Original subtitles

Now you will learn a lot more by doing rather than just watching me talk about protocols and talk about

things.

So make sure that you download this packet tracer file and try this yourself.

I'm going to walk you through a scenario and a few scenarios in this video and in subsequent videos

and labs.

But try this yourself you will learn far more by doing than by watching or listening.

You learn to ride a bicycle by riding.

You don't learn to ride a bicycle by watching someone else ride a bicycle or watching videos.

So try this yourself.

Okay.

So in this example I've got a topology consisting of multiple devices so zooming out I've got a whole

bunch of devices.

But for this initial video we're going to concentrate on this P.C. which is in our internal network.

In other words think of this as being at your home or company.

And then we've got a device that's connected to the Internet here.

So this would be our Internet reporter.

What we're going to do however is connect to a server in our internal network.

Now at home you may have multiple Internet connected devices.

You could as an example simply open up a web browser on your P.C. and connect it to your Internet router.

As an example if I open up a web browser and connect to an IP address in my network and don't worry

too much about IP addresses at this point if you don't understand them.

Basically an IP address is a number that you allocate to a device that allows it to communicate using

a protocol which in this example is IP IP version 4 in this specific example here.

I've got a Beatty home hub when you connect to Web sites such as Facebook dot com that is going to be

using a protocol in this example HDP X which is an encrypted version of a GDP.

A different protocol but that's kind of what it is.

We encrypting HDP so you may have devices at home that you can connect to.

We going to mimic that or represent that in Packet Tracer.

So on the left here I have some servers running internally.

I have a Internet router which is connecting me to the Internet as a further demonstration.

I've got an iPhone.

I could connect to that light.

That's a cue like using Bluetooth and then do something to that light in your home you may have some

devices that are connected via IP as well that light isn't using IP as in normal IP using Bluetooth.

I'm connecting to that light via Bluetooth from my iPhone and turning it on and off but this light as

an example is connected via IP so I can go on to my phone and then I could say OK let's turn that light

off.

So it's gone off.

Turn it on now the way that works is I'm simply connecting to that light via TTP IP.

You can actually look at the traffic on your home network using an application called wire shock.

I'll talk about that in a separate video but in this example let's use Packet Tracer so that we can

talk about the same protocols together.

So on this P.C. I'm an open up a desktop and I'm going to open up a web browser now before I connect

to a server I'm going to change the packet tracer mode to simulation mode so that we can see the actual

packets going across the network.

Now I need you to know some terms for the CCMA exam.

It's basically how we referred to stuff if you like at the different layers.

So when data is sent at the physical layer we sending zeros and ones across the physical layer that's

known as butts.

So the bits of data are represented on a fibre cable as light.

So as a basic analogy if there's light it means a one.

If there's no light it means a zero.

So zero one would represent.

That's why binary values on copper.

Do we have electricity or not.

So most fundamental example would be if there is electricity on a wire it means one if there is no electricity.

It means a zero.

So think of this as a light going on and a light going off is it on.

Is it off.

And that represents of.

That's so it layer one we have bits on top of that we have frames.

So at layer two we talk about a frame.

So when we sending data through an Ethan it switch which is a so-called layer two device we are sending

frames.

So I'll use these terms.

Frame is getting switched from one port on a switch to another.

So when you hear the term frame remember layer two at least three we have what are called packets so

a router which is a layer 3 device will rot packets from one interface to another and add layer four

we have segments.

So layer 1 is bits Layer two is frames Layer three is packets layer four segments and then at layer

five to seven we have an application.

Now let me warn you as I demonstrate these protocols it's going to take time because there's a lot of

information you may find that it gets a bit boring if you do then do this yourself have a look at the

protocols yourself and try and understand the messages but I'm going to spend quite a bit of time going

through layer to layers really of four and the layer seven applications to try and help you understand

what's going on.

This kind of stuff is really important to understand.

It's basic nitty gritty foundational stuff can be boring but it's important to understand you can't

understand networking if you don't understand the stuff.

So spend the time learning your protocols you will need to put in the effort and spend time learning

your protocols if you really want to understand networking if you want to become an ethical hacker you

need to understand the protocol so that you can hack them if you want to become a network engineer you

need to understand the protocols to be able to configure network devices properly and troubleshoot network

devices or troubleshoot network issues if you want to become an a good application developer you need

to have an understanding of the underlying applications many nightmares are caused today for network

engineers because of badly written applications application developers assume some of them who write

bad applications that there's unlimited bandwidth there is no unlimited bandwidth if you write a per

application it's going to make a network engineer's life very difficult as a lot of old network engineers

will say it's always the networks fault and all the rubbish comes from the top and lands on our heads

because people will blame the network even when there's an application that's at fault make sure that

you spend your time learning your protocols so that you can prove it's not a network issue but it's

an application issue.