A multi-color marking scheme to achieve fair bandwidth allocation

Abstract

Mechanisms for achieving fair bandwidth sharing have been a hot research topic for many years. Protection of well-behaved flows and possible simplification of end-to-end congestion control mechanisms are the ultimate challenges driving the need for research in this area. Rate-based schedulers, such as weighted fair queuing, require per-flow state information in the routers and in addition a mechanism to determine which packets to drop under congestion. Therefore they are too complex to be implemented in high-speed networks. To address this issue many other schemes have been proposed among them core stateless fair queuing (CSFQ) [1], constitutes the most revolutionary approach. In this paper we propose an edge-marking scheme that achieves fair bandwidth allocation by marking packets belonging to the same flow with different colors, i.e. layers, according to a token bucket scheme. The interior routers implement a Random Early Detection (RED) [12] based buffer acceptance mechanism that is able to drop packets based on their color. This buffer acceptance mechanism estimates the layer that is causing the congestion and drops packets according to a RED drop function. Using simulations we prove that this mechanism is stable and achieves a fair distribution of the bottleneck bandwidth.