Virtual LAN defined by set of ports on [one or more trunked] switch[es].
Vlan == broadcast domain == subnet == IP network
Using one or more switches, can put different departments on different Vlans.
Or, a Vlan for network management, one for internal, one for Guest.
End systems are oblivious of Vlan; they only know what IP network (subnet) they are in.
Trunk link between switches tags frames with 802.1Q 4B Vlan# header, 12 bits of which is VLAN ID.
Create a Vlan in global config: vlan N
Assign interface to a Vlan. in int config:
switchport access vlan N switchport mode access
show vlan
