ABR Service in ATM Networks: Performance Comparison Between BECN and Adaptive Stochastic Congestion Control Schemes with Guaranteed Minimum Cell Rate

Abstract

Two rate-based feedback schemes for congestion control in ATM networks: Backward Explicit Congestion Notification (BECN) and proposed Adaptive Stochastic (AS) are compared under heavy load conditions. Neither of the schemes dictates a particular switch architecture. The requirements tested include: utilization, queuing delay, queuing delay variance and queue size. The controllable sources’ allowed cell rates (ACR) have been dynamically shaped by the feedback messages based on the instantaneous queue size in the ATM switch output buffer. The results of a simulation study are presented which suggest that AS scheme, while retaining practically the same link utilization, can provide for higher priority traffic considerably shorter average queuing delay, queuing delay variance, maximum and average queue size in the switch output buffer, particularly on longer network segments between terminals generating traffic and the switch.