This paper provides a comparative evaluation of the performance of ring and bus systems constituting subnetworks of local-area networks. Performance is measured in terms of the delay-throughput characteristics. Systems investigated include token-controlled and slotted rings as well as random-access buses (CSMA with collision detection) and ordered-access buses. The investigation is based on analytic models which describe the various topologies and access mechanisms to a sufficient level of detail. The paper includes a comprehensive discussion of how the performance of the different networks is affected by system parameters like transmission rate, cable length, packet lengths, and control overhead. Copyright © 1981 by The Institute of Electrical and Electronics Engineers, Inc.