A minimal-buffer loss-free flow control protocol for ATM networks

Flow control is essential in ATM networks to prevent service quality degradation during periods of network congestion. In particular, best effort services such as data file transfer have stringent cell loss requirements. Use of backpressure in conjunction with buffer reservation is a promising approach. Buffer reservation on per-VC basis require large buffers. Besides, fairness and high network utilization cannot be supported at low buffer sizes. In this paper, we propose a new scheme based on buffer reservation for groups of VCs rather than for individual VCs. A general framework for credit-based link-by-link flow control is developed by disassociating buffer reser vation from credit allocation. Optirnality conditions for a credit allocation mechanism are found and an adaptive credit allocation algorithm is designed. The buffer requirement of this scheme is close to one round trip time worth of cells per group. Simulation results indicate that fairness is maintained in a robust manner.