Preventing internal and external conflicts in an input buffering reverse baseline ATM switch

Abstract

When two or more packets that are destined to the same output of an ATM switch arrive at different inputs, buffers at inputs or outputs are used to queue all but one of these packets so that external conflict is prevented. Although input buffering ATM switches are more economical and simpler than output buffering ATM switches, significant loss of throughput can occur in input buffering ATM switches due to head-of-line (HOL) blocking when first-in–first-out (FIFO) queueing is employed. In order to avoid both external conflict and alleviate HOL blocking in non-blocking ATM switches, some window-based contention resolution algorithms were proposed in the literature. In this paper, we propose a window-based contention resolution algorithm for a blocking ATM switch based on reverse baseline network with content addressable FIFO (CAFIFO) input buffers. The proposed algorithm prevents not only external conflicts but also internal conflicts, in addition to alleviating HOL blocking. This algorithm was obtained by adapting the ring reservation algorithm used on non-blocking ATM switches to a reverse baseline network. The fact that a non-blocking network is replaced by a log2 N-stage reverse baseline network yields a significant economy in implementation. We have conducted extensive simulations to evaluate the performance of reverse baseline network using the proposed window-based contention resolution algorithm. Simulation results show that the throughput of reverse baseline network can be as good as the throughput of non-blocking switches if the window depth of input buffers is made sufficiently large. Copyright © 2000 John Wiley & Sons, Ltd.