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If you walk in a data center
for any organization, you'll find many,

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many different types of systems
that are used for network communication.

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Sometimes these are single use devices
like this switch, or it may be a device

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that combines functionality.

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For example, the Soho routers
that we'd normally use in our home

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are both switches, routers, and wireless
access points all in one device.

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For the purposes of your exam studies, you
should understand what these devices are

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and in what circumstances you should use
these devices on your network.

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A router is a device that forwards
traffic between different IP subnets.

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The router uses the IP address
that's within the packet to determine

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what the next hop might be on its way
to the final destination.

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Because this routing takes place at layer
three of the OSI model,

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we often refer to these
as layer three devices.

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And if we have a router
that can be configured inside of a switch,

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you'll see those devices referred
to as layer three switches.

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Although routers can certainly connect
IP subnets

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that are using the same topology,

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it's also common to use routers to connect
different types of networks together.

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For example, the interfaces on a router
might connect LAN,

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Wan, copper, and fiber connections
all in one single device.

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Another
common infrastructure device is a switch.

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If you're using a copper cable
to plug in a laptop or desktop computer,

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then you're commonly plugging
directly into a switch.

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A router commonly forwards

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traffic based on the destination
IP address that's within a packet.

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A switch determines
where traffic should be forwarded

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based on the destination Mac address.

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Inside of that frame.

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This is also a device that's able to
for traffic at very high rates of speed,

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because a lot of those forwarding

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decisions are based
in the hardware of the device itself.

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Many switches have an application
specific integrated

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circuit or an Asec,
which allows for very fast throughput.

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If you have a switch that's in the core
of an enterprise network,

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there could be tens or even hundreds
of interfaces on that switch,

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and many switches will also add
additional power to the switch connection

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using Poe or power over Ethernet.

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And as we mentioned earlier,
if you happen to have a switch

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that has the ability to turn on
additional routing functionality,

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we often refer to that as a layer
three switch or a multilayer switch.

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If you were to purchase
a switch for your home from a local

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or online retailer, that switch probably
doesn't have a lot of functionality.

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It is simply connecting
all of these devices together.

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If you've simply powered the switch up
and there's no configuration options

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on the switch at all, then
you're probably using an unmanaged switch.

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Unlike switches that you might find
in an enterprise,

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and unmanaged switch
gives you very few configuration options.

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For example, you can't configure any VLANs
on an unmanaged switch.

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All of the devices that you're connecting
to an unmanaged switch

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would all effectively be on the same Vlan.

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There's also very little integration
with other protocols or other devices.

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In an earlier video, we described
the simple Network Management protocol, or

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SNMp.

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Network administrators
often use as an MP to query these devices

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on their network to check for performance
or any types of errors.

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And unmanaged switch
commonly has no SMP capabilities.

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So although you could connect it
to your network,

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there would be no way to pull it or query
that device for performance information.

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But if all you need is a simple

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connectivity device that you can use
to connect all of your systems together,

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you can probably get an unmanaged switch
at a relatively low cost.

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If you're

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purchasing a switch for an office
or a larger organization,

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you're probably going to get a switch
that is a managed switch.

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This is one that provides
additional capabilities,

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especially for someone
who needs to constantly monitor

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and confirm
that this device is working as expected.

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For example, a managed switch may allow
you to configure different interfaces

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to be on completely different IP subnets,
or what we call VLANs or virtual Lans.

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These switches might also have
configuration options

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to prioritize traffic,
so you may be able to set voice over IP

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traffic to have a higher priority
than file transfer traffic.

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It's very common for organizations

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to have multiple switches
that they would connect to their network.

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And one way that you could prevent

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loops between all of those switches
is by enabling Spanning Tree Protocol,

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or STP, to have STP
as a configuration option

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on your switch, you would probably need
to have a managed switch.

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Some managed switches
will allow you to perform port mirroring,

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where you can take traffic from one port
that's on the switch

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and copy all of that traffic
to a different port on the switch.

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Ideally, to plug in a protocol analyzer
to be able to view

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all of those packets
traversing the network.

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This is commonly used for troubleshooting
or packet analysis,

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and not something you would usually find
on an unmanaged switch.

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And as we've mentioned, a managed switch
can also include a number of different

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capabilities, such as enabling Simple
Network Management Protocol or SNMp.

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If you're in the office or you're walking
through another place of business,

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look at the ceiling
and see if you see a device like this.

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This is an access point,

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and it provides wireless connectivity
for the local network.

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This is not a router
that you might find in a Soho device

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at your small office or home office.

