LOOKAHEAD NETWORK.

Abstract

A tree-based local-area network, called the lookahead network, is formalized and extended. The leaf nodes in the network are workstations, and the nonleaf nodes consist of pure combinational logic used in carry lookahead circuits of binary adders. Any of the ring or bus access protocols (token passing, contention, etc. ) can be used on this network. The author first gives a formal definition of the lookahead logic and shows that it can be operated in either a bus or a ring mode. The advantage of using the lookahead logic is that it makes the network operation fail-soft, and since this logic is recursively defined, it simplifies network installation, expansion, and partitioning procedures. He then defines a new round-robin access protocol on the lookahead network, which has much better throughput-delay characteristics than a token ring when the number of active nodes on the network is increased, and/or the transmission speed is increased, and/or the average packet size is decreased. Moreover, this new protocol can implement a message-based priority scheme, which makes it useful in integrated voice and data networks.