Multicast contention resolution with single-cycle windowing using content addressable FIFO's

Abstract

Asynchronous transfer mode (ATM) has been designated as the switching environment for future broadband integrated services digital networks (BISDN) networks and services. Although input-buffered space switches are more economical and simpler to implement than output-buffered space switches, they suffer from external blocking because of destination port contention. We review contention resolution methods used to avoid external blocking, and choose a solution based on ring reservation, resulting in an elegant and efficient mechanism requiring only nearest-neighbor communications. In addition to external blocking, space switches suffer from head-of-line (HOL) blocking, and our technique alleviates HOL blocking without arbitration time overhead. This method makes use of a novel content addressable first in/first out (CAFIFO) to achieve single-cycle windowing, and the CAFIFO design and operation are described in detail. High multicast throughput is achieved by employing call-splitting. Multiple latency priorities can also be supported. Simulation results, for both unicast and multicast switching, and both random and bursty traffic, highlight the versatility and excellent performance of the CAFIFO-based switch.