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This is an device that only provides
a link between

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the wireless network
and the wired network.

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You'll sometimes hear these devices

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referred to as a bridge,
because they are simply bridging

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or extending that wired connection
into a wireless connection.

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This is not a device
that is routing between subnets,

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and it's not performing
any type of network address translation.

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It's simply bridging people
on the wireless network to the folks

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that are on the wired network.

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An access point makes forwarding decisions
based on the destination Mac address,

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which is identical to the way
that a switch forwards information.

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The access point examines
the destination Mac address and determines

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if that Mac address
is on the wireless network,

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or if it should send
that information to the wired network.

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One of the

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challenges with connecting many,
many people in a work environment

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to the network is that there are
a lot of cables that have to be managed.

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In this diagram, we have a number
of people that are sitting at their desk

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on the floor of a building,
and you can see there are a lot of cables.

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We have a cable from every desk

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that is going back to a central wiring
closet on that floor.

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In that wiring closet is a patch panel.

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We first would connect
all of those devices to this patch panel

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and that run is a permanent run.

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What? Somebody is connected
from their desk to the patch panel.

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We don't tend to move that cable
going forward.

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On the other side of that patch panel
can be connectors like RJ 45 connectors.

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And we would then extend
those RJ 45 connectors to interfaces

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that may be on a switch inside
of that wiring closet.

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This allows us to connect folks
that are on their desk all the way back

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to the main infrastructure
of a particular network.

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There may be times when somebody is moving
between desks,

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or perhaps they have a new person
that's hired who's sitting in a new desk.

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And those scenarios, you may have to move
someone from a connection

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on one switch
to a connection on another switch.

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If this was all one single cable,
then you would have to start moving cables

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inside of your wiring closet

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to try to properly place
where they should be connected.

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But with the patch panel in place,
you simply disconnect from one switch

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and you connect that particular port
on the patch panel to a different switch.

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This is a much shorter cable.

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It's a cable that's already labeled so
you know exactly which desk it's going to.

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And it's a change that you can make
relatively quickly.

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Here is the RJ 45 side of a patch panel
that's in someone's wiring closet.

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If you look closely behind the patch
panel, you can see all of the cable runs

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that are coming from the desks.

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And then you can see the RJ 45 connectors
on the front that are ultimately

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connecting to a switch.

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This means that nothing

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is going to change with the wiring between
a user's workstation and the closet,

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because all of that is punched down
and permanently connected

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to the back of this patch panel.

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When you need to make a change,
you simply move the cable

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that's on the front of the patch panel,
which certainly limits

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the scope of any problems that might occur
during one of these changes.

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If you have a patch panel like this
which uses RJ 45 connectors,

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you don't even need any special cabling
to make that change.

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You simply unplug the cable,

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move it to where it needs to be,
and plug it in to the new interface.

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Here's the connection
between a patch panel and a switch.

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This is the patch panel on the top.

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There are cables you can't see that.

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Go back to the desk

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and then there are smaller cables
on the front that connect from the patch

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panel and extend that connection
into an interface on the switch.

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A traditional firewall is able to allow

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or disallow traffic through your network
based on IP addresses and port numbers,

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since those TCP and UDP ports
operate at layer four of the OSI model.

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It's common to refer to firewalls
like this as an ozone layer four device.

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These days, it's increasingly common

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to see firewalls
that understand application layer traffic.

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And in those cases, the firewall would be
a layer seven device.

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Some firewalls can also act as an endpoint
for an encrypted tunnel,

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which means that you can connect two sites
together across a public network,

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like the internet.

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But all of the traffic
between those sites is encrypted.

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Some firewalls can also act as a proxy.

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So if someone is browsing
a site on the internet,

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the firewall will stop that communication.

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It will perform the browsing for the user,
receive the response from that device

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over the internet, examine

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and make sure that nothing inside of that
traffic may be dangerous or malicious,

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and then send the results of that query
back to the user.

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And in many cases,
and this is probably the case

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for the small Soho type routers
you use at home.

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This firewall can also act as a router.

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This device is making forwarding decisions
based on the destination IP address.

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Therefore, it's acting as an ozone layer
three device.

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In many environments,
the firewall is the device

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that is connected
directly to the internet.

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And so using that also as a router
allows you additional functionality

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for forwarding traffic.

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If you're

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using a desktop computer
or a laptop computer, you may be

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accustomed to connecting to a power source
to be able to use those devices.

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But some devices allow you
to power that system

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through the Ethernet cable
that's already connecting to the device.

