VLAN stands for virtual LAN and technically we can say, a VLAN is a broadcast domain created by switch. When managing a switch, the management domain is always VLAN 1, the default VLAN. All ports of switch are assigned to VLAN 1 by default. VLAN increase the performance of a network because it divide a network logically in different parts and limit the broadcasts.
Any member of VLAN 2 can not talk with any member of VLAN 3 without router but all the members of VLAN 2 and VLAN 3 can talk with other members within their VLANs.
This Lab will also help how VLANs can be used to separate traffic and reduce broadcast domains.
To create a VLAN, first enter global configuration mode to run the following commands.
Configuration to create VLAN 2
SwitchA(config)#configure terminal (enter in global configuration mode)
SwitchA(config)#vlan 2 (defining the vlan 2)
SwitchA(config)#vlan 2 name marketing (assigning the name marketing to vlan 2)
SwitchA(config)#exit (exit from vlan 2)

Configuration to create VLAN 3
SwitchA(config)#configure terminal (enter in global configuration mode)
SwitchA(config)#vlan 3 (defining the vlan 3)
SwitchA(config)#vlan 3 name management (assigning the name management to vlan 3)
SwitchA(config)#exit (exit from vlan 3)
Now assigning the ports 2 and 3 to VLAN 2, it must be done from the interface mode. Enter the following commands to add port 2 and 3 to VLAN 2.
SwitchA(config)#configure terminal (enter in global configuration mode)
SwitchA(config)#interface fastethernet 0/2 (select the Ethernet 0 of port 2)
SwitchA(config-if)#switchport access vlan 2 (allot the membership of vlan 2)
SwitchA(config-if)#exit (exit from interface 2)

Now adding port 3 to VLAN 2
SwitchA(config)#interface fastethernet 0/3 (select the Ethernet 0 of port 3)
SwitchA(config-if)#switchport access vlan 2 (allot the membership of vlan 2)
SwitchA(config-if)#exit (exit from interface 3)

Now assigning the ports 4 and 5 to VLAN 3, enter the following commands to add port 4 and 5 to VLAN 3.
SwitchA(config)#configure terminal (enter in global configuration mode)
SwitchA(config)#interface fastethernet 0/4 (select the Ethernet 0 of port 4)
SwitchA(config-if)#switchport access vlan 3 (allot the membership of vlan 3)
SwitchA(config-if)#exit (exit from interface 4)

Now adding port 5 to VLAN 3
SwitchA(config)#interface fastethernet 0/5 (select the Ethernet 0 of port 5)
SwitchA(config-if)#switchport access vlan 3 (allot the membership of vlan 3)
SwitchA(config-if)#exit (exit from interface 5)
To show the VLAN interface information, run the command show vlan.



Source:computeronlinetips.com