Each switch in a switch cluster is implemented as two logical switches—a logical UNI switch and a logical NNI switch implementing a Backbone Edge Bridge (BEB). The logical UNI switch handles forwarding to UNI receivers. The logical NNI switches are treated as independent switches by the SPB control plane and handle forwarding to NNI receivers. The two logical switches exchange packets through UNI/NNI and NNI/UNI translations (Mac-in-MAC encapsulation/decapsulation). The Inter-Switch Trunk is viewed as two logical channels—a UNI logical channel and an NNI logical channel. The logical UNI switch will forward packets having NNI receivers to the logical NNI switch. The logical NNI switch will forward packets having UNI receivers to the logical UNI switch only if the packet has a B-VID matching a B-VID assigned to the node of the switch cluster.