follow that and you can have copper the

fibers of preferred connection type

uh the sounds are typically typically

built using fiber channel

uh the standards you define a high-speed

Network that transfer dates at around

two gigs per second

the standards also define the properties

of the media and how data is transmitted

which I mentioned earlier

fiber channel is a de facto standard

the storage area network using is built

using fiber channel technology is called

the fiber channel or FC San

uh the whole idea is to increase access

to all the data and since organizations

have a heterogeneous combination of

operating systems fiber channel was

um designed to cater for all of these

different applications and operating

systems

the fiber channels solve the fundamental

problem of reliably making terabytes of

information available to hundreds of

servers more than likely at the same

time as well so serving multiple

requests

uh while direct attached storage and

network attached storage may be

appropriate for small networks the fiber

channel San is used generally for large

storage networks and Enterprise Networks

um con the concept of sand isn't tied to

any particular technology or vendor so

it can be used by a multitude it can

also be built using other Technologies

such

um as Internet Security or iSCSI

is a storage area network implemented

over an IP and it uses the iSCSI

protocol

it's a mapping of the scuzzy protocol

over TCP not sure if there's an RFC for

this actually but you can Google the ice

cozy for yourself and see um where the

proposal started

carries Block Level data over the IP

network and block storage can be

accessed over the network as if it was

directly attached to the server

is because the architecture is based on

the client server model of scuzzy

it's because the parlance is referred to

as the initiator target model which may

be you may expect a question on

something along those lines for the exam

the iscosity sign consists of three

components

initiator the Target and the IP network

the initiators the system that first

initiates a read or write request over

the IP network

example of a device is the server

Target system is the system that

responds to the requests

so an example is the storage array

initiates initiators and targets need

the physical is because the interface to

connect to the IP network

the Isis interface is available as a PCI

expansion card or it can actually be

built into the motherboard again you

need to speak to the vendor and look at

your particular specifications and

requirements

jumbo frames you may heard of before in

network parlance

it's an Ethernet frame it's got a

payload greater than 1500 bytes and it

can carry a payload payload of up to

9000 bytes

so on the contrary an Ethernet standard

frame a standard ethernet frame sorry

can carry a payload of 1500 bytes

the payload or the size of the largest

data that an Ethernet frame can carry is

referred to as the MTU and if you ever

use a package sniffer you'll see you

should see for ethernet and MTU field

the maximum transmission unit

since jumbo frames have larger mtus they

can carry more data

each transmitted frame and a network

requires a network hardware and software

to process it so we have the more frames

we have the more CPU Cycles are required

to process them

so if we use jumbo frames it only

requires a few we require less frames

because of the bigger MTU size as a

result we get less CPU utilization but

we get the bonus of increased throughput

uh we can use jumbo frames when fiber

channel frames are to be transmitted

over the ethernet

the size of the fiber channel frames are

over 2K so it becomes necessary through

the adapters and switches to support

baby jumbo frames in order to prevent

the segmentation I think we covered

segmentation early it's when the frame

is chopped up into different pieces

numbered and then transmitted and each

frame has to

um has to have an acknowledgments so

you've got a lot of overhead associated

all right so we've looked in brief at

storage area networks direct attached

storage Nas

uh Sun versus Das Sun media

fiber channel and iscs architecture and

Sam

the components of Isco Z and jumbo

frames

thanks for watching

[Music]

