A Virtual LAN (VLAN) is a separately administrated virtual network within the same physical network. VLANs are broadcast domains defined within switches to allow control of broadcast, multicast, unicast, and unknown unicast within a Layer 2 device.
Administrators often need to route traffic to interoperate between different VLANs. Bridge VLANs are only for non-routable traffic, like tagged VLAN frames destined to some other device which untags it. When a data frame is received on a port, the bridge VLAN determines the associated VLAN based on the port of reception. Using forwarding database information, the bridge VLAN forwards the data frame on the appropriate port(s).