Research On Fair Bandwidth Allocation Mechanism For Resilient Packet Ring

IEEE is currently standardizing a new full-duplex spatial reuse ring network architecture, called the Resilient Packet Ring (RPR, IEEE P802.17). The reliability of SDH ring, high-efficiency and economy of Ethernet are integrated into this technology. It is an important trend for the evolvement of MANs.A key performance objective of RPR is to simultaneously achieve high utilization,spatial reuse,and fairness.The core technical challenge for RPR is the design of a bandwidth allocation algorithm that dynamically achieves these three properties.At first, this paper introduces the characteristics of RPR. On the basis of which,frame format, topology discovery and protection switching schemes are elementarily discussed. Emphasis of our research is put on fair bandwidth management scheme of RPR. The research work follows two steps:firstly, we base on the draft fairness algorithm of the RPR ,study the basic theory of RPR fairness algorithm, and discuss the factors that influence the performance of fairness algorithm. A fairness reference model based on RPR-RIAS was introduced. We analyze the mathematic model of RIAS, and discuss the difference between RIAS and other model.Secondly, based on RIAS,a new algorithm-DVSR (Distributed Virtual-time Scheduling in Rings) is provided, which greatly resolves the phenomena of continual bandwidth oscillations with unbalanced and constant-rate trafic demand scenario in current drafts. We improve the algorithm.Finally, by the means of computer, the performance of DVSR algorithm is simulated, the results show DVSR algorithm has better performance.