welcome to module 17 lesson 4 Cloud

Concepts I've mentioned earlier well

worth doing the CompTIA Cloud Essentials

exam because uh cloud computing is just

one of the core subjects that you need

to understand as a network engineer

among us a few others including routing

virtualization

um

probably Amazon storage

uh routing and switching for example the

CCNA IPv6

so this is just a real uh brief taster

looking at cloud computing

characteristics on-demand self-service

broad network access resource pooling

elasticity measured service software as

a service platform as a service

infrastructure as a service

and then private community and public

clouds on hybrid clouds

so best thing is to start with the

definition so we can kind of have an

agreed kicking off point of what cloud

computing actually is

now cloud computing from the definition

is a model for enabling ubiquitous

convenient on-demand network access to a

shared pool of configurable computing

resources examples are network servers

storage application and services that

can be rapidly provisioned and released

with minimal management effort or

service provider interaction we've all

used the cloud already if you've used

any storage for example Dropbox

box.com I think the call for storage any

Google services for example Gmail or

Google documents and things like that

there's many many others

and are all based on the cloud

so some characteristics that you need to

remember these so make sure you note

them down there's five characteristics

of cloud computing on demand

self-service broader network access

we'll go into all of these in more

detail resource pooling rapid elastis

elasticity

a measured service

so on demand basically means the user

can provision resources as and when

they're needed without getting any human

assistance so you if you needed more

memory you wouldn't have to log a ticket

and you wouldn't have to have an

engineer somewhere

turn off the server or whatever the

device is adds more physical memory

reboot it and then answer the ticket as

you may well have had to do in the not

too distance past you click a button and

more is available

we can do when consumers provision the

resources based on their needs those

resources are automatically allocated

from a shared pool

and their schedules provided by the

cloud service provider

broad network access means that when the

consumers have provisioned the resources

they can access these from a number of

devices workstations laptops tablets and

mobile devices and mobile phones

resource pooling and the service

providers resources are shared and when

the consumers on a multi-tenant Model

where consumers get a dynamic allocation

resources based upon their needs

so sometimes consumers may need more

Computer Resources and other times they

need need less so it has to adapt for

this particular requirement it's

um

resource allocation based upon demand

rapid elasticity I can't say that word

elasticity

foreign

now a consumer can be allocated more res

me more more resources if needed at the

same time if for any reason they need

less because the more you the more you

need the more you pay obviously if you

need less then they can be downsized to

provide whatever model you need the

resources you need

so it appears to the consumer that there

there's an actual unlimited amount of

resources for them at any given time

elasticity provides a lot of savings

because it's not possible when you have

a traditional data center that you've

built and you own you can't grow it and

shrink it as and when needed

obviously is measured just like a meter

so you're charged based upon your

um a number of things such as

um memory you need uh storage and uh

bandwidth

so you get what you pay for which you've

already said is um uh tracked normally

you can log in and you can track your

use of resources in real time as well as

historical data looking at

um how much you've used and the

projected requirements based on previous

usage and you can see how much you're

going to have to pay how much you paid

in the past

there's three service models you need to

be familiar with software as a service

platform as a service infrastructure as

a service

providers provide the services to

Consumers based on these three service

models so SAS swas or SAS

consumers can use the service provider

software applications and databases over

a network without the need to install

any software except for a web browser

you need to access

these uh software applications databases

run on the cloud so imagine you're

trying to program

um some application for example or just

use a huge amount of resources or

develop a program you can use the

provider's resources and scale it as and

when needed

it's provided as a shared Computing

resource to the consumers

it's essentially the aggregation of

hardware and software

used to support the cloud services a few

examples you can see there are Twitter

and Facebook there's a whole bunch of

others you can look into if you wish

though in the SAS model consumers access

the shared applications over a network

from various client devices

it doesn't give you the ability to

control and manage in the manage the

underlying Cloud infrastructure so you

can't manage the operating system

servers the network or storage and you

don't you don't want to anywhere you

just want to um use it as is

platform as a service there's an example

there Windows Azure which you could look

into in your own time in the platform as

a service model consumers have the

ability to develop and deploy software

applications on the service providers

Cloud infrastructure

uh the service provider typically

provides a competing platform comprised

of the operating system and the

application development environment

this includes programming languages

libraries tools databases and web

servers I recommend you look at the

Amazon

AWS qualifications for more information

on these

in the paas model

consumers can develop and deploy

software without the need to maintain

the operating system so you can imagine

how convenient this is to fire up an

instance for example if you logged into

the Amazon or the Google cloud and start

doing your developing it's just so easy

and quick

consumers have control over the deployed

software application and the

configuration settings

and it doesn't give you to again

manage the controller manager underlying

infrastructure

infrastructure as a service one example

is Amazon ec2 web services

here consumers access a dedicated

physical or in most cases a virtual

machine running on the service providers

Cloud infrastructure

a lot of people use this for web hosting

especially WordPress is quite easy to

fire up an instance and get it all

working

virtual machine typically comes with a

server operating system consumers

complete complete control over the OS

and can control the updates

um you have control over the operating

system application storage you have

limited control over the selected

networking components such as the

firewall that's protecting your

particular virtual device

again you can't control the underlying

Cloud infrastructure probably

um neither would you want to

infrastructure as a service you've got

four models to choose from for iaas

you've got the private Cloud the

community Cloud public and hybrid

for private Cloud the cloud

infrastructure is provisioned

exclusively for a single organization

so you get exclusive use of this you've

probably hired a company

to create all of the infrastructure for

you and nobody else can have access to

it and all of your offices and remote

offices will have access

owned operated and managed by the

organization itself

very third party or a combination

a physical location could be within your

premises or it could be located

Elsewhere on the cloud

Community it's um Provisions for a

specific community of consumers from

organizations that share common concerns

such as security compliance

jurisdiction and so on for example would

be law reinforcement

in this model the cloud infrastructure

may be owned operated by one or more

organizations by a third party or you

could have a combination

the physical location and may be within

your premises or it could be located

elsewhere

in public Cloud it's provision for the

general public so it can be used by the

general public over a network such as

the internet

um the cloud infrastructure could be

managed by the government businesses

Academia or a combination

foreign physical location is within the

premise of the service provider now a

hybrid is a mixture of any of these

separate entities but are integrated

into the benefits for the um of the

multiple deployed models

example is when the it organization uses

a public card as a temporary solution to

meet um an excess capacity demand that

can't be met by their private setup

so I've looked at quite a few things

here you need to make some notes

obviously because there's a few things

to remember for the exam

service models software as a service

platform infrastructure private

community and public cloud and hybrid

okay that's all for now thanks for

watching

[Music]

welcome to module 18 lesson one physical

security controls I'm going to whisk

through this pretty quickly because most

of it is pretty self-explanatory

and Common Sense really physical

security man traps Network closets video

monitoring door access controls

proximity readers biometrics

Cipher locks and a security guard

so the physical security control is the

measures we take from physical threats

basically people trying to get into our

data center

I guess Ram radio might be included

because I've never heard of that but uh

yeah physical security

examples I've already mentioned the man

traps the network closets

they reduce the risk of damage or loss

by preventing or slowing down physical

attack I've actually been a worked uh or

been to a few networks Consulting where

they don't have any security whatsoever

everything's shoved in a Cupboard and

the entire company website the

financials the accounting all stuck on

the server hanging off a cable in a

Cupboard and I'm sure you've seen the

pictures or may have seen it yourself

for real

and it's pretty easy to do it doesn't

have to be expensive a man trap I've

experienced in a internet service

provider that used to host some of my

equipment

basically it's a space it's a door

um within a door so you go through one

set of doors which it normally has got

some type of security keypads or

whatever and then you've got a second

set of doors you have to go through if

it's a manual Man Trap or security guard

locks and unlocks each doors and

sequence if it's automatic the doors are

only opened after getting an

identification from the person

uh the one I went to you had to do a

keypad to get through the front door and

then actually pick up a phone and speak

to the on-call engineer to get through

the second door

and it all had to be done by appointment

our Network closet is is a room where

Network hardware switches switches and

routers are installed physical access to

the closet is normally restricted by

having some sort of security control

videos

um normally record who comes in who goes

out who accesses what and where and it's

recorded for a set period of time this

can be CCTV or video over IP

foreign

electronic system I'm sure you've used

these in a lot of different places to

get in and out of different rooms and

buildings and floors and use a granted

access door if the door is open for a

predetermined amount of time and the

entry is recorded the door remains

closed when the users denied access that

attempt is still recorded

if the doors held open for too long then

it should trigger some sort of action or

alarm

proximity reader is basically electronic

access where you have some sort of smart

card and you swipe your way in and

possibly out again as well you'll

normally hold the card on or in the

reader

proximity read normally bleeps or beeps

when it has red your smart card if it

doesn't read it you may hear a different

type of beep and you may have to go and

get your car checked or renewed

when the user's granted access to the

door will open otherwise it remains

closed

it's pretty obvious to be honest

Biometrics refers to remetrics related

to human characteristics fingerprint

face Iris retina and so on and so forth

if you've seen it if you've watched any

of the um Mission Impossible movies

uh since Biometrics are unique to

individuals they're used to verify the

identity of an individual before

granting access the biometric locks

Grant access only if the biometric

feature is validated for example

scanning your fingerprint

keypad and Cipher locks the cipher lock

uses a keypad in place of a keyhole

use us to provide the correct numerical

pin code by pressing buttons on the

keypad cypherlock could have four or

five push button combination in order to

get in

uh Cipher code is created at the initial

setup but obviously can be changed

usually changed every week or every

month

and the security guard is the whoever's

been

uh got on the course got qualified and

um it has become the security person it

has a legal or inappropriate actions

all right so covered some

following items all fairly obvious I

think just to make a few notes for the

exam and I'll see you on the next

presentation thanks for watching

[Music]

