A packet communications system provides for point-to-point packet routing and multicast packet routing to limited subsets of nodes in the network, using a routing field in the packet header which is processed according to two different protocols. A third protocol is provided in which a packet can be...http://www.google.com.au/patents/US5309433?utm_source=gb-gplus-sharePatent US5309433 - Methods and apparatus for routing packets in packet transmission networks
