Virtual LANs
Virtual LANs also known as VLAN, is a concept in which we can divide the devices logically into 2 data link layers. The broadcast domain can be divided by switches using the concept of VLAN. A broadcast domain is a segment of the network in which if any device broadcasts a packet, then all the devices in the same domain will receive it. But it is limited to switches and to forward out the broadcast packets to different VLAN, inter VLAN routing is required.
Configuration:
VLANs can be created by simply assigning the VLAN-id and VLAN names.
For eg. : #switch1(config)#vlan 2
#switch1(config-VLAN)#vlan accounts
2 is the VLAN-id and accounts is the VLAN name. Then VLAN is assigned to the switch ports.
For eg: Switch(config) #int fa0/0
Switch(config-if) #switchport mode access
Switch(config-if) #switchport access VLAN 2
The switch port range can be also assigned.
For eg: Switch(config) #int range fa0/0-2
Switch(config-if) #switchport mode access
Switch(config-if) #switchport access VLAN 2
Advantages:
The advantages of VLANs are as follows:
- VLAN reduces the need to send traffic to unnecessary destinations.
- It helps to group the devices logically according to their departments.
- They are useful to inform the network manager of an intrusion.
- It provides the flexibility to add and remove the number of hosts we want.
- VLANs can be used to create broadcast domains that can help eliminate the need for expensive routers.
- VLANs can help increase the number of small size broadcast domains that are easier to handle than a bigger broadcast domain.
Virtual LANs