welcome to module 18 lesson 2 basic

forensic Concepts

this is one of the new additions to the

network plus syllabus and it's basically

because of the increased scope for

Network engineers

and the more formal proceedings we have

in um respective Cube and computer

forensics

so this is quite um

an emerging field of

um law

and evidence and obviously we've got uh

forensic investigations going on now in

terms of um terrorism and other

threats and crimes and um we need to be

familiar with some of the basics

so what are forensics and computer

forensics the First Responders job

electronic discovery

chain of custody

legal holds securing the crime scene

high level View

some steps in basic forensic process

including collection examination

analysis and Reporting

so what is forensics or what are

forensics is the scientific methods and

techniques for collecting analyzing and

preserving evidence that's the

definition

can be used in the court of law and if

anything's going to be used in a quarter

law it normally has to follow a certain

amount of um procedures in order to

qualify as evidence as we'll see

the um computer forensics U.S government

organization states are following

computer forensics is defined as the

discipline that combines elements of law

on computer science to collect and

analyze data from computer systems

networks Wireless comms and storage

devices in a way that's admissible as

evidence in accord to law

and it all hinges on that last sentence

really it has to be admissible and we'll

go into the chain custody in a bit this

uh when I worked in the police it

applied to physical evidence in as much

as we had to know

who first sees the evidence who do they

hand it to who examined it after that

and so on and we have to have this

continuity

and it's the same in regards of computer

forensics

computer forensics help organizations

deal with security incidents that have

an adverse impact on their business so

it could be for internal investigations

also

security incidents are events that

violate the security policies of the

organization so obviously some things

may not be a crime however sharing

sensitive information as regards of your

company or take over bids or other

information about people at work there

can be a breach even though it hasn't um

it isn't officially a crime for whatever

reason

here's a screen grab if you search for

um computer forensic certifications the

website Tom's it pro has listed what uh

for 2017 are the top five

uh computer forensic qualifications the

certified computer examiner in case

which is a um vendor specific the other

ones are vendor neutral I think

certified forensic computer examiner

um

gcfa and gcfe

I'm not sure that stands for cyber

security forensics so um if you're

interested in this particular field then

there's certainly other certifications

you can follow

uh just do some research and see what uh

the employment prospects are

so examples of security incidents

include unauthorized access to data

attacks through malware or denial of

service

it's important to understand the

technical and legal aspects in order to

gather information because you could be

will cover first responder in a bit but

you that could be you

could be contacted by a law enforcement

agency told us some sort of um data or

even their Hardware that's been involved

in the commission of a crime and be

asked to take certain steps or be served

with the legal notice for criminal or

civil court

the risk is if you don't have these

forensic processes you could lose your

um evidence or it could become

inadmissible which can be quite

embarrassing because

um it could I mean the cases last

the security professional needs to know

the legal aspects

so U.S law mandates proper authorization

must be acquired before Security

Professionals can monitor and gather

information so it depends what it is

you'd be certain sort of court order or

warrant

and in the form of a paperwork in order

to um take certain action or preserve a

certain amount of evidence or hand it

over

uh organization should have a computer

forensic competence established as part

of its security policy and you may need

to have it in respect of having audits

for compliance or certification to work

with certain vendors or government

departments

so the first responder is a person first

to be present on the scene after the

occurrence of a security incident which

if you're the duty network engineer then

that could well mean you

um you control the damage caused by the

incident and ensure none of the evidence

is spoiled to the best durability

first responder initiates the escalation

procedure so you'd inform um

the legal authorities whoever that may

be and um internal company management

and bosses

e-discovery or electronic Discovery

refers to a pre-trial procedure where

the parties exchange the electronically

installed information this could be

emails exchanged between different

employees it could be spreadsheets a

video conference calls that have been

recorded

um anything electronically really that's

pertinent to the case

and it's different from paper documents

because it's not actually tangible

um and it could obviously be saved in

one place or saved in multiple places

over the cloud and have different

versions of it

some examples for electronically stalled

information are as follows

emails voicemails documents

presentations databases websites and it

could be for a certain period like a

database copy of a database from a month

ago or a year ago or whatever it

obviously varies

the electronic Discovery process this

involves identifying preserving

collecting processing reviewing and

producing the document to the opposing

Council

you could actually have to produce it

for your own lawyers as well and to

prove your case

now the gender custody is a document and

you could have evidence labels if it's a

physical hard drive for example and this

would include the person who seized it

who they handed it to

um I'll go into some of the stuff on the

next slide

let's um let you know the location of

the evidence so if it's finally handed

to a and property

retention department like in the police

property area

then um that would be the last person to

have signed for possession

starts when it was collected

requires who collected it the date and

time description where the evidence was

stored it's not only given an exhibit

reference as well certainly if it's

collected by an experienced

um forensics person it'll have some

reference number on it

um how it was initially secured which

software can be used to view it

the transfer history the evidence and

here's some evidence labels

and not necessarily just for um

Okay computer forensics if you can see

on the left it's received from and by

date time the agency the case number the

badge number

and then on the right the submitting

agency again and chain of custody

so the child across today is the

transfer history showing the information

every person or every normally person

could be a department and along with the

names and the person signed in the dates

and where the evidence was stored and

secured

now if there's a problem if person a has

signed it person B assigned it and then

person D signs a label we've missed out

what happened one person C held that

evidence and if the chain of custody is

like broken it means the evidence could

be tampered with and then it'll be down

to a court to determine whether or not

that evidence is still admissible

and the evidence

um but I've just said that it may not be

admissible it could be useless in court

all right there's a document or a

process called Legal holds used in

litigation but it could also be a

preservation order basically requires an

individual or organization to preserve

all information that may be required by

an opposing party because of anticipated

litigation

data should be preserved such as emails

um preventing things being deleted

because of um a certain period of time

has um transpired or expired sorry

and there's an Interventional hold on

the routine destruction until the

litigation end so you know as backups

normally get wiped

and um replaced with fresher backups

then um you wouldn't be able to do that

you'd have to keep hold of the evidence

if a crime scene is a physical location

then the area should be first secured

once the area is secured is important

together as much evidence as possible

normally this person will be properly

trained and qualified and just to go

through how the evidence is collected

photographed preserved and who it's

handed on to and in what manner and some

types of evidence and not that it

applies to computers but

um say blood on clothing that has to be

dried in a certain way in order for it

not to um all go stale and lose all the

DNA evidence

if the crimes are cyber crime and then

the location should be secured to stop

the evidence being tampered with

it doesn't mention there but obviously

if there's remote access available to

the device that has to be born in mind

as well in case somebody can

inadvertently log in and wipe the

information

a hard drive should be kept in a secure

Drive is probably going to become harder

and harder

now we're using cloud computing

uh collect all

um digital evidence in a manner

permissible to the court it depends on

the court obviously

when Crumbs are committed the first

responder at the scene controls the

damage this could well be you as I've

said so down to you to use your

technical know-how to preserve data as

much as possible

foreign

ensure nobody else tampers with it again

you'll be advised by law enforcement as

and when they arrive but down to you to

stop people walking all over things or

picking them up or moving them which

have seen happen when I was in the

police

during the course of the investigation

the investigators collect as much

evidence as possible

the technical city is established from

the moment of the initial collection

until the investigation finally ends if

it has to be transported the data in

some way it should be done so securely

to prevent tampering again this is the

chain of custody

uh when the investigations finally

complete the forensic report is made

available in a format that can be

understood by non-technical person and

normally because it's been presented to

the jewelry if it goes to um a jury

trial

okay we've mentioned um the legal hold

must keep that information into the

litigation ends

just a few steps in the basic forensic

process

this should be a process in place

according to National Institute of

Standards and Technology

the following steps collection

examination analysis and Reporting

collection is the first phase where data

is identified labels and recorded and

gathered

could well be photographed in situ also

examination uh it's the data's

forensically process using automated or

manual methods

analysis the results of the examination

are analyzed to get answers

and then reporting the results are

reported

details the actions carried out the

tools and procedure used who did it and

when and why

Okay so we've covered a lot here so just

to recap we've looked at forensics and

computer forensics

the first responder

electronic Discovery in the chain of

custody

legal holes securing the crime scene

the high level View

steps in basic uh forensics collection

examination analysis and Reporting so

that's all for now thanks for watching

[Music]

