Abstract
The Resilient Packet Ring (IEEE 802.17) fairness algorithm is simple, but exhibits some weaknesses. The bandwidth allocation severely oscillates when the traffic is unbalanced. Several algorithms have been proposed in recent years to overcome this issue. For example, the proportional controller is used for solving the fairness problem. The proportional controller is able to converge to the fair rates with no oscillations at the steady state. Unfortunately, the controller shows bandwidth oscillations and becomes unstable if the network delay is significant. In this paper, the impact of the delay is studied analytically and through simulation. Also, the Smith’s principle is used to compensate the ring delay. Moreover, the controller gain is tuned using a fuzzy logic system. The performance is evaluated through simulation and the results show that the proposed adaptive predictive proportional controller assures fairness, stability and high bandwidth utilization even in ring network with large delay.
Highlights
The current technologies for metro access ring network have several limitations
SIMULATION RESULTS The Simula Resilient Packet Ring Network (RPR) simulator is used for evaluating the fairness algorithms [37]
Flow(5, 6) gets its rate of 50Mbps and Flow(1, 6) gets the rest of the available resources and sends data at rate of 572Mbps with no oscillations. This proves the advantage of the adaptive predictive proportional controller to dynamically tune the controller gain and eliminate the delay impact
Summary
The current technologies for metro access ring network have several limitations. For example, SONET ring assures fast protection at the expense of resource utilization where 50% of the available resources is reserved for protection. Gigabit Ethernet assures high bandwidth utilization at the expense of fairness and fast recovery from a failure. The Resilient Packet Ring Network (RPR) [1], [2] is described in the IEEE 802.17 as the integration of SONET and Ethernet advantages. It assures cost effectiveness, fast ring recovery, high utilization and fairness. The RPR technology supports the spatial reuse feature that enables deferent segment of the ring to carry deferent data traffic simultaneously for high bandwidth utilization. The remaining bandwidth is for the best effort traffic and it is important to assure fairness.
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