The token-skipping channel access scheme for bus networks

Abstract A major disadvantage of the standard token-bus network architecture is the delay involved in passing the token through idle stations. A modified token-passing scheme is described that minimizes this overhead by bypassing idle stations. This scheme requires very little additional hardware over the proposed IEEE 802.4 channel-access protocol and has this proposed standard protocol as one of its limiting cases. Simulation studies of this scheme show significant improvement of delay-throughput characteristics for practical load ranges. For example, for throughputs up to about 65%, a network with 100 nodes with Poisson arrivals and symmetric load distribution among nodes has a mean delay of less than half that of a similar network using the conventional token-passing scheme. Under asymmetric load distribution among nodes, even higher speedup factors can be achieved.