thank you

welcome to module 18 lesson 3 safety

practices

another new addition to the topic and

it's something that has been growing

over the past few years and so this has

become a recognized area where you go

and get qualified in a risk assessment

or whatever it's called in your

respective countries

in respect of

um certainly data centers the safe

storage

um manual handling what to do in the

event of an emergency a fire or other

disaster how to keep

um the equipment safe and comply with

all of the

um different certifications and if you

want to be a Data Center

and keep people safe also

so look at the data center and the need

the environment heating ventilation and

cooling HVAC

how HVAC works

typical hot cold oil conditions

rack mount servers rack loading

power distribution and fire risk

the impact of Fire

types of their suppressant agents you've

got available to install wet pipe dry

pipe and gas

how to lift stuff up without getting

injured anti-static it's funnily enough

anti-static if people laugh about it and

don't think about it but it can actually

fry vital components in your devices

stabilizing the Iraq and the material

safety data sheet which is another

item added to the syllabus the MSDS

all right I'm sure you've heard the data

centers and if you're very lucky you've

actually got to work in one or will be

working in one great place to work

there's a definition on Wikipedia it's a

facilities used to house computer

systems and Associated components such

as telecoms and Storage

generally includes redundant backup

power supplies Communications

environmental controls

EG air conditioning fire suppression and

various security devices

why do we bother it basically helps

organization centralize the entire

Computing resources into one location

where they can have a uniform procedure

for insulation upgrades out of hours a

redundancy a whole bunch of stuff

uh reduces the TCO by consolidating all

your power and cooling otherwise you'd

have to have 10 20 30 40 racks spread

among different departments or different

buildings or different cities making

things pretty difficult to control

racks and rackmatic servers are used in

data centers at the moment I'm sure the

future will uh have something completely

different you've got the servers storage

arrays and power distribution units all

the other devices and internal

components generate a lot of heat

the heat needs to be removed because it

obviously affects the electric equipment

to the point where it reaches a

threshold that it can no longer function

and then the device will fail and you

may have had this on your home computer

if your CPU fan

has stopped working or this tumors dust

or dirt inside your equipment then it

starts to lock up and finally fail I

know that's happened to me

since heat effects of reliability we

need to keep it cool this requires

removing the hot air and moving in cold

air just like your PC chassis but on a

much larger scale

I'll turn cold air within the data

center shouldn't be mixed and for this

reason you've got the hot oil and the

cold oil Arrangement this is for your

ventilation

if the cold air mixes with a hot air

without going through the equipment then

it becomes useless

so HVAC stands for heating ventilation

and cooling which is an entire set of

systems procedures best practices and

companies that will help you plan and

manage and install all of this

provides the optimum temperature and

indoor air quality so you've obviously

got to have an environment that works

best for the equipment but also the

engineers can go in and manage and

survive in

the HVAC system not only keeps things

cool and keeps things humid obviously

not too humid but there has to be a

certain level of humidity in there and

removes contaminants from the air also

cold air is pumped from the HVAC system

into the cold aisle as an as an input

for the servers

the server is pulling cold air from the

front to cool themselves and they

exhaust hot air which goes into the hot

tile

now my experience when I've gone to Data

Centers is the the better ones I've got

doors to get in and out of the cool

aisle

the Hostile

um they're certainly the ones I've been

to don't have the doors so you'll be

walking through an area that feels quite

warm you'll open the door to go to the

front of the servers to connect or do

whatever obviously shooting the door

behind you and it'll be very cool in

fact you'll probably need to wear a

couple of layers of clothing

the AC duct carries the hot air from the

hotel to the HVAC to cool it again and

exhaust it elsewhere

typical hot cold oil conditions the cold

air temperatures range from 55 to 78

Fahrenheit they haven't listed this in

Celsius so I presume this is for the

American viewers the hot oil temperature

goes from 73 to 96 Fahrenheit

and the amount of heat carried by the

stream of air exiting the heat load

should be 15 to 20 degrees Fahrenheit

rack mount servers I don't know if

you've seen many of these I've seen a

lot over the years the rack contains the

servers the servers have a different

form factor than your normal desktop

servers these are these obviously need

to be

compliant to fit into a rack taking over

so many

um units uh use they call it sometimes

one two and so on

they need to have the correct eyes so

you can screw in the screws to hold it

into place securely front and back and

most of them actually you can pull open

so it pulls out from the rest and you

can do various things without having to

shut down the server or the cables

coming loose larger up Mount servers and

Equipment are stored at the bottom so

the heavier stuff at the bottom to

ensure the rack doesn't tip over

Rock loading should not only seed the

weight rated capacity of the raised

floor to ensure that the race floor

doesn't collapse because it's

overweighted everything has to be

documented planned and measured so you

spread load over inside one rack and

among a multitude of racks so you can

have the heavier stuff going at the

bottom of 10 different racks the next

heaviest goes on top on 10 different

racks and so on rather than having one

rack with all the heavier stuff because

it could if it breaches a loading it's

obviously going to break through the

floor

uh the power distribution your data

center is normally connected to multiple

power grids

um and even after that you could have

the one the one I used to have my

equipment at had

um

massive generators that would take over

and it wasn't one generator the

generator had a backup generator as well

so there's three levels of redundancy in

case there was a power cut for whatever

reason

if you've got two grids if power is lost

on one grid and certainly where I live

in Australia you get power Cuts quite

regularly which is a strange phenomenon

now to experience

nowadays for devices with redundant

power supplies power comes from separate

circuits providing redundancy

so it would be

um it wouldn't be great redundancy to

have your redundant power supply both

connected to the same extension lead

because if the

extension lead goes down or the power

supply providing power to the extension

lead then you lose both your power

supplies redundant and Main

as a data centers power requirements are

determined by taking into account the

power requirements of all the equipment

and you've got a feature

um future growth so you can't just plan

for what you need now you need to plan

for however many years in the future in

the company's business plan

uh you need to ground all equipment

separate to

um other grounds

fire and demand for the power increases

with the

um amount of equipment a lot of the

cream equipment with increased power

consumption I can find a small spaces

and susceptible to fire accidents

again this is down there due to heat

obviously fire will be catastrophic

data centers are fire detection systems

that detect the fires where they detect

smoke I think before the fire

you've got portable fire extinguishers

for engineers to use if they

somehow set something on fire or see a

small fire

data centers have emergency power off

switches which are big red patents on

the wall that cut off all power

obviously if you do that it's um a

constitutes an emergency because all the

servers don't really um deal with hard

power shutdowns very well they normally

need to be correctly um shut down

following procedures faster person

agents put out the fire

you've got to choose the correct one

obviously if you even if you go to a

local hardware store and choose a fire

extinguisher there's some for um the

kitchen some for papers and some for car

fires

there are three types wet pipe dry pipe

and gas

the wet pipe is basically a water that's

held within the pipe under pressure and

it breaks a little seal which you can

see in the picture there the little red

seal and that um when that breaks it

lets the water come out

and obviously soaks everything with

water and that's the end of your

equipment

and it will bring your data center down

the drive pipe is the same as a wet pipe

but the water's not kept in the pipes

and the reason is it accumulates

moisture and if there's a drape it can

damage the equipment and obviously

um could cause rust

since the dry pipe is a water-based

system the disadvantage is the same as

the wet pipe

now you've got gas suppression

suppression which is the norm in your

data centers it basically starves the

fire of oxygen and the fires need oxygen

in order to generate the Heat

clean agents such as fm200 remove the

heat from the fire and here's some large

industrially scale heat agents

and inert gases such as carbon dioxide

deprive the fire of oxygen

you do get immediate recovery of

business operations you've obviously got

to vent the area before people are

allowed back in otherwise they'll just

pass out

and and you've got to have training for

the staff

it doesn't actually mention I didn't put

in here but you obviously need an

evacuation plan so that there's normally

a diagram in several key places and and

signed exits

as mentioned in the syllabus but I just

thought it was so obvious because we all

see them wherever we go even coffee

shops have got fire exits of fire escape

plans

lifting techniques well you can see this

guy here is bending his back not his

knees which isn't a recommended way to

do things

easiest way is to adjust houses through

improper lifting don't really lift the

equipment if it weighs more than a

quarter of your weight lift with your

legs with a straight back obviously if

you have injuries especially back

injuries then don't attempt it and a lot

of the time there's lifted equipments

there that will oyster for you or hold

it in place while you screw things or

unscrew them and Slot them in

anti-static static electricity as I

mentioned at the start will fry various

components and that's happened to me

when I've installed motherboards and

other devices I've just heard a Little

Fizz and some things

um something's broken so use anti-static

devices

there's anti-static bags and also wrist

straps that you can connect to your

wrist and then connect to an earth

somewhere that will prevent the

um

causing the spark somewhere because as

we walk around we're generating

electricity static electricity

stabilizing Iraq is important to have a

correctly stabilized rack with the um

fate which are all adjustable racks are

not stable or likely to collapse at any

time

um you put your large equipment in at

the bottom

and the lighter at the top there

and moving on to another syllabus item

is the MSDS the material safety data

sheet which you'll go into this is a

document that contains information about

hazardous chemicals

used as a primary means to communicate

and the chemical hazards to staff I

presume you'd go in some sort of

training course for for this not um

not just read something on a wall

preferred by the manufacturer or

supplier of the chemical

you have to make the MSDS available in

your workplace for each hazardous

chemical or a mixture of such hazardous

chemicals

it should be ready available to all

those who may come into contact with

such hazardous chemicals

the occupational safety and health

administration and I presume these are

American different countries will have

different organizations or

Administrations

they're part of the US Department of

Labor create the hazard communication

standard to ensure that all

um chemicals that are hazardous are

evaluated and the information is

correctly passed

should be in English this should be

include 12 items mandated which will go

through briefly

the name of the chemical the physically

chemical pop and properties such as

color and odor so you can recognize it

if it does have a color a lot of them

have odors added

such as their natural gas has an odor

added certainly did in the UK so you

could smell it if there was a leak and

before that and people didn't know that

the house was full of gas and uh lit a

cigarette and that was the end of them

physical hundreds uh hazards such as

explosiveness or could it react with

something

uh health hazards such as corrosive to

eyes or skin you normally have that in a

diagram as well

primary ways you can enter your body

such as always breathing

allowable limits of exposure before you

get seriously injured or die

carcinogen

precautions before you use it masks or

goggles special equipment

and do you need any gloves

protection

and Engineering controls

first aid if it all goes wrong normally

as the number of the Emergency Services

the date when it was prepared the

document and the last revision

contact details of the person who's

responsible

all right we've covered a lot here and

it's all your health and safety stuff

your data center your HVAC

hot and cold aisles and a correct

loading of your racks

fire risk fire suppression and the

impact your type of Agents

lifting without injuring yourself or

others

you're anti-static and rack

stabilization and your MSDS so that's

all thanks for watching

[Music]

