Before taking deep down to the VLAN lets start with the definition. Virtual Local Area Network or Virtual LAN. As the name suggests, it is a virtual network of a logical subnetwork that groups a collection of devices from different physical LANs. It maps devices on a basis other than geographic location. Traffic that flows between different VLANs must go through a router, just as if the VLANs are on two separate LANs.
In technical term, VLAN means a broadcast domain created by switches. Normally, it is a router creating that broadcast domain but with VLANs, a switch can create the broadcast domain. VLAN extends beyond a single traditional LAN to a group of LAN segments, given specific configurations. And since a VLAN is a logical object, its creation and configuration are completely done on software.
To define a VLAN on a Cisco device, you need to have a valid VLAN ID, a VLAN name, ports that would participate in VLAN and the type of membership the designated port will have with VLAN.
Benefits of using VLAN
- VLANs let you subdivide your network easily
- By efficiently using network bandwidth, VLAN can achieve as many logical networks to use the same network infrastructure. It forms a virtual workgroup for effective communication between members and workgroup.
- VLAN decreases the number of users of routers needed since VLANs create broadcast domains using switches instead of routers. Less router, less configuration.
- VLANs are easy to manage
- When you create a subdivision of a large network, it would be much easier for troubleshooting of problems within the network.
- It simplifies the process by logically assigning the groups into the same virtual network to make it easy to set up and control the policies at the group level.
- VLANs provide increased performance
- VLAN segments the network into distinct broadcast groups. And since the broadcast traffic resides in only one VLAN, this type of connection subsequently reduces overall broadcast traffic hence freeing bandwidth for the real user, and also significantly minimizes the overall vulnerability of the network to broadcast storms.
- VLANs increase network security
- By reducing both internal and external threats, VLAN improves security and privacy by ensuring only authorised user can access the networks to their responsibilities.
- IT creates a directory that the only router can access which means VLAN will restrict access to any non-router activity.
- Reduced network administration cost associated with the moving, adding and changing
- For a large organization, they have to frequently reorganize things to improve productivity. Those moving, adding and changing process could be cost expensive for a company. For that reason, VLANs provide an effective mechanism to control these changes and reduce much of the cost configuration.
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