VLAN is defined as a virtual local area network. Virtual that means not physically present, but separate logically.
To understand VLAN first we discuss two concepts
- A Broad cast domain
- A Collision Domain
Generally,Domain is a group of devices which share data.Each domain is separated from other domain.
Broadcast domain is a logical division computer network in which all nodes can reach each other by broadcast at data link layer.It might present in the same LAN or it bridge to other LAN.
Collision Domain is a section of the network connected with shared medium where data can collide with one another.
what is VLAN ?
VLAN concept is used in switch because SWITCH divides collision domain, but not broadcast domain. Below the figure is shows working off switch without VLAN.
By default ,all ports on a switch are in the same broadcast domain.
A virtual local area network or VLAN ,can be used to divide a single broadcast domain to multiple broadcast domains in the layer 2 switched network.
What is the need of VLAN ?
1. Performance
In network traffic consist of broadcast and multicast,VLAN can reduce limited that traffic to reach unnecessary destination.
2. Generating virtual group
Now a day people are working in cross functional teams with members of different departments.This people are working together for a particular(limited or short) period of time. Despite of their physical location they belong to one group.
3. Simplified Administration
Maximum cost of computer network is because of adding,movement and changes of users.Some of the tasks are becoming easier.
4. Reduce cost
Due to division of broadcast domain traffic reduce and the need of expensive routers is eliminated.
5. Security
Sensitive data may be broadcast before VLAN. By introducing VLAN that data only access by a group of members who belongs to VLAN.
Example : In First Figure All nodes belong to One broadcast domain like in public when a politician is giving a speech and everyone is listening.
In second figure we divide that broadcast domain in to VLAN so now it's like radio broadcast who want to listen to a particular station that can listen only that station.
but in the case of VLAN those who belong to particular VLAN can get that broadcast packet.It increases security because no one else can get that data.
what is VLAN ?
VLAN concept is used in switch because SWITCH divides collision domain, but not broadcast domain. Below the figure is shows working off switch without VLAN.
A virtual local area network or VLAN ,can be used to divide a single broadcast domain to multiple broadcast domains in the layer 2 switched network.
What is the need of VLAN ?
1. Performance
In network traffic consist of broadcast and multicast,VLAN can reduce limited that traffic to reach unnecessary destination.
2. Generating virtual group
Now a day people are working in cross functional teams with members of different departments.This people are working together for a particular(limited or short) period of time. Despite of their physical location they belong to one group.
3. Simplified Administration
Maximum cost of computer network is because of adding,movement and changes of users.Some of the tasks are becoming easier.
4. Reduce cost
Due to division of broadcast domain traffic reduce and the need of expensive routers is eliminated.
5. Security
Sensitive data may be broadcast before VLAN. By introducing VLAN that data only access by a group of members who belongs to VLAN.
In second figure we divide that broadcast domain in to VLAN so now it's like radio broadcast who want to listen to a particular station that can listen only that station.
but in the case of VLAN those who belong to particular VLAN can get that broadcast packet.It increases security because no one else can get that data.
