Tree Pruning Optimization

RBridges may prune trees to reduce the amount of unneeded flood or multicast traffic. For example, if a leaf RBridge is not locally connected to a set of VLANs then there is no need to flood packets that contain 802.1Q tags matching those VLANs to that RBridge leaf. The set of VLANs enabled on each RBridge is communicated in the ENABLED-VLANS sub-TLV sent in the MT-PORT-CAP TLV.