foreign

lesson one common wireless issues

and we look at signal loss interference

signal to noise device saturation

bandwidth saturation

untested updates getting your SSID wrong

so you can guess how to fix that one

power levels open networks Rogue access

points

wrong antenna for your device

incompatibilities wrong encryption and

bounce most of these are pretty Common

Sense actually but I've put these in

because

um it's on the syllabus and if you've

got a home wireless device or even

you've used Wireless on your mobile

phone you probably have to troubleshoot

most of these issues

um but we'll cover them nonetheless just

in case signal loss you've got no signal

or low signal

there's connectivity and there's no

connectivity when there's no signal

there's latency and inconsistent

connectivity when the signal strength is

low

client devices closer to the access

point especially when you're at home

actually

if you've got a your wireless access

point in a different room and if you've

got an older house certainly in the UK

most of the walls were made of

um thick concrete

and uh they built the houses to last

there was no or very few false walls

inside houses with just plasterboard or

wood

um obviously you can install

um a booster as well you can install

something in your power unit and it will

boost the signal or act as a repeater

ensure there's minimal obstructions

metal studs is another one that will

reduce your um

connectivity or signal ensure the

antennas allow communication as well

sometimes the antennas come in a box

or um they're not attached or they're

just pointed in the wrong direction

interference other wireless devices are

using the same frequency uh you can also

have interference from microwave ovens

and cordless phones it tells you this in

the documentation but most people don't

read it when you're installing your

wireless router it'll have a pictures of

the kind of things that will interfere

with your signal

you'll get latency and inconsistent

connectivity avoid interference pretty

obvious as I said and but you can avoid

having your devices near to these things

like your ovens or cordless phones

um you may be able to change your

channel as well if it's got the same

channel as your cordless phone uses

overlapping channels because of the

wireless access points are used in the

same frequency there's automatic channel

selection normally on your devices but

if you have any

reasonable amount of ability you should

be able to log in and change your

channels

uh avoid uh you can correct it by

avoiding the manual selection of

non-overlapping channels

signal to noise ratio it's the ratio of

the Wi-Fi signal to the outside

interference or noise noise is in

respect of Wireless have a negative

impact on your wireless signal other

Wi-Fi signals don't count as noise

this again will give you connectivity

issues or latency

signal levels and noise levels can be

visualized as heat Maps

the ratio of 10 to 15 decibels is

considered unreliable

16 to 24 is weak

issues can be avoided by increasing your

signal strength and decreasing the noise

I told you all this stuff was obvious

device saturation is when more wireless

devices are connected to your network

you'll get a decrease throughput that's

probably your fault for letting your

kids have access to phones at home or

other wireless devices bandwidth

saturation is when one or more devices

transmit a large quality of quantity of

data

um I would imagine received also so if

somebody in is there watching YouTube in

another

room in the house and that'll do it

untested updates

um updates can obviously break things if

they haven't been uh correctly tested

especially with regards firmware I've

even recently installed a an SSD drive

in my

home computer and while I was just

researching it I found that the latest

firmware drive from the manufacturer

actually was wiping everyone's data

which is catastrophic for most of us and

the manufacturer was aware and they said

they were releasing an update but the

problem is if you downloaded the update

it was too late for you

back up your last working config not

sure how you do that with your firmware

actually but you can research that

yourself wrong SSID all you need to do

because they're case sensitive you could

have the wrong case or just mistype

something

a lot of the time when you type these

out you can't actually see the letters

you're typing unless there's a an option

for you to do that so you could well

have typed out the incorrect password

but you can't see it

avoid having the client device and the

access point set to use the same SSID

power levels uh users will experience a

big coverage area or small

coverage area because of low power

levels and access points big coverage

areas occur because of high power levels

and access points

and avoid it by adjusting the power

levels for a good coverage area

open network is an unsecured wireless

network you used to see a lot of those

around but most people now have become

Savvy or the default settings on the

home routers I've got security chosen

automatically

unauthorized devices May connect to the

network if it's insecure so obviously

change the security settings if this is

the case

Rogue access points as an authorized

access point installed on the network

normally employees uh just for a bit of

convenience will go into their desk and

plug something in to get wireless access

malicious attacker can install Rogue

access points uh thus getting them

access to the network

wrong antenna type signal coverage

depends on your type of antenna so you

could have no signal or poor signal or

um a good signal but far away from the

access point

okay

omnidirectional and directional are two

main types of antenna omnidirectional

gives you 360 degree degree patterns

suitable for inside an office conference

area

directional will give you a signal in a

particular direction so your coverage is

limited to that One Direction

you got a yagi

parabolic grid patch and panel antennas

the jaegi and parabolic grid are used to

connect one building to another you must

have line of sight so if somebody's got

a tree there or something else temporary

or permanent then it's going to cause

you issues that you'll have to

troubleshoot

and if you see if there's

incompatibilities users may not be able

to get access to the WAP the settings

may be incompatible standard supporting

if you've got a very old

um Wireless car that you've got on your

device a PCI card or USB it might not be

compatible with your other device

so 802.11a is not compatible with 11b

and 11g

you've got to look at what is compatible

so B is compatible with G and vice versa

some are backward compatibility

compatible others aren't

uh wrong encryption you may not be uh

get a connection with the wireless

access points

the client device and wireless access

may have different encryption settings

so you need to check that

um what's configured on your access

point is matching on your wireless card

or wireless device whatever you're using

so do configure it correctly examples

are web WPA and WPA2

bounce is when your signal bounces off

an obstacle without reaching the

destination you can get weak or no

connectivity you need to remove the

obstacle obviously sometimes that's

easier said than done so if it's a big

thick concrete wall in your house don't

don't knock it down because your roof

will fall down you need to either get

some sort of booster

or um move where you're connecting from

or just find a alternative connection

type

such as connecting through the um

ethernet devices that were plugged into

your power

all right so we've covered a lot a

signal loss interference signal to noise

saturation bandwidth saturation

untested updates wrong SSID and your

power

open networks Rogue access points

the wrong antenna type incompatibilities

are on encryption and bounce that's all

for now thanks for watching

[Music]

