Encapsulation Header S=Xmitting Rbridge D=Rcving Rbridge pt=“transit” hop count original pkt (including L2 hdr) Outer L2 hdr must not confuse bridges So it’s just like it would be if the Rbridges were routers Need special layer 2 destination address for unknown or multicast layer 2 destinations can be L2 multicast, or any L2 address provided it never gets used as a source address |