Cell multiplexing in ATM networks

Abstract

In this paper, we formulate, analyze, and compare among several connection multiplexing algorithms for a multiplexer residing in the equivalent terminal of the asynchronous transfer mode (ATM) layer at the user premise. The primary goal is to find an algorithm that efficiently combats the cell delay variation (CDV) introduced by the multiplexer. Several performance criteria are examined, one of which is unique to ATM networks. This one is the proportion of arriving cells that do not conform to the traffic contract of the connection. The conformance is being tracked by a generic cell rate algorithm (GCRA) recommended (but not mandatory) by CCITT. Other criteria are the classical buffer requirements and the cell delay. Service fairness among connections is also evaluated with respect to each performance criterion. The impact of the following five multiplexing policies on the performance criteria are evaluated for constant bit rate (CBR) traffic sources. The policies are first in, first out (FIFO), round robin (RR), least time to reach bound (LTRB), most behind expected arrival (MBEA), and golden ratio (GR). Extensive numerical examples reveal that there is no single policy that is best across all criteria. With respect to cell conformance, most behind expected arrival (MBEA) emerges as the preferred one. FIFO is best with respect to cell delay, except for high utilizations where RR dominates. The LTRB is marginally better than all other policies with respect to buffer requirements. © 1996 IEEE.