Weighted Fair Early Packet Discard at an ATM Switch Output Port

In this paper we consider an output port of an ATM switch, where cell streams belonging to different TCP and UDP sessions arrive. During congestion the switch applies Early Packet Discard in order to reduce bandwidth waste. In order to guarantee fairness in the sense that only misbehaving sources get affected by the packet drop mechanism and to ensure high server utilization we propose an algorithm which also features simplicity. A salient feature of this algorithm is that it allows a predefined share i to be associated with stream i. The algorithm (which we call the Weighted Fair EPD, WFEPD) attempts to provide this weighted share of the bandwidth for the streams in the long time average. A sliding window implementation of WFEPD allows us to demonstrate its efficiency in terms of fairness and bandwidth utilization.