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
Read: How do switch works ?
VLAN video source Kevin Wellace: https://www.youtube.com/watch?v=DfnooO3J8i4
VLAN is a logical group of end devices independent of their physical location . VLAN is a broadcast domain(collection of devices under one network).
Consider the scenario where a company CCNPexperts has 2 floors and each floor with 2 departments Acct. and Sales .Our aim is to develop networks for both the departments say (10.0.0.0) for Acct. and (20.0.0.0) for Sales. we can configure network in switch, but here exist 2 different networks, and a switch can have only one network. What do we do now ?
We can split the switch into 2 virtual LAN (VLAN) so that we can divide the single broadcast domain into 2 broadcast domain and assign network for different broadcast domains (VLANs).
Properties of VLAN
- Flexibility of design based on function or department.
- Enhanced security
- By default all ports are assigned toVLAN 1 known as administrative VLAN or Management VLAN.
- Ethernet VLANs can be created from 2-1001.
- Membership can be static or dynamic.
VLAN Configuration
To see VLANs
switch# enable
switch# show vlan
By default we have only a single VLAN , all ports are assigned to this particular VLAN 1.
VLANs 1002, 1002 ,1004 , 1005 cannot be used.
To create Vlan
switch(config)# vlan 100
switch(config-if)# name Sales
switch(config-if)# exit
To add ports to VLAN
switch(config)# interface range Gi 1/0/3 -4 /* Gi for Gigabite cable-1000 Mb/s and Fa for FastEthernet-100 Mb/s*/
switch(config-if)# switchport mode access
switch(config-if)# switchport access VLAN 100
switch(config-if)# exit
Now you can see a new VLAN 100 is created with name Sales
How can we connect multiple VLANs through a single channel ?
Trunking watch here
CCNPexperts 