As an IT professional, you'll be working
with many different networking technologies.
So in this video, we'll look at some of the most common network
devices.
If you are connecting a device to a network,
whether it's a wired network or a wireless network,
it needs some type of hardware to be
able to make that connection.
We call this piece of hardware a Network Interface Card,
or a NIC.
So you will find a NIC inside of your printers and your servers
and your laptops and your workstations
and anything that needs connectivity to a network.
The network interface card that you'll be using
will be specific to the type of network you're connecting to.
So if you have an ethernet network,
then you will need an ethernet NIC.
If you have a wireless network, you will need a wireless NIC.
And if you are connecting to multiple types of network,
you will need multiple types of NICs inside of your device.
The network interface card that's here
is an external adapter you would plug into the motherboard,
but many motherboards have a network interface card built
into the motherboard itself.
There are also many other types of network interface cards.
This one happens to be a copper ethernet interface,
but you can get network interface cards that
have fiber connections, Wide Area Network
connections, multi-port connections, and other options.
If you've ever had to extend a network connection over a very
long distance, you know there is a maximum link that
is supported for that particular topology.
One way that you can extend this link to be even larger
is to use something like a repeater.
A repeater receives a signal, regenerates it, and then
resends that signal out another interface.
It doesn't have to make any forwarding decisions.
It doesn't have to decide which connection this is going to.
This is a simple goes in one connection
and goes out of another connection.
It's very common to use these repeaters to extend
the length of a network.
So we might be extending a fiber network,
or we might be extending a copper network.
Or it might be the situation we have with this repeater where
we're converting from one physical type to another.
For example, we're coming in at 100 megabit ethernet
over fiber, and we're outputting this repeater at 100 megabit
ethernet over copper.
In the early days of networking, if you
had to connect a lot of different devices together,
you might use something like a hub.
This is an ethernet hub.
This is a very small ethernet hub with only four interfaces
on it.
But these hubs could be tens or even
hundreds of interfaces in size.
The way that these hubs operate is
that information that is sent to one interface on this hub
is automatically repeated to every other interface
on this hub.
This is very similar to the functionality
we saw with repeaters, but the repeater was only repeating it
out a single interface.
With a hub you're, repeating it out
of multiple interfaces simultaneously.
You will sometimes hear a hub referred to
as a multi-port repeater.
The communications process on a hub
all occurs at half-duplex because
of this repeating functionality.
This means that two devices can't communicate
at the same time on a hub.
You can have one device sending traffic.
Once that device is done, another device
can then begin sending information.
If you don't have a lot of devices
on the network communicating to each other,
then this half-duplex functionality is just fine.
But as more devices begin communicating,
the efficiency of the network begins to decrease.
Ethernet hubs only operate at 10 megabits per second or 100
megabits per second.
You won't find any gigabit speed hubs.
In fact, it's hard to find 10 or 100 megabit hubs today,
because the technology doesn't scale as you put
more traffic on the network.
In these early networks where we used hubs
to connect all of our devices, we
would connect the hub networks together by using a bridge.
These bridges make decisions on what
traffic should be forwarded through the bridge based
on the destination MAC address that's
inside of that ethernet frame.
That certainly sounds very familiar,
because that's the same type of forwarding decision made
by today's modern switches.
But back in the day, these bridges
only had two or maybe four interfaces
available to be able to make those forwarding
decisions based on MAC address.
These bridges allowed us to make networks
that were a bit smaller so that each one of these hub networks
was able to operate efficiently.
And sometimes we would use these bridges to switch
between different topologies.
So we could move from an ethernet network to a WAN
network by sending that traffic through a bridge.
Instead of making traffic decisions
like a hub which took traffic from one interface
and repeated it to all of the other interfaces on that hub,
the bridge was a little more intelligent
with how it would decide where traffic was going.
It would look at the destination MAC address,
find out what interface on the bridge
that destination MAC address existed,
and then would send that traffic to only that interface where
it was destined.
A good example of a modern version of a bridge
would be a Wireless Access Point where
you have a wireless network on one side,
and on the other side, it's connecting
to your wired ethernet network.
That wireless access point is performing a bridging function.
So it's looking at the destination MAC address
of the traffic it receives, and it's deciding whether it should
send it on to the wireless network
or whether that traffic should go onto the wired network.
These days, we've extended this idea
of bridging into very large scale systems that
have hundreds of ports on them or are making these forwarding
decisions in the hardware of these devices.
We call these newer style bridges switches,
and we're able to support huge infrastructures with hundreds
of devices on a single switch by using this switching
technology.
The switches are performing exactly the same function
that these bridges did.
It's looking at the destination MAC address,
and it's sending that information
to the appropriate interface on that switch.
It's able to do this very, very fast across hundreds
of different interfaces by performing this switching look
up in hardware.
