Design of Effective Buffer Control Policies for ATM Networks

Due to limited buffers and highly unpredictable traffic loads, the design of effective buffer management policies that minimize cell loss is critical to ATM networks. We outline the important characteristics of optimal buffer control policies for a single node, and using a dynamic programming formulation for a simple two-node network, gain insights into the much harder general multi-node problem. The key result we present is that simple non-workconserving policies which use limited feedback from adjacent nodes can reduce cell loss significantly. We construct a feedback-based control that uses simple “stop-and-go” rules. This control is then enhanced to react to rapidly changing network conditions. This new control is called the Adaptive HILO policy. Simulation studies of complex networks with large delay-bandwidth product show that the Adaptive HILO policy performs impressively under diverse conditions. Using intuitive arguments, we demonstrate that this policy effectively utilizes unused buffer capacity in upstream buffers during periods of heavy load in downstream buffers.