In this paper some performance characteristics of two media access control (MAC) protocols for local and metropolitan area networks (LANs and MANs) working in the Gbit/s range, ATMR (Asynchronous Transfer Mode Ring) and CRMA-II (Cyclic Reservation Multiple Access II), are presented. The basic access mechanisms of both protocols are described and compared. The simulation results demonstrate the major performance characteristics of the MAC protocols with one priority class under heavy load and moderate load conditions and in homogeneous and heterogeneous scenarios. Both protocols show outstanding performance characteristics for Gbit/s-LANs and offer a high utilization of the network bandwidth by destination release and global fairness by special bandwidth sharing mechanisms. Their main differences are timing characteristics like access delay, transmission delay and network latency.

Keyword Codes: C.2.2; C.2.5;C.4

Keywords: Network Protocols; Local and Metropolitan Area Networks; Performance evaluation