thank you

welcome to module 19 lesson 2 Common

copper cable issues that's a mouthful

so some of the common issues you'll

experience as a network engineer

our shorts opens incorrect termination

crosstalk

Emi distance limitations attenuation the

cable issues

shorts is basically short for a short

circuit it allows the current to travel

in a path that wasn't intended and the

cable wasn't designed for a couple was

in the cables are insulated so they

don't come into contact with each other

if

um there's some sort of issue a lot of

the time it's because it's frayed

somebody's bent the cable around a Bend

or just done something with it or folded

it too many times and unfolded it then

the cables can touch each other and then

you've got a short circuit you depended

on how bad it is you'll have

intermittent connectivity issues you

could use a TDR that will locate the

short in the cable this is one of your

troubleshooting tools that you could use

an open refers to an incomplete

electrical circuit in which there's no

current if one of the copper wires

inside the cable is cut or just broken

for some reason then you've got an open

circuit you would normally then have no

connectivity

again you can use a TDR that can be used

to locate openings in the cable

incorrect termination generally happens

when you've made your own cables or your

cable engineer has done it and just made

a mistake or done it too quickly or just

not

and been watching what they're doing and

it's obviously human error then don't

happen it doesn't happen as much in um

professionally made cables so you

haven't properly terminated as per the

standards you could have got the wires

mixed up or not squash the um the RJ45

connector onto the wires correctly and

it's a bit of an art to it so you could

have no connection or intermittent

connection issues

straight through cables should be

terminated either using

t568 a or b

crossover cable has got a on one end and

B on the other so pins one goes to three

and two goes to six on the other end

use the cable tester to check if your

Cable's properly terminated and what

type it is

crosstalk is when the signal from The

Wire interferes with the signal on

another wire

less of an issue now with modern

um shielded twisted pair

uh cables

you measure with the cable tester or TDR

again the issues avoided if you buy a

professional cable basically because it

will be twisted properly

two types of crosstalk that you may be

asked about in the exam near end and far

end

and near end is refers to the crosstalk

that occurs at the terminated end of the

cable where the crosstalk has been

measured so this is where you're doing

the measuring

occurs near the connectors terminating

the cable far end is

um on the far end of the cable from

where you're doing the measurements

occurs near the connectors terminating

the far end of the cable

electromagnetic efference is normally

when you've laid the cable yourself and

it's gone

through or near some device that emits a

strong error signal

an emo signal also called radio

frequency interference

generate generated

um

by fluorescent lights electric motors

dynamos things like that so it could

happen in a workshop or when you haven't

properly housed your cable or it's not

running under the floor and you're

running it through the ceiling and it's

going through the

um

fluorescent lights

data transmission of copper cables is um

obviously disrupted when it's exposed

and it could be intermittent it could be

fine during the day and then later on in

the evening when somebody starts turning

the lights on it could be affected

avoid if you separate the power source

from the cables or by using shielded

cabling

you may have to buy a special type of

cabling if you're running your cables

through devices with a lot of very

powerful

um electrical signals

obviously there's distance limitations

per cable lost the signal when it

travels over a long distance you could

then have connectivity issues so if

you're running your cable over

120 meters when it's recommended 110

then you may well have issues

attenuation or DB loss refers to a loss

of signal strength the signal strength

is measured in decibels

uses experience degradation in network

performance you can avoid it by

um using cable runs within the maximum

supported distance using a signal

booster you probably need specialized

advice for this to be honest if you're

installing in a commercial premises

remove broken or damaged cables

and miscellaneous of the problems uh

verify the cables are present and

plugged in yes I've been asked to

troubleshoot devices when somebody

hasn't actually put the cable in yet it

hasn't been installed at all or

somebody's removed the cable for some

reason because they want to use it

somewhere else and not realized that

that is connecting to an end user or a

server

or some of the device

make sure the network adapter is enabled

and it has a valid addressing sometimes

devices have been up for years

and

um millions of packets have been passed

in in and out and it just needs

resetting or rebooting or the address

needs and refreshing on it it just

happens sometimes every period of time

make sure disabled ports are enabled for

connectivity sometimes ports are

disabled for security and you could plug

in a new user into a certain port on a

switch for example but that Port has

been disabled

you can have bad cables again sometimes

we bend them or just over time for

whatever reason the cable goes bad

misconfigured switch Port it could be

the wrong

um duplex setting or speed setting or

something else on there and it may not

work

misconfigured network card or a network

card that's failing or failed

software drivers I've mentioned

elsewhere that can cause huge problems

and it's not a problem you can actually

easily see until you start doing a bit

more research

all right so we've covered shorts opens

termination crosstalk Emi distance

attenuation and other problems

that's all for now thanks for watching

[Music]

welcome to module 19 lesson 3 common

fiber cable issues

so look it's troubleshooting uh

supported distances categories of

multi-mode fiber the bend radius

dirty connectors I think you can guess

what that one's about attenuation a

wavelength mismatch fiber type mismatch

so the bottom line with fiber cables is

uh if it's faulty it can't transport

data it tends to be either a working or

not working situation whereas with

copper you may well have a period of

time where the the performance just

deteriorates when you get in packet loss

or intermittent um connectivity and you

normally easily troubleshoot that by

just swapping the cable out if it all

works then it points to the fact that

the cable was faulty and they're so

cheap you just throw them away

obviously um fiber cables are not so

cheap

first place to look will often be the

LED next to the ports where you've

plugged the cable in if it doesn't light

up then you've got a number of possible

reasons the cable's not um plugged in

properly at both ends the cable could be

broken somewhere

now here's um

the troubleshooting flow chart for fiber

cable

um well worth maybe just printing the

screen and just following it through

plug it into a different port does that

Port light up then and it shows you it's

a problem with the port

um just a few simple troubleshooting

steps really

all right don't look into the cable when

you've got the other end plugged in

because the laser will go directly into

your light and it could cause damage so

use um you could well you could actually

point it at um a white object or a wall

or at your hand

um but read the documentation that comes

with the cable to make sure you're doing

the correct thing there are obviously

electronic devices that you can also use

when you can connect two devices such as

a server adapter to a switch using a

fiber cable the TX Porter one end should

always be connected to the RX Porter the

opposite end normally you'll get a

housing

that both ends of the cable will connect

to and that can only plug in one way to

the device

not always the case and obviously

there's different cable types all over

the world but um normally you'll

um

it'll be designed to be idiot proof so

we don't um cause that issue if you

connect it the other way around you'll

have no connectivity and then um it'll

show no connection

as supported distances multi-mod fibers

with 50 microns and 62 microns can

support data up to 500 meters and 175

respectively again read the label it

comes with your cable in

um you might you may well be lucky

enough to have a professional company

coming into your cabling for you and

then again you may have to go and swap

some cable out or install a new device

without the aid of this company so you

do need to know

multi-mad fibers are categorized further

by Optical multi-mode or om designator

these are labeled from om1 to om4 just

check the uh table and

um you've let you've normally got a

label on your cable as well to see what

you do however it's stamped on the side

and just check the specifications and

allowances

when you troubleshoot in check whether

the cable supports the speed and

distance of the link between the devices

Bend radius most fiber optic cables are

made of glass

a sharp Bend at some point they are

pretty flexible but if you bend it too

much it will break the glass the bend

radius refers to the smallest bend a

cable can withstand again if you start

wrapping this Cable Round and Round a

pole in order to take up the slack then

you could well check and break the bend

radius and rendering the cable

um unserviceable

to avoid issues don't bend them

obviously or more than you have to the

otdr can be used to check whether the

cable is damaged

damage cable obviously needs to be

replaced hopefully that goes without

saying

um the broken cable some people put them

in a cable box if it's broken make sure

you dispose of it in um the legal the

legal manner so you can't throw it onto

a fire usually you'd have to have it

professionally uh destroyed or every

cycled if you've got dirt because it

uses light on the fiber cables if you've

got dirt on one end it will cause

um

problems High loss and reflectance clean

it using the cleaning methods and

supplies provided with the cables don't

wipe at the end of it on on your

trousers

attenuation signal loss over the

fireball optic cable following could be

the reasons it could have been over

stressed during installation improper

termination improper splicing if it's

been spliced somewhere could be broken

fiber again you can use the otdr to

locate the faults

wavelength mismatch

fiber cable uses wavelengths longer than

a normal light it's usually around 850

1300 or 1550 newton meters

multi-mode fiber is designed to operate

at 850 to 1300

single mode 13 10 or 1550

the wavelength is used for transmission

on the wavelengths that must be tested

for Signal losses in the cable plants

now when the mismatch fiber cables are

coupled the incompatibility of the core

sizes results in signal loss

now there's no problem if you're

transmitting light from a smaller fiber

core to a larger one but the other way

around and you'll have signal loss

the signal loss can be around 20 DB when

a couple when we could pull a multi-mode

fiber to a single mode again read the

documentation that comes with all your

cable in

so I've looked at fiber cable supported

distances and categories the bend radius

dirt on your connectors attenuation and

wavelength mismatch and fiber type

mismatch that's all for now thanks for

watching

[Music]

