Tradeoff between the cycle complexity and the fairness of ring networks

Abstract

In this paper we study performance tradeoffs of fairness algorithms for ring networks with spatial bandwidth reuse, by using two measures: (i) the fairness cycle size as a complexity measure; and (ii) the Max–Min optimal fairness criterion as a throughput measure. The fairness cycle size is determined by the number of communication links involved in every instance of the fairness algorithm (several identical fairness algorithms can be executed concurrently on the same ring). The study compares three fairness algorithms with different cycle sizes: the Global-cycle algorithm (implemented in the Serial Storage Architecture — SSA) in which the cycle size is equal to the number of links N in the ring; the Variable-cycle algorithm in which its cycle size changes between 1 and N links; the One-cycle, where there is a fairness cycle on every link. How the varying cycle size affects the network performance with respect to the Max–Min optimal fairness criterion is shown. The results show that for non-homogeneous traffic patterns, decreasing the fairness cycle size, while increasing the complexity, can significantly improve the performance with respect to the Max–Min optimal fairness criterion.