Design of an Enhanced Fairness Algorithm for the IEEE 802.17 Resilient Packet Ring

The fairness algorithm of the Resilient Packet Ring IEEE 802.17 standard suffers from throughput degradation under an unbalanced overload. This paper designs an enhanced aggressive mode of fairness algorithm to resolve this throughput degradation and discusses its performance. Under the enhanced aggressive mode, upstream nodes set their allow_rates as their maximum values when a congested node advertises congestion alleviation to them. The congested node decides its congestion alleviation once its STQ length goes below a threshold. A new fairness packet of type 3 is used for the congestion alleviation advertisement.