IEEE 802.1Q

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Categories: Standards

IEEE 802.1Q is the networking standard that supports virtual LANs (Local Area Networks) (VLANs) on an Ethernet network. The standard defines a system of VLAN tagging for Ethernet frames and the accompanying procedures to be used by bridges and switches in handling such frames.

It allows several VLANS to be carried across one network link between switches (between ‘Tagged Ports’ or ‘Trunk Ports’). Ports where 802.1Q tagging is turned off are usually known as ‘Access Ports’. Most computers don’t understand the VLAN tag, so shouldn’t be plugged into Trunk Ports.

The standard also contains provisions for a quality of service prioritization scheme commonly known as IEEE 802.1p.

See CoS, VLAN