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We refer to that type of power
as power over Ethernet or Poe.

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This allows you to run a single wire
to the device that will not only be able

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to transfer data, but also used
as the power source for that device.

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You often see
Poe used with access points, cameras,

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and anything else where power
may be difficult to run to that device.

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Often this power is coming
directly from the switch,

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and in those cases
we refer to that as an end span.

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If your switch doesn't support Poe,
then you'll need something

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in the middle of that connection
that will add power to the Ethernet cable.

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We refer to these as Poe injectors,

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and this is often referenced
as a mid span.

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This is a Poe injector on my network
that powers a camera.

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You can see the connection
from the cameras plugging into the Poe

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or the data connection.

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And then I have another cable that's

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connecting back to a switch
that doesn't support Poe.

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Once my switch and camera are connected
and I power up the injector,

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the camera now has the power
it needs to be able to operate.

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Most switches will identify what interface
can support something like Poe.

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On this switch, for example,
you can see that it's a common

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eight port Ethernet switch,
and you can see that anywhere

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it has the blue color across the top,
it will support Poe.

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So ports
one through eight will support Poe.

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Port nine looks like it's
commonly used as an uplink port.

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And since it does not have that blue line,
this interface does not support Poe.

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Different devices need different
types of power, and there are different

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standards for Poe depending on
what type of switch you might be using.

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The traditional or original style of Poe
is specifically called

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the eye 802 .38 F from 2003.

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This is the original Poe specification
that has now been rolled

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into the standard 802.3 Ethernet standard.

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This provides 15.4W of DC power

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with 350 million amps as the max current.

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We improve Poe through the years,
and in 2009

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we introduced it 82.3 80.

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This has also been wrapped into the 802.3
standard, and it provides additional

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power, 25.5W of DC power

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with a maximum milliamp
current of 600 milliamps.

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And one of the more modern Poe
standards is the Poe

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Plus Plus or the 802.3 Bty.

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When we're providing 51W
with 600 milliamps

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of Max current,
we refer to this as a type three type.

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For Poe plus.

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00:12:48,701 --> 00:12:54,206
Plus is 71.3W, with 960 milliamps
as the max current.

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This was a standard
designed to work with ten gigabit per

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second Ethernet and provide
power for those ten gig devices.

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Before
there were switches, we commonly used hubs

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to be able to connect all of the devices
on our network.

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Sometimes you'll hear a hub
referred to as a multi-port repeater.

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That's because hubs
are not very intelligent devices.

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Any data that's going into one interface
on this hub will automatically be copied

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and sent to all of the other interface
on this hub.

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As you can imagine, this is not
the most efficient way to communicate.

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And on top of that, we're not able to run
any full duplex communication to a hub.

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So all of the devices plugged into
this hub will operate at half duplex.

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00:13:35,581 --> 00:13:41,020
Since everything is being retransmitted
to every other interface on this device,

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as you put more of a load
and add more devices to the network,

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the performance of this device
tends to get slower and slower.

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That's one of the reasons we decided
to change from a hub based network

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to something more intelligent,
like a switch based network.

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These devices are a bit outdated for our
modern networks, and if you do find a hub,

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you'll find that they are only available
in ten megabit and 100 megabits speeds.

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These are not devices
that you would find new.

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00:14:07,413 --> 00:14:11,383
These are probably only available
on a secondary or used market.

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00:14:12,618 --> 00:14:15,321
If you're using the same cable
for your cable

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00:14:15,321 --> 00:14:19,825
television as your internet connection,
then you probably have a cable modem

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in your home.

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00:14:20,759 --> 00:14:24,897
This allows you to communicate over
what we call broadband communication,

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because there are multiple frequencies
of traffic being used over a single wire.

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This means that we can have video signals
for our television.

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We can connect our phone lines
into this cable modem,

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and of course it can be used for internet
data.

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There's a standard for sending data
over these cable networks.

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And that standard is called Docsis.

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That stands for data over Cable Service
Interface Specification.

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Many cable modems can support higher
speeds up to one gigabits per second,

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and the total speeds available to you will
be dependent on your service provider.

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There usually multiple services

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available on these networks,
and when you connect the cable,

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you can either connect to the data
that's on the internet side.

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This particular cable modem

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also has analog telephone connections
for any voice communication.

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If you're not using your cable company
for internet connectivity,

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you may be using the traditional telephone
company to provide that connection.

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And usually that's done
through a DSL modem.

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Often this is technically in a DSL modem,
which stands

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for Asymmetric Digital Subscriber line,
and it uses the same telephone lines

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that we've always used for our analog
telephone.

