Dynamic rate control for supporting ABR service in ATM networks

For supporting the available bit rate (ABR) service in ATM networks, existing feedback-based rate control schemes mostly employ a single static buffer threshold at each switching node as the forewarning of congestion. We first propose a continuous-based adaptive rate control mechanism which employs, logically, an infinite number of thresholds. The scheme achieves high link utilization and low (zero) cell loss ratio under highly bursty (deterministic) traffic, though at the expense of a high signaling overhead due to frequent adjustment of permitted rates. To reduce overhead, we further propose the stepwise-based rate control mechanism adopting a limited number of movable thresholds adapting to changes in departure rates. Compared to continuous-based control via simulation, stepwise-based control is shown to be efficient and accurate using only a reasonably low number of thresholds. Moreover, simulation results demonstrate that the stepwise-based mechanism outperforms existing schemes with respect to cell loss ratio and link utilization.