foreign

19 lesson 4 common network issues

there's actually entire books been

written about troubleshooting Networks

and from PC switches and routers and

it's something that requires a bit of

experience common sense

and often a plan and sometimes a bit of

good luck as well and guesswork

we're going to look at common things

that normally go wrong day to day

incorrect default gateway

broad Customs duplicate IP address your

duplex and speed mismatches

incorrect vlans Hardware failures and

DHCP DNS

interface misconfiguration cable

placements

power failures and then less common MTU

black hole Nick teaming issues

so you can create default gateway

um it depends if there's been a change

of default gateway

if the device

um

that is experiencing the problems has

had any changes

or um somebody's gone in and configured

something so it all depends on the

questions you've asked really

but if you've got the incorrect default

gateway then all traffic from your host

device is going to the wrong location

and Layer Two devices such as switches

also are normally configured with the

default gateway but you should be able

to Ping from the um switch whatever the

VLAN is to the default gateway when

you're installing it just to check it's

working

so the IP address assigned to the

default gateway may be correct and you

can check your IP configuration settings

on your windows or Linux

um device

obviously to fix it put in the correct

default gateway and make sure nothing's

changed on the default gateway

broadcast storms users can experience a

degradation and network performance and

it can actually bring down the entire

network

so the network is flooded with broadcast

traffic could be a switching Loop it

could also be a faulty network card

that's just sending a huge amount of

traffic out

and you could troubleshoot it with

Wireshark and other programs and Cisco

provide um a whole raft of tools

uh obviously having spanning training

switches will help solve the problem

it's normally there it's normally on

their body faults

duplicate IP sometimes somebody doesn't

release their DHCP address it's been on

there too long or stuck for some reason

or I've seen people manually configure

an IP address on their system for some

crazy reason

I don't know why they did it and it's

caused a mismatch

to avoid it you can change the IP

address of both or one of the hosts and

normally

um asking for it to be provided by DHCP

which most devices use

speed and duplex mismatch you can have

on your host or on a switch in fact on a

router as well

you'll have slow or degraded Network

performance or no connection no

connectivity at all

and you could have different port and

speed settings you could have 100 full

duplex on one side and 10 Meg half

duplex on the other side and you're

going to have problems normally you'll

see issues on the LED of the network

card as well and you could have um

error messages coming up on your router

or switch console and on your PC

so common causes when negotiation is

enabled on one side and disabled on the

other

it's reliable to manually configure

network speed and duplex settings for

the server and other critical links now

you may use Auto negotiation the

networks I've worked out they they

generally didn't

they had hard-coded and speed and duplex

settings for all devices

uh incorrect VLAN if you're on the wrong

VLAN you may have no connectivity or not

be able to access the resources that you

need because it's in a different VLAN

configuring devices is normally the

switch Port the end devices don't have

VLAN settings as a general rule you

would configure the switch port to be in

the corrective VLAN and make sure it's

not blocked that VLAN is unblocked for

security reasons on the switch trunk

port

Hardware failure this is a whole raft of

things that could go wrong

intermittently or just completely break

and one of the components of a device

may have failed or an entire device you

identify it with your troubleshooting

methodology and you can replace the

faulty device or the faulty interface

DHCP if this server has been incorrectly

configured

then you're obviously going to have

issues you could have one person

affected or the entire

um organization you could exhaust all of

the IP addresses on your DHCP pool you

could also indicate that you've got some

sort of attack going on some Rogue DHCP

server or the devices causing issues

we've addressed that elsewhere

DNS obviously for DNS lookups you need

to have the correct device configured

a host can be configured with the wrong

DNS server either because you've

misconfigured the DHCP server or

somebody's hard set it

so ensure the host is configured with

the correct IP address of the DNS server

on Windows you could issue ipconfig

space forward slash all and it will show

you your DHCP server address your DNS

server address

IP address and a few other

um settings that you may find

interesting

if your interface is incorrectly

configured you'll have no connectivity

or intermittent

you could have the source um or

destination device may have an incorrect

IP address or subnet so if if for some

reason you'll

um router interfaces on either end have

been put in different subnets then

you're not going to get you're not going

to get connectivity

check the ipn subnet mask of both source

and destination and check it against

your design documents

cable placement you could have slow

performance

and it could be close to a source of Emi

which we've already discussed

power failure obviously that's going to

cause issues either with the device or

part of the network or the entire

network

and most

um the higher end switches and routers

have redundant power supplies so that if

the main one goes down the second does

backup one takes over

MTU backholes this is a maximum

transmission units for your IP packets

and it depends on configurations it can

also happen with routing protocols such

as ospf

um which is outside the scope of this

course

if the packet's been flagged as do not

fragment then the router is expected to

send an icmp message destination

unreachable back to the host that sent

the packet

and the router drops the packet and

doesn't send the icmp message then the

host to the host and the router is

referred to as a black hole router

you can check the interface MTU on your

routers when you do the show interface

or you can add um some troubleshooting

software if it if you don't already have

it you can use a ping utility or you can

use a trace route you can send different

ping sizes and certainly on Cisco

routers you can go into a detailed menu

of options or send a ping packet of a

certain size to see if you're losing

packets

Nick teaming for user experiences a

degradation in network performance it

could be a Nick teaming misconfiguration

this is generally done a lot on servers

and different vendors have different

terminology for Nick teaming so again

check your documentation

uh generally you'll you'll

aggregate various Network Cards into one

logical connection

um so you could have broadcast uh storms

there'll be other issues as well with

spanning tree and um other things to

prevent the Nick team from becoming

multiple links you can use Link

aggregation control protocol which is

used on routers generally

all right so incorrect develop Gateway

broadcast storms duplicate IP and speed

and duplex VLAN assignments on your

switches check your documentation for

that and your configurations

should say Hardware failure sorry

misconfigured DHCP and DNS

interface misconfiguration issues cable

placements

power failures empty black holes and

Nick teaming that's all for now thanks

for watching

[Music]

