QUEUING DISCIPLINES AND PASSIVE CONGESTION CONTROL IN BYTE-STREAM NETWORKS

This paper deals with queueing disciplines for a class of wide-area virtual-circuit data networks. Messages on each virtual circuit are transmitted logically as streams of bytes. A small number of successive bytes are collected into a packet and provided with an address header. Packets from different virtual circuits are intermingled on trunks and are relayed from one node of the network to another, while protocol processing and flow control are handled at the network edges. We compare the performance of first-in-first-out and round-robin packet service disciplines at the trunk nodes, including, if desired, priority service for single-packet messages. We survey the delay and throughput characteristics of the different disciplines as a function of traffic mix, packet size, traffic intensity, and the ratio of trunk speed to access line speed. Exact and approximate analyses are compared with the results of simulations. Under normal traffic conditions, most disciplines will give acceptable mean delay if the ratio of trunk speed to access line speed is sufficiently high. Round-robin disciplines have better fairness properties than first-in-first-out disciplines when the network is congested, in that they protect well-behaved users against the demands of uncontrolled users.