An Approach towards End-to-end QoS with Statistical Multiplexing in ATM Networks

We address the problem of providing quality-of-service (QoS) guarantees in a multiple hop packet/cell switched environment while providing high link utilization in the presence of bursty tra c. A scheme based on bandwidth and bu er reservations at the Virtual Path level is proposed for ATM networks. This approach enables us to provide accurate end-to-end QoS guarantees while achieving high utilization by employing statistical multiplexing and tra c shaping of bursty tra c sources. A simple round robin scheduler is proposed for realizing this approach and is shown to be implementable using standard ATM hardware viz. cell spacers. The problem of distributing the bandwidth and bu er space assigned to a VP over its multiple hops is addressed. We prove the optimality of the approach of allowing all the end-to-end loss to occur at the rst hop under some conditions and show that its performance can be bounded with respect to the optimal in other conditions. This results in an equal amount of bandwidth to a VP at each hop and essentially no queueing after the rst hop. Using simulations, the average case performance of this approach is also found to be good. Additional simulation results are presented to evaluate the proposed approach.