What is VLAN (Virtual Local Area Network)?

A Virtual Local Area Network (VLAN) is a network segmentation technique that allows a network to be divided into multiple isolated broadcast domains. In traditional Ethernet networks, all devices within the same physical network share the same broadcast domain, which means they can communicate with each other directly. VLANs provide a way to create logically segmented networks within a physical network, even if the devices are physically connected to the same switch.

Key characteristics and features of VLANs include:

1. Isolation: Devices within a VLAN can communicate with each other as if they are on the same network, but they are isolated from devices in other VLANs. This isolation is achieved by using VLAN IDs to tag Ethernet frames.
2. Broadcast Control: Broadcast traffic is limited to the VLAN, reducing the overall broadcast domain size. This helps in optimizing network performance by preventing unnecessary broadcast traffic from affecting all devices on a network.
3. Security: VLANs enhance network security by segregating sensitive or critical data traffic from other parts of the network. Access between VLANs can be controlled using routers or layer 3 switches.
4. Flexibility: VLANs are flexible and can be created based on different criteria, such as department, project, or functional group, rather than being tied to physical locations.
5. Scalability: VLANs allow network administrators to scale and manage networks more effectively by grouping devices logically rather than relying solely on physical network infrastructure.