This switching hardware is an Application-Specific Integrated
Circuit, or an ASIC.
And it's this hardware switching that
allows us to scale this up to hundreds of interfaces
on a single switch.
If you look at the core of an enterprise network,
you'll probably see a switch like this with hundreds
of interfaces on it, or it may be a smaller switch that's
in a networking closet on another floor
or used in a small office or home office.
As we mentioned earlier, these switches
make their forwarding decisions based on the destination MAC
address of the traffic going through the switch.
As we'll find out later in this video,
if a device is making its forwarding decision based
on the destination IP address of the traffic,
then that is a router.
There are some switches that allow
you to have both switching functionality and routing
functionality within the same device.
We refer to these as multi-layer switches or layer 3 switches.
If you're installing a network switch and you need very basic
functionality, then you'll probably
want to use an unmanaged switch.
There's not a lot of configuration
involved with setting up an unmanaged switch.
You simply turn it on, plug in all of the devices,
and they can all communicate to each other.
There's usually not even a configuration tool or utility
you would use to configure the switch.
You simply connect all of the devices,
and they would all communicate across the same virtual LAN.
This also, obviously, would not integrate
with other external protocols.
If you needed this switch to be able to communicate back
and forth to a management station via SNMP,
then you probably wouldn't use an unmanaged switch.
The trade off, of course, is that the cost of the switch
is lower if you don't have to support
all of these other features.
So if all that you need is basic connectivity at a low price
point, then you may want to consider an unmanaged switch.
Many organizations, though, need additional functionality
in their switches.
And in those cases, they would purchase and install
a managed switch.
Managed switches allow you to configure different VLANs
on different interfaces, for example.
You might also be able to connect switches together
in a trunk.
You might also hear those referred to as 802.1Q.
There might be traffic prioritization on the switch
so you can decide what types of traffic
have a higher priority than other types of traffic.
There's also some redundancy support
you may be able to configure in a managed switch by using
Spanning Tree Protocol.
And our network management station
can communicate to these devices using a specialized
protocol called Simple Network Management Protocol, or SNMP.
And for people that need to do troubleshooting on the switch,
you can set up port mirrors, so traffic
can be mirrored from one port to another.
This allows you to connect a network analyzer
to one of the ports on the switch and copy traffic
from any other port on that switch to watch the traffic
flows across the network.
A device that makes forwarding decisions
based on a destination IP address is a router.
These are usually standalone devices,
but sometimes that routing functionality
can also be integrated into switches.
We usually refer to those as multi-layer switches
or layer 3 switches.
It's also very common to use routers to connect
different types of topologies.
So we may connect a serial WAN link, an ethernet copper
connection, and an ethernet fiber connection
all on the same router.
Many organizations provide access to wireless networks
by using a Wireless Access Point, or a WAP.
Although these wireless access points
look very similar to the wireless router
that you might use at home, the operation of these devices
is quite different.
The wireless router, you have at home
is not only a wireless device.
It's also a router switch.
It has other functionality as well.
In comparison, a wireless access point
is simply extending a wired network onto a wireless network
and allowing connectivity between those topologies.
A wireless access point is making its decision based
on the destination MAC address.
Therefore, it's acting also as a bridge.
If you walk around a large facility such as a hospital
or a university, you'll notice there
are a large number of wireless access points
as you move from building to building.
And of course, someone has to manage
all of these wireless access points on the network.
To be able to centralize this management,
these organizations use a wireless LAN controller.
This allows you to have a central management console
to be able to support hundreds or even
thousands of wireless access points
wherever they happen to be on your network.
If you need to deploy a new access point, change
the configuration, update software, or anything
else associated with the management of that device,
you would use one of these wireless LAN controllers.
This is usually a proprietary system.
So if you have a Cisco access point,
you're probably using a Cisco wireless LAN controller.
Although we're showing a physical device here
to represent a wireless LAN controller,
there is some wireless LAN control software
that runs in the cloud.
So you can simply connect to the cloud-based controller
from anywhere you happen to be able to manage
all of those access points on your network.
Many organizations use firewalls to be
able to manage the control of traffic flows
through their network, especially
traffic flows that are going to or coming from the internet.
A traditional firewall allows you to filter information
based on the UDP port number or the TCP port number.
You may sometimes see this referred to as OSI layer
4 filtering.
But modern firewalls are able to examine everything
in that traffic flow, including the application that's in use.
So a security administrator can tell the firewall
to allow database transactions but prevent file transfers
through the network.
Many firewalls also rely you to create encrypted tunnels
to and from that firewall.
So if you're off site, you still need connectivity
to the corporate network.
You can connect over a secure channel
to the corporate firewall and then
be able to communicate to your internal resources.