thank you

welcome to module 20 lesson one change

management basics

we're going to look at what is a change

what is change management types of

changes and approval processes what is

documentation in respect of change

management

what is a maintenance window

what is configuration procedures or what

are

what is a rollback what is the potential

impact

what is the notification to change

now change management is a new addition

to the network plus syllabus

it actually dates back to you can trace

change the management back to the 1960s

and now it's a recognized

um

qualification and a whole area where you

can gain employment as a change

management change manager

so you could Google change manager and

ITIL which is the it infrastructure

Library

but this is bringing it into alignment

with prisoners practices where we're

managing

um changes and problems also when I

worked uh Yellow Pages in the UK there

was a whole Lotto team looking at um

change management problem management so

there's systems and procedures for

everything looking at what we're doing

why we're doing it who authorizes it if

there's a problem what caused the

problem how do we stop the problem

happening again

and it makes the entire uh business

procedure and business run more

professionally and it cuts down a lot of

unnecessary

procedures blaming Communications and

debriefing and makes the organization

work more efficiently

changes any addition removal or

modification or configuration that could

have an effect on the IT service so this

is why we need to have a set of

procedures in order to plan for a change

rather than somebody just rebooting one

of the main cool routers on the network

at the busiest time of day we need to

have some sort of procedure

so change management is a set of

processes that governs and controls the

aspects from start to finish it reduces

the risk disruption and impact on the

business

we could refer to it as CM for short

so CM aims to use the defined standards

and methods and procedures across

various teams of groups so we're all

basically singing off the same hymn

sheep this is the ITIL the it

infrastructure Library which we actually

host and some of the one of the

qualifications on howturnetwork.com I

highly recommend it because

um it people now can't just rely on

being technical

they need to have an understanding of

how they slot into the business and how

the business works the it works as part

of the overall business utility breaks

into service transition service design

and service operations

and you can see some of the um things I

mentioned here you can see change

management is highlighted there's

problem management Knowledge Management

Service testing and validation

and you slot this into your business how

your business works and how it's going

to benefit it

so change management includes a risk

assessment reducing change failures

properly implementing any changes

looking at business timelines and

service level agreements

it gives you better control a clear plan

for reverting if there's an issue

I've actually seen this when I had my

website hosted with a different service

provider somebody did a change to one of

the tables on one of the databases and

it caused outages for around three days

and I know some people went out of

business it was just an absolute

catastrophe and they didn't I don't

think they had a change management

procedure in place otherwise they could

have backed out quite quickly

I'm managing Communications this is

important where there's a central person

is responsible for from communicating

what's going to happen when it's going

to happen and then they communicate

um

just before it happens and then after to

say the changes happened and it was

um a success or failure on what's

actually

um the procedure afterwards for

following up

changes can be performed to adapt or

change business needs Hardware software

it could reactively Implement a fix if

there's some sort of major issue or bug

or attack on the network

normal changes for example a a normal

configuration or server maintenance

and something that it was generally

expected

standard change is pre-approved changes

that don't require approvals these are

things that just aren't going to cause a

problem usually for example

um

swapping out a redundant power supply

it's just not going to have any impact

and it's been tested for

um in the past

risk associated is low and does not have

enough adverse adverse effect on the

business

emergency these are changes that are

implemented on an urgent basis through

and remediate a problem it's normally

Network effect in business affecting and

it has to be done urgently you need to

have approval off um the emergency

change Advisory Board and they'll

normally have either a video conference

or a quick meeting

in order to talk about the impact on the

business because you need to look at the

entire

um structure

documentation a change request is

documented using applications

there's a variety of

um applications you can use

the documentary change request is caused

a change record it could be online or

printed issues to track the chains

throughout its life cycle from beginning

to end

this is so we've got an audit trail of

what happened and who did what and who

approved it and

Etc the change record contains key

details of the change including detail

tech technical implementation

the the technical parts will probably be

read by the um the it managers and

Technical team but they're there um for

the record

key details is who requested it why did

they request it what's the outcome

what's the point of doing it is there a

business benefit or is it going to

prevent something more serious happening

what are the risks involved

what resources that includes the teams

human resources and physical and

software resources

for example a network card needs

replacing or an update required for the

software

who's responsible for building testing

and implementing what's the relationship

between this change and other changes is

it one of a series

so the effect of one change on another

for example if you update a VLAN on a

certain device what devices what

physical ports are going to be affected

is the VLAN going to be propagated on

other switches or does it need to be

blocked

maintenance window I'm sure you've heard

of it's an agreed period of time in

which is going to have minimal

disruption

normally done on the weekends or out of

hours just depends on your business uh

procedures the author authorized

maintenance Windows predetermined and

pre-approved to carry out the change a

lot of the time

um an alternative

our server is used or whatever

um

you could have some sort of load

balancer used on all traffic is just

sent through one of the load balances so

the change could actually be transparent

to users

generally changes during weekdays are

scheduled after business hours critical

changes Friday nights and they can run

into the weekend so you can roll back

and recover if there's an issue

or changes to service assets and config

configuration items are recorded in the

configuration management system

uh server can move from pre-production

to production with a formal sign off

before it's accepted into production

such changes are to be documented for

timely support so everyone needs to know

about the fact this new server has been

introduced the configuration settings

and what the possible risks are and what

we do if there is a an issue

our rollback is basically going back to

how we were before this change happened

not always possible obviously especially

if something's completely broken and has

to be replaced and then the replacement

for example is broken also

okay so worst case there's a site

failover or business continuity plan may

be invoked this is if the entire core

system goes down is there some sort of

backup in place or what do we do

looking at the impact

there's a matrix low impact and low risk

category for going all the way to

category one which is high impact high

risk and it's a critical category low

medium high and critical

the notification to change is published

with the details of the change activity

the window of the change obviously it

only goes out to the people that are

going to be impacted

all right so we've looked at change

change management types of changes and

approvals what is documentation

what is a maintenance window

configuration procedures and rollbacks

impact and the notification to change

that's all for now thanks for watching

[Music]

thank you

welcome to module 21 lesson one Internet

of Things Technologies this is one of

the new subjects has been added to the

latest uh come to exam

they just expected to have an overview

of what these things do rather than any

detail because there's quite a diverse

array of protocols here said wave and

plus Bluetooth which I'm sure you've

heard of NFC

uh infrared

RFID

so Internet of Things

it's a network of devices appliances

Vehicles physical devices and many of

them work with sensors or softwares so

for example when you're uh so let me go

down there's a car here actually

you'll have a sensors on your car

I know I didn't want any awards for

drawing centers on your car breaks

uh which has been detected by a gold

goes into a CPU of some sort

when it detects it the wear is down and

say you've got 30 left then it will

communicate to the uh garage

a computer in the garage that will all

down whatever part you need from the

manufacturer that will go to the garage

and then you probably depending on how

advanced the car is have a notification

that your tires are worn or your garage

next time you take it in for a service

we'll have the part in stock

and um we'll be able to replace it

that's just one example of The Internet

of Things there's many of many of those

and it's just a phrase that was coined

several years ago said wave is a

Wireless Communications protocol used

mainly for home automation for example

your lighting your security your

thermostats to set it and all your

favorite settings works over a mesh

networks all the devices are

um interconnected

and is controlled by a keypad or you can

have a key fob of some sort

and plus

it's a wireless communication protocol

again monitor sensor data this could be

your heart rate tire pressure television

any number of things and it's created

and managed by the ant Alliance it's

actually a subsidiary of Garmin who do

uh the satellite technology

a Bluetooth mesh adopted in 2017 it's

many to many Communications

so the receiver can be a thing a group

of things or many things for example

you'd compare that to the unicast

multicast or broadcast

all messages are encrypted and

authenticated so it's pretty secure

are you sorry you can ignore that one

near field communications

a set of communication protocols you're

probably using this already it allows

two devices one's usually a smartphone

to communicate

now you need to be within four

centimeters of each other so you have to

be pretty close use for contactless

payments I know on my phone I can enable

it to act as my card credit card or

debit card and swipe for my phone

instead of my card quite handy if you've

forgotten your wallet somewhere as well

and you need to pay for something

infrared I'll go I'm sure you've heard

of that we used to have um this used to

be the competitor to wireless where

companies would add an infrared

communication module on top of their

building

and as long as they had line the site

they could get high-speed Communications

with another building then I can't

remember what the range was but um it

fell by the wayside really

it's similar to visible light but

slightly longer wavelength

for example your remote control

you click that and per second of holding

down the button it sends out 38 000

signals

used in Internet things for medical

Diagnostics fire detection remote gas

leak detention air detection

RFID you probably see this if you saw

the uh the newest not the newest porn

film

a bone film um with Jeremy uh I forgot

his name now

JB right now we had one of these

inserted in him and they tried to uh

unfortunately tried to shoot him with a

missile so I had to cut it out

let's um yes it's essential to the

operation on the Internet of Things

allows computers to manage all

individual things this is compared in

the picture to a grain of rice so it's

pretty smart

uses Emi fields to identify and track

tags it up and attached to objects

the attack can actually contain the

electronically stored information so

this is what's used to Target pets

for example when will a pet gets lost

somewhere it can be tagged

also using tracking Vehicles if you've

ever seen a production line there's tags

inserted on the vehicle and that updates

the entire production system as to if

it's going too fast too slow and when to

expect the next vehicle along

all right so we've covered just in brief

the Z Wave amp plus Bluetooth NFC IR

RFID just you need to be aware of these

in case one of the questions pops up in

the exam

that's all thanks for watching