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- [Instructor] A virtual LAN

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or VLAN is implemented primarily
to segment the network,

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but it can also be used
to reduce data collisions,

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organize the network, and
potentially boost performance,

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and possibly increase security.

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A device such as a switch
as we're showing here,

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a VLAN switch,

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will often control that
virtual local area network.

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A VLAN compartmentalizes the network,

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and it can isolate traffic.

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VLANs can be set up in a physical manner.

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An example of this would
be the port based VLAN

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where switch ports are
grouped and configured

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to act as individual VLANs.

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To do this, you would
need a managed switch.

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One that you can log into
and configure for VLAN use.

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And that's what we have here.

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We have a switch that has
connections to other switches.

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You know, you could call this
guy here a master switch,

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and he's got connections
for all these other switches

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which each go to different
areas of the building.

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Like the staff area, the
library, classroom three,

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classroom two, classroom one.

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So you can divide this
up in a physical way,

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a port based VLAN.

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There are also logical types of VLANs

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such as protocol based VLANs.

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A VLAN can be set up

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in such a way where each VLAN is

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on a different IP network.

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Like the example we're showing here

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we have classroom one on 192.168.1.0,

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classroom two is on 192.168.2,

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classroom three on .3,

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library on .4,

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and staff on 192.168.100.

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So as you can see here we
have five VLANs each connected

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to their own switches,

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and those are connected
to the master switch.

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So this could be a great way
to compartmentalize computers,

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printers, and other multifunction devices.

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In addition

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to doing port based physical
VLAN configuration here,

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we're also using IP networks.

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Or you could take it

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to the next level and
incorporate IP subnetting.

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IP subnetting is when you
divide the network into two

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or more sub networks

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by changing the subnet mask that is used.

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For example, you might be using something

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like 255.255.0.0.

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You could change that
to say 255.255.240.0.

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We're changing that third octet to 240,

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effectively taking our one IP network

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and dividing it into 16 sub networks.

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Some administrators prefer
IP subnetting over VLANs,

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and some use them together.

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For example, a group

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of physical port based
VLANs like we have here,

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each of which is on a
different IP sub network.

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Here we have them on separate IP networks.

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So it all depends on your environments.

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Let's show a switch that
has VLAN capability.

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And again, you need to make sure

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that you're working with a managed switch.

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So this is a Cisco SG200.

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And if we go to VLAN
management here and look

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at default VLAN settings,

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there's only one network right now.

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All the ports are part of one network.

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It's just one VLAN known as number one.

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But we could create
additional VLANs from here

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and add on additional VLANs.

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We could call them two and three and four

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or give them a range.

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And then we could change
the interface settings

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and specify which ports will go

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to which VLANs.

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And we could edit those ports

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and specify where
they're actually going to

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and do it by the port.

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So you don't really need to
know how to create VLANs,

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but the idea is you can
separate it by the port,

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the physical ports on the switch.

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And so this is known as a
port based VLAN for the A plus

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you don't really need to
know how to create these,

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but you should know what
it is, how they function.

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And that SG200 switch,

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there's emulators, an emulator
on Cisco's site for that

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if you wanna work with that.

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Okay. So a little bit

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about virtual local area
networks also known as VLANs.