[Instructor] By default, a switch has all of its ports
in a single broadcast domain.
This means if a broadcast is sent,
it will go out to all ports
save for the one it entered on.
Following that logic, to create separate broadcast domains,
an engineer would have to use a different switch
for each domain,
which isn't practical or scalable in any real way.
This is where Virtual LANs or VLANs come in.
VLANs allow logical segmentation within a single switch.
A VLAN allows for multiple separate broadcast domains
to exist in the same switched infrastructure.
VLANs have many benefits.
They reduce the number of devices
that needlessly receive broadcasts.
They increase security by segregating networks,
and they also shrink the failure domain
so troubleshooting issues can be simpler.
Manage switches, or those that allow VLAN configuration,
generally default to having all ports configured
for the default VLAN.
In Cisco Kit this will be VLAN 1.
As a best practice, all ports should be moved
to a VLAN other than 1.
Being the default VLAN,
an administrator can't delete VLAN 1.
A VLAN is created from global configuration mode
by specifying the VLAN ID.
In this example, I'll configure VLAN 10.
Config t, VLAN 10.
The VLAN has technically been created and can be used,
but best practice is
to give each VLAN a useful name, like name user-data.
I'll also create a VLAN for VoIP traffic.
VLAN 11, name user-voip.
Now that the VLANs have been created,
I'll assign them to some user ports.
In this example I'll configure ports one and two
at the same time using the interface range command.
Interface range fa0/1 to 2.
By default, every switchboard is configured as dynamic auto.
This means it will try and automatically determine
what the port at the far end
would like the mode to be adjusted to.
I don't like surprises in my network,
so I always adjust port modes to be accessed.
This is done with switch port mode access.
An access port is what a standard device is connected to,
something like a PC, printer, router.
In essence, an end device.
The access designation tells the switch
to strip the VLAN tag off of a packet as it leaves this port
and to place it back on as it enters.
VLAN tags are actually placed in the frame header
using various different standards,
but the one the CCNA focuses on,
and most switches use, is 802.1Q.
A tag is just a number that represents
how the VLAN is identified inside the switch.
The VLAN tag for my user ports will be 10,
as that's what I've configured for user data.
The access VLAN is assigned to a port
with the switch port access VLAN 10 command.
Now all frames entering and exiting these ports
will only traverse VLAN 10.
I'm going to clear this screen for clarity.
I can verify active access ports and configured VLANs
with the show VLAN command.
Cisco also has a special configuration option
for the VoIP solutions called Voice VLAN.
This allows a port to have an additional VLAN added to it
so that if a Cisco phone is connected to the port,
it will automatically have the phone traffic moved
to the special Voice VLAN.
This command is actually pretty easy to implement.
Config t, interface range fa0/1 to 2,
and the special command switch port Voice VLAN 11.
Now any of my Cisco VoIP Kit
will automatically be segregated from regular user data.
I've utilized VLANs in every network I've ever built,
so it's no surprise that
it will be heavily covered on the test.