Fair and flexible contention resolution for input buffered ATM switches based on LAN medium access control protocols

Only switches with input buffers offer the possibility to handle effectively the large and full-rate bursts that arise from the transport of data traffic and the burst accumulation within large ATM networks. Efficient contention resolution mechanisms are necessary to prevent output blocking in these input buffered switch architectures and to allow a fair and waste-free utilization of the switch. This paper first reviews the different types of existing contention resolution mechanisms and shows their limits concerning fairness, scalability, and the possibility to support switching of multicast and prioritized cell streams. Then a new approach is presented that achieves an absolutely fair and efficient contention resolution on the cell level by using modified LAN medium access control (MAC) protocols. The requirements that a MAC protocol has to accomplish are investigated and the excellent performance (using an adapted version of the CRMA-II MAC protocol) of the proposed approach is shown. Finally native extensions toward the integration of multicast and prioritized traffic are given and it is demonstrated how this architecture can easily be scaled up to coordinate switches with throughputs of several Terabits per second.