Patent ID: 7877483

Claim:
A method comprising: generating, by a VLAN pruning logic of an intermediate network device within a computer network, one or more control packets that include device-local Virtual Local Area Network (VLAN) membership information for the intermediate network device, the device-local VLAN membership information indicating one or more VLANs specifically configured on access ports of the intermediate network device, the device-local VLAN membership information excluding VLAN membership information learned from other intermediate network devices in the computer network that may be reachable through the intermediate network device; flooding the one or more control packets on one or more trunk ports of the intermediate network device to distribute control packets that includes the device-local VLAN membership information throughout the computer network; transitioning a given trunk port of the intermediate network device to a forwarding spanning tree port state for a given VLAN, to define an active topology within the computer network; maintaining a current wanted data structure, the current wanted data structure indicating whether intermediate network devices, accessible via the given trunk port that is in the forwarding spanning tree port state for the given VLAN, have access ports that are associated with the given VLAN, and thereby whether messages associated with given VLAN should be forwarded over the given trunk port that is in the forwarding spanning tree port state for the given VLAN; and preventing transmission of a message, associated with the given VLAN, over the given trunk port that is in the forwarding spanning tree port state for the given VLAN, unless the current wanted data structure indicates that there are intermediate network devices accessible via the given trunk port that have access ports that are associated with the given VLAN and thereby that messages associated with given VLAN should be forwarded over the given trunk port.