Introduction to VLAN

VLAN, the abbreviation for Virtual Local Area Network, is defined in IEEE 802.1Q. VLAN has the following features:

• A physical LAN can be divided into multiple VLANs, and a VLAN might include devices from multiple physical networks.
  
• A VLAN is virtually a broadcast domain. Layer 2 packets between VLANs are isolated. Communications between VLANs can only be implemented by Layer 3 route technique (through routers, Layer 3 switches or other Layer 3 network devices).

VLANs are differentiated by VLAN numbers. The value range is 1 to 4094. The system reserves 32 VLAN numbers (224 to 255) for BGroup, but the unused numbers within the range are also available to VLANs.