What is a VLAN and How to Configure VLANs

What is a VLAN

VLANs (Virtual Local Area Networks) are used to separate the large broadcast domains into smaller ones to improve the network performance. Although only one VLAN is configured on the switch out of the box, normally two or more VLANs a switch have to be configured. Doing so puts some interfaces into one VLAN to create multiple broadcast domains and puts other interfaces into other VLANs.

The reason for using the VLANs

v Instead of physical location, grouping the users by the department.
v Segmenting devices reduce overhead processing into smaller LANs for all devices on the LAN.
v Reducing the STP workload by adding a limit on VLAN to a single access switch.
v Isolating sensitive data to separate VLANs to enforce better security.
v Separate data traffic and IP voice traffic.

Benefits of using the VLANs

v Security: In one VLAN the sensitive data can be isolated and separating it from the rest of the network
v Cost reduction: Cost savings result from less need for expensive network upgrades and more existing bandwidth and uplinks for efficient use.
v Higher performance: Dividing the network layer 2 into multiple logical broadcast domains and on the network reduces unnecessary traffic and boosts performance.
v Broadcast storm mitigation: a broadcast storm is prevented by segmenting the VLAN from propagating throughout the entire network.
v Ease of troubleshooting and management: Network addresses are grouped through a hierarchical IP addressing scheme contiguously. Because problem components are easier to locate through the hierarchical IP addressing scheme, network troubleshooting, and network management are more efficient.