VLAN (Virtual LAN)

A VLAN (Virtual Local Area Network) splits one physical switch network into several separate logical networks. Devices in different VLANs cannot talk directly even when they plug into the same switch; traffic between VLANs must pass through a router or layer-3 switch, where it can be filtered.

VLANs are used to separate departments, guest Wi-Fi, servers, IP phones and cameras, which improves security and reduces broadcast traffic. Each VLAN has a number (ID), and links between switches carry several VLANs at once as trunks, tagging each frame with its VLAN ID (IEEE 802.1Q).