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The reason that DSL is asymmetric
is because the speeds

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for downloading is usually much faster
than the speeds for uploading.

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There's also often a distance limitation
with DSL, before

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the signal gets so weak that you're
not able to receive any of the data.

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That's usually around 10,000ft
from the central office or the CEO.

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It's common to see speeds
with DSL that range from 52 megabit down

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and 16 megabit up,
but you can find larger and faster

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00:16:01,493 --> 00:16:05,230
DSL implementations depending
on the capabilities from your provider.

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00:16:05,464 --> 00:16:07,266
If you are closer to the CEO,

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00:16:07,266 --> 00:16:11,036
you also tend to get much faster
throughput than if you're farther away.

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00:16:12,071 --> 00:16:14,907
And if you're not connecting
to the internet using copper cable

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or telephone lines,

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00:16:16,342 --> 00:16:19,878
then you may be connecting with fiber
to connect to the fiber network.

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00:16:19,912 --> 00:16:23,148
You need an OMT
or an optical network terminal,

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which is a device that's usually connected
outside of your home or your premise.

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00:16:27,152 --> 00:16:31,023
This is connecting an ISP fiber network
and converting it

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00:16:31,023 --> 00:16:34,793
into signals like copper Ethernet
that can be used inside of your home.

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00:16:35,094 --> 00:16:38,664
This OMT is usually connected
to the outside of your building,

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00:16:38,797 --> 00:16:44,003
and it usually delineates the ISP's
network from your own internal network.

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00:16:44,169 --> 00:16:48,874
We refer to this delineation
as a demarcation point or a de mark.

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Sometimes this mark is located
in your data center itself,

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or if you're at home,
it's located on the outside of your home.

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00:16:56,615 --> 00:16:59,251
It's important that a de mark exists
so you know what

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00:16:59,251 --> 00:17:02,254
the response abilities
are for each different party.

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00:17:02,254 --> 00:17:05,157
You know that any of the wiring on
the inside of your house

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00:17:05,157 --> 00:17:08,527
is your responsibility
up to the point of that de mark,

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00:17:08,761 --> 00:17:12,498
and then anything outside of that
de mark is the responsibility

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00:17:12,498 --> 00:17:14,133
of the service provider.

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00:17:14,133 --> 00:17:16,235
This is a closer look of this OMT.

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This is the fiber connection
coming in from the street.

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You can see the fiber
label is placed there.

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00:17:21,173 --> 00:17:25,511
You can see this device has outputs
for data which is an Ethernet connection.

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00:17:25,544 --> 00:17:28,680
You can plug an analog telephone
to this device as well.

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00:17:28,781 --> 00:17:31,717
And there's an F connector here
for the cable connection

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00:17:31,717 --> 00:17:33,318
that you plug into your television.

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00:17:34,586 --> 00:17:37,489
If you are connecting to a copper
Ethernet connection,

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00:17:37,489 --> 00:17:42,327
you're using a network interface card
to provide that connectivity or a Nic.

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00:17:42,561 --> 00:17:46,198
All of the devices we've discussed
so far that are connecting to a wired

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00:17:46,198 --> 00:17:49,401
Ethernet connection have a network
interface card inside of them.

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00:17:49,568 --> 00:17:52,704
This is a network interface card
you would plug into a server,

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00:17:52,771 --> 00:17:56,208
and this card has four separate
Ethernet connectors on the back.

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00:17:56,442 --> 00:18:00,512
But if you have a laptop or desktop
computer with an Ethernet interface,

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00:18:00,679 --> 00:18:03,682
that also is a network interface card.

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00:18:03,849 --> 00:18:07,119
There are also network interface cards
for other types of topologies.

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00:18:07,119 --> 00:18:10,122
If you're plugging into a wide area
network serial connection,

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00:18:10,155 --> 00:18:12,224
or you have a wireless interface.

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00:18:12,224 --> 00:18:15,027
Those also have network interface cards.

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00:18:15,027 --> 00:18:17,262
These are sometimes
built into the motherboard,

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00:18:17,262 --> 00:18:20,699
or it may be a separate adapter
that you can plug into an expansion

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00:18:20,699 --> 00:18:23,702
slot and increase
the capabilities of your device.

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00:18:23,802 --> 00:18:27,172
So whether you need copper
connectivity, fiber connectivity,

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00:18:27,172 --> 00:18:30,642
or anything in between,
you will need a network interface card

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00:18:30,642 --> 00:18:33,779
on your device to make that connection
to the rest of the network.