You might also even find older firewalls
that act as a proxy, which means that they
sit in the middle of the communication.
If you wanted to surf a website, you would send that request
to the firewall.
The proxy firewall would then make the request for you,
receive the response, check through the response,
and make sure it's appropriate for you
to view and then send that traffic to you.
It's also common to see many firewalls used as a router.
Sometimes you'll see this referred to as an OSI layer 3
device.
These routers are able to also sit on the edge of the network
and be able to do any type of routing or network address
translation based on the routing engine inside of the firewall.
A common network device on both home and corporate networks
are cable modems.
These allow you to connect to a broadband network,
usually provided by a cable television company, that
is sending data across the network using a standard called
DOCSIS.
That's Data Over Cable Service Interface Specification.
These DOCSIS networks support many different types
of throughput.
You can have slower networks at four megabits all the way
through his higher speed networks
at 250 megabits per second.
And these days, it's not uncommon to see
gigabit networks running over these cable modem networks.
Another important aspect of these DOCSIS networks
is the support for multiple services.
We're already supporting video through this network,
and now we're including the data for our internet connection
and telephone communication with voice as well.
For both home and business networking,
DSL is a viable competitor to the cable modem networks.
Instead of using the same cable used for cable television,
a DSL network is going to use the same wire
that we traditionally use for our telephones.
DSL stands for Digital Subscriber Line,
and you'll sometimes hear it referred to as Asymmetric
Digital Subscriber Line.
It's asymmetric because the download speed
that you receive on DSL is faster than the upload speed,
making it an asymmetric communication.
One challenge we find with DSL is
there is a significant distance limitation
between the telephone company's central office
and the telephone jack that's inside of your home.
The maximum distance you would be able to get on DSL
is somewhere around 10,000 feet.
If you live close to the central office,
your throughput will be faster than someone who lives farther
away from the central office.
DSL speeds generally range around 52 megabits
per second downstream and 16 megabits
per second sending traffic upstream.
And if you live closer to the central office,
your DSL connection may even be able to support faster speeds
than that.
This is a picture of a traditional company's network
configuration on the floor of the building.
You've got a lot of people out on the floor that
are working at their desk, and all of these devices
have wires, ethernet cables, that go into the ceiling
or under the floor into one of the closets that's somewhere
nearby.
And in that closet is a patch panel.
This patch panel terminates those wires
onto what we call a 110 block and provides,
inside of that closet, a set of RJ45 connectors that
go all the way back to each person's individual desk.
Also in that closet, we have our networking equipment.
So we're able to create a simple patch between our patch
panel and our networking equipment
by simply extending some ethernet patch cables
inside of our closet.
This patch panel also allows us to make changes very easily.
We can simply extend a connection.
And if we realized we wanted to connect
that user to a different switch, we
can simply move the wire down to a different switch.
If they're on a different VLAN or a different network,
then we can connect those users to a different switch
or a different set of interfaces on the same switch.
This means you only have to punch down all of the wires
from everyone's desk one time.
If someone then moves from one desk to another
or we need to plug that person into a different type
of network connection, we simply disconnect the cable inside
of our closet and plug it into the new connection.
We don't need to run a new cable from someone's desk.
We don't need to use any special tools inside of our closet.
We simply connect and disconnect using the RJ45 interfaces
on the patch panel and on our networking equipment.
Traditionally, if you were installing a wireless access
point, there would usually be two connections
for that wireless access point.
One connection was to provide the network connectivity
for the access point.
The other connection was to provide the power,
and then we would need to plug into a power outlet
to be able to power that access point.
Today, we're providing that power over the ethernet cable
itself.
We call this Power over Ethernet, or PoE.
This means that we can run a single cable now
to our wireless access points, to our phones,
to our security cameras, and we don't
need any additional connections to be
able to power those devices.
The power that we have on a PoE connection
is often coming directly from the switch,
and you have a single run all the way to that device.
In those scenarios, we call that an endspan.
In some cases, you may need to install a device that
requires a PoE connection, but your switch
does not provide any power.
In those cases, you can put a device in the middle,
like this PoE injector, which adds power
to the ethernet connection so that you can then power
that device.
Most switches that support power over ethernet
will say it on the switch itself.
For example, this is a 10-point gigabit power
over ethernet managed switch.
Power over ethernet allows us to power device using our ethernet
cables.
Ethernet over Power, or EoP, is the reverse
of that where we are extending our ethernet
network using the power cables that we already
have in our home.
You might also hear this referred to as PLC
or Power Line Communication.
And it's an IEEE standard numbered 1901.
This EoP standard operates at 500 megabits per second,
and it's designed to connect devices that normally wouldn't
be connected to our ethernet.
Networks for example, if we had an electric car
that we recharged overnight, when we plugged it
into the power source, it would also
be connected to our ethernet network.