VLAN - Virtual Local Area Network

A VLAN is a group of devices on one or more LANs that are configured to communicate as if they were attached to the same wire, when in fact they are located on a number of different LAN segments. Because VLANs are based on logical instead of physical connections, they are extremely flexible.
VLAN is created to divided a Broadcast domain so it creates multiple broadcast domain within single switch. Basically it virtualiza the switch with different vlan's created. Broadcast domain are not basically divided by creating vlan, domain are divided when particular port are assign to different vlan. By default all the vlans are the member of Vlan 1 which is default vlan. While creating Vlan, vlan number is compulsary and you also can give a name to vlan which is optional.

The size of vlan is of 12 bit i.e (2)12 = 4096,
so the range is 0-4095, where as 0 and 4095 are reserved for voice and 1 is default Vlan.

Types of Vlan

There are 2 types of VLAN,
1. Normal Vlan (Ranges from 0-1005)
2. Extended Vlan (Ranges from 1006-4095)

Note: In Normal vlan few vlan are specifically reserved. that are,
1. 1002 - FDDI
2. 1003 - Token Ring
3. 1004 - EDDI
4. 1005 - TRNET

Creating Vlan

#Configure terminal
# vlan 10 --(Vlan number)
# name HR -- (Vlan name/optional)

# int f0/0
# switchport access vlan 10

# show vlan brief

Native Vlan

Native vlan is a vlan which has no tagging. Default native vlan is Vlan 1 but we can change it. Native Vlan must be same on all connected switch.

Note: Vlan information is stored in vlan.dat file and is in flash

By how many way we can deploy Vlan's?

There are 2 ways for vlan deployment
1. Local VLAN: Multiple vlans are created on single switch and single vlan is active then it is called local vlan deployment.

2. End to End Vlan Deployment : Multiple vlans are created on single switch and more then one vlan are active on a switch then is called end to end deployment.