At least a portion of the data units in a bridge/router are processed by logic circuits according to cast type. The cast type, source address and destination address of an incoming data unit are determined by examining the header. For a unicast data unit, the source address and destination address are...http://www.google.com.au/patents/US6115379?utm_source=gb-gplus-sharePatent US6115379 - Unicast, multicast, and broadcast method and apparatus
