- [Instructor] A virtual LAN
or VLAN is implemented primarily to segment the network,
but it can also be used to reduce data collisions,
organize the network, and potentially boost performance,
and possibly increase security.
A device such as a switch as we're showing here,
a VLAN switch,
will often control that virtual local area network.
A VLAN compartmentalizes the network,
and it can isolate traffic.
VLANs can be set up in a physical manner.
An example of this would be the port based VLAN
where switch ports are grouped and configured
to act as individual VLANs.
To do this, you would need a managed switch.
One that you can log into and configure for VLAN use.
And that's what we have here.
We have a switch that has connections to other switches.
You know, you could call this guy here a master switch,
and he's got connections for all these other switches
which each go to different areas of the building.
Like the staff area, the library, classroom three,
classroom two, classroom one.
So you can divide this up in a physical way,
a port based VLAN.
There are also logical types of VLANs
such as protocol based VLANs.
A VLAN can be set up
in such a way where each VLAN is
on a different IP network.
Like the example we're showing here
we have classroom one on 192.168.1.0,
classroom two is on 192.168.2,
classroom three on .3,
library on .4,
and staff on 192.168.100.
So as you can see here we have five VLANs each connected
to their own switches,
and those are connected to the master switch.
So this could be a great way to compartmentalize computers,
printers, and other multifunction devices.
In addition
to doing port based physical VLAN configuration here,
we're also using IP networks.
Or you could take it
to the next level and incorporate IP subnetting.
IP subnetting is when you divide the network into two
or more sub networks
by changing the subnet mask that is used.
For example, you might be using something
like 255.255.0.0.
You could change that to say 255.255.240.0.
We're changing that third octet to 240,
effectively taking our one IP network
and dividing it into 16 sub networks.
Some administrators prefer IP subnetting over VLANs,
and some use them together.
For example, a group
of physical port based VLANs like we have here,
each of which is on a different IP sub network.
Here we have them on separate IP networks.
So it all depends on your environments.
Let's show a switch that has VLAN capability.
And again, you need to make sure
that you're working with a managed switch.
So this is a Cisco SG200.
And if we go to VLAN management here and look
at default VLAN settings,
there's only one network right now.
All the ports are part of one network.
It's just one VLAN known as number one.
But we could create additional VLANs from here
and add on additional VLANs.
We could call them two and three and four
or give them a range.
And then we could change the interface settings
and specify which ports will go
to which VLANs.
And we could edit those ports
and specify where they're actually going to
and do it by the port.
So you don't really need to know how to create VLANs,
but the idea is you can separate it by the port,
the physical ports on the switch.
And so this is known as a port based VLAN for the A plus
you don't really need to know how to create these,
but you should know what it is, how they function.
And that SG200 switch,
there's emulators, an emulator on Cisco's site for that
if you wanna work with that.
Okay. So a little bit
about virtual local area networks also known as VLANs.