Original subtitles

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

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

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

that combines functionality.

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

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

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

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

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

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

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

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

we often refer to these as layer three devices.

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

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

Although routers can certainly connect IP subnets

that are using the same topology,

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

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

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

Another common infrastructure device is a switch.

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

then you're commonly plugging directly into a switch.

A router commonly forwards

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

A switch determines where traffic should be forwarded

based on the destination Mac address.

Inside of that frame.

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

because a lot of those forwarding

decisions are based in the hardware of the device itself.

Many switches have an application specific integrated

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

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

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

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

using Poe or power over Ethernet.

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

that has the ability to turn on additional routing functionality,

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

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

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

It is simply connecting all of these devices together.

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

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

Unlike switches that you might find in an enterprise,

and unmanaged switch gives you very few configuration options.

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

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

would all effectively be on the same Vlan.

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

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

SNMp.

Network administrators often use as an MP to query these devices

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

And unmanaged switch commonly has no SMP capabilities.

So although you could connect it to your network,

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

But if all you need is a simple

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

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

If you're

purchasing a switch for an office or a larger organization,

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

This is one that provides additional capabilities,

especially for someone who needs to constantly monitor

and confirm that this device is working as expected.

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

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

These switches might also have configuration options

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

traffic to have a higher priority than file transfer traffic.

It's very common for organizations

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

And one way that you could prevent

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

or STP, to have STP as a configuration option

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

Some managed switches will allow you to perform port mirroring,

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

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

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

all of those packets traversing the network.

This is commonly used for troubleshooting or packet analysis,

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

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

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

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

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

This is an access point,

and it provides wireless connectivity for the local network.

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

at your small office or home office.

This is an device that only provides a link between

the wireless network and the wired network.

You'll sometimes hear these devices

referred to as a bridge, because they are simply bridging

or extending that wired connection into a wireless connection.

This is not a device that is routing between subnets,

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

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

that are on the wired network.

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

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

The access point examines the destination Mac address and determines

if that Mac address is on the wireless network,

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

One of the

challenges with connecting many, many people in a work environment

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

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

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

We have a cable from every desk

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

In that wiring closet is a patch panel.

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

and that run is a permanent run.

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

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

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

And we would then extend those RJ 45 connectors to interfaces

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

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

to the main infrastructure of a particular network.

There may be times when somebody is moving between desks,

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

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

on one switch to a connection on another switch.

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

inside of your wiring closet

to try to properly place where they should be connected.

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

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

This is a much shorter cable.

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

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

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

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

that are coming from the desks.

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

connecting to a switch.

This means that nothing

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

because all of that is punched down and permanently connected

to the back of this patch panel.

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

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

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

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

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

You simply unplug the cable,

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

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

This is the patch panel on the top.

There are cables you can't see that.

Go back to the desk

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

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

A traditional firewall is able to allow

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

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

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

These days, it's increasingly common

to see firewalls that understand application layer traffic.

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

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

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

like the internet.

But all of the traffic between those sites is encrypted.

Some firewalls can also act as a proxy.

So if someone is browsing a site on the internet,

the firewall will stop that communication.

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

over the internet, examine

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

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

And in many cases, and this is probably the case

for the small Soho type routers you use at home.

This firewall can also act as a router.

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

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

In many environments, the firewall is the device

that is connected directly to the internet.

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

for forwarding traffic.

If you're

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

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

But some devices allow you to power that system

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

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

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

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

You often see Poe used with access points, cameras,

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

Often this power is coming directly from the switch,

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

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

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

We refer to these as Poe injectors,

and this is often referenced as a mid span.

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

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

or the data connection.

And then I have another cable that's

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

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

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

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

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

eight port Ethernet switch, and you can see that anywhere

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

So ports one through eight will support Poe.

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

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

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

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

The traditional or original style of Poe is specifically called

the eye 802 .38 F from 2003.

This is the original Poe specification that has now been rolled

into the standard 802.3 Ethernet standard.

This provides 15.4W of DC power

with 350 million amps as the max current.

We improve Poe through the years, and in 2009

we introduced it 82.3 80.

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

power, 25.5W of DC power

with a maximum milliamp current of 600 milliamps.

And one of the more modern Poe standards is the Poe

Plus Plus or the 802.3 Bty.

When we're providing 51W with 600 milliamps

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

For Poe plus.

Plus is 71.3W, with 960 milliamps as the max current.

This was a standard designed to work with ten gigabit per

second Ethernet and provide power for those ten gig devices.

Before there were switches, we commonly used hubs

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

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

That's because hubs are not very intelligent devices.

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

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

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

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

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

Since everything is being retransmitted to every other interface on this device,

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

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

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

to something more intelligent, like a switch based network.

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

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

These are not devices that you would find new.

These are probably only available on a secondary or used market.

If you're using the same cable for your cable

television as your internet connection, then you probably have a cable modem

in your home.

This allows you to communicate over what we call broadband communication,

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

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

We can connect our phone lines into this cable modem,

and of course it can be used for internet data.

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

And that standard is called Docsis.

That stands for data over Cable Service Interface Specification.

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

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

There usually multiple services

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

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

This particular cable modem

also has analog telephone connections for any voice communication.

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

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

And usually that's done through a DSL modem.

Often this is technically in a DSL modem, which stands

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

that we've always used for our analog telephone.

The reason that DSL is asymmetric is because the speeds

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

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

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

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

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

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

DSL implementations depending on the capabilities from your provider.

If you are closer to the CEO,

you also tend to get much faster throughput than if you're farther away.

And if you're not connecting to the internet using copper cable

or telephone lines,

then you may be connecting with fiber to connect to the fiber network.

You need an OMT or an optical network terminal,

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

This is connecting an ISP fiber network and converting it

into signals like copper Ethernet that can be used inside of your home.

This OMT is usually connected to the outside of your building,

and it usually delineates the ISP's network from your own internal network.

We refer to this delineation as a demarcation point or a de mark.

Sometimes this mark is located in your data center itself,

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

It's important that a de mark exists so you know what

the response abilities are for each different party.

You know that any of the wiring on the inside of your house

is your responsibility up to the point of that de mark,

and then anything outside of that de mark is the responsibility

of the service provider.

This is a closer look of this OMT.

This is the fiber connection coming in from the street.

You can see the fiber label is placed there.

You can see this device has outputs for data which is an Ethernet connection.

You can plug an analog telephone to this device as well.

And there's an F connector here for the cable connection

that you plug into your television.

If you are connecting to a copper Ethernet connection,

you're using a network interface card to provide that connectivity or a Nic.

All of the devices we've discussed so far that are connecting to a wired

Ethernet connection have a network interface card inside of them.

This is a network interface card you would plug into a server,

and this card has four separate Ethernet connectors on the back.

But if you have a laptop or desktop computer with an Ethernet interface,

that also is a network interface card.

There are also network interface cards for other types of topologies.

If you're plugging into a wide area network serial connection,

or you have a wireless interface.

Those also have network interface cards.

These are sometimes built into the motherboard,

or it may be a separate adapter that you can plug into an expansion

slot and increase the capabilities of your device.

So whether you need copper connectivity, fiber connectivity,

or anything in between, you will need a network interface card

on your device to make that connection to the rest of the network.