Integrated rate and credit feedback control for ABR service in ATM networks

Abstract

We propose a flow-control scheme that combines the merits of credit- and rate-based flow-control schemes by applying direct control over both bandwidth and buffer resources. The goal of the proposed scheme is to design an optimal rate-control policy for a given finite buffer capacity that maximizes the average throughput and bounds the end-to-end delay. By applying higher-order rate control, the proposed scheme not only makes the rate process converge to the neighborhood of the link bandwidth, but also confines the queue-length fluctuation to a regime bounded by the buffer capacity (thus guaranteeing lossless transmission). Using the fluid approximation method, we model the proposed flow-control scheme and study the system dynamic behavior for ABR (available bit rate) service under the most stressful traffic condition. We derive the expressions for queue build-ups and average throughput in both transient and equilibrium states. The analytical results have shown the proposed scheme to be stable and efficient in that the source rate and bottleneck queue length rapidly converge to the designated operating region. Also presented, are examples showing that the proposed scheme outperforms the other existing schemes.