A new ATM congestion control scheme for shared buffer switch architectures

In this paper, we propose a new pre-emptive congestion control (PECC) scheme for deployment in shared buffer-based ATM networks. The proposed PECC uses a rate-based feedback scheme for dynamic bandwidth allocation to best-effort traffic coexisting with guaranteed service traffic. Policing of the guaranteed service continuous bit-rate and variable bit-rate traffic is done using the leaky bucket mechanism. The PECC is a predictive scheme rather than a reactive one. The internal state of the ATM switch is used to predict the onset of congestion. The backward explicit congestion notification feedback scheme developed in earlier works for ATM local area networks has been effectively used in our scheme for delays equivalent to those of MANs and WANs. A simulation model for an illustrative ATM network exhibiting congestion has been constructed. The effect of varying key parameters including mean inter-arrival time, buffer threshold throttle factor, cell reject throttle factor, buffer threshold, filter time and rate reduction delta has been studied. Transient behaviour of an example ATM network employing shared buffer switches under the event of congestion, and its control by backward explicit congestion notification has also been simulated.