Virtual queuing: an efficient algorithm for bandwidth management in resilient packet rings

Resilient packet ring (RPR) is being devised as part of IEEE 802.17 standard, where fairness in bandwidth allocation among ring nodes, efficiency in resource utilization, and a low computational complexity are the main requirements. Although recent efforts have improved the performance of the RPR fairness algorithms to have acceptable steady-state behavior, we demonstrate that current algorithms suffer from extreme unfairness and throughput loss in some dynamic traffic scenarios. In this paper, we address the bandwidth management in RPR. First, we propose a general fairness model for packet rings. Then, a new algorithm for bandwidth management in RPR called virtual queuing (VQ) is introduced. We study the fairness properties of VQ algorithm both analytically and with simulation results. Compared to the RPR standard fairness algorithms that suffer from a throughput loss of up to 28% in some cases, the throughput loss with VQ is less than 2%. Comparing to another algorithm, called distributed virtual-time scheduling in rings (DVSR), VQ has a lower computational complexity and a better performance in a dynamic traffic environment. We show that the average throttled rate of the head node in a congestion span can be up to 80% for DVSR With VQ, it is less than 4% in all cases.