基于累积效应的光交换机分组调度算法

光交换机中的光路重置需要较长的时间,分组调度必须是基于帧的.为提高传输效率帧长通常较大,从而导致了光交换机中特有的分组累积效应.针对该效应,提出一种新的分组调度算法p-LQF(Longest Queue First)+Hold.通过对业务需求矩阵分解得到置换矩阵, 选择匹配占用最大的置换矩阵建立端口匹配.在4×4端口的VOQ(Virtual Output Queue)结构的光交换机中,分别对均匀、非均匀以及对角线的Bernoulli和ON/OFF业务进行了仿真.仿真结果显示该算法对于符合强大数定理的可接入业务能获得100%的通过率,其平均分组时延接近甚至低于主流的LQF+Hold算法,但复杂度更低.该算法能够提供带宽保证以及短期公平性,同时能适应分组的动态到达. 

Novel scheduling algorithm based on packet aggregation effect for optical switches

The packet scheduling in optical switches has to be frame based because the configuration consumes much time. The frame size is usually selected to be large enough in order to improve transmission efficiency, leading packet aggregation effect. With consideration of the packet aggregation effect, a novel packet scheduling algorithm called permutation-based longest queue first+hold (p-LQF+Hold) was proposed. A set of permutations were calculated by using of the traffic requirement matrix. The permutation with the largest matched occupancy was used to find the matching on each frame boundary. Simulation was made on a 4×4 virtual output queue(VOQ) optical switch under uniform, nonuniform and diagonal Bernoulli and ON/OFF traffic patterns, respectively. The simulation results show p-LQF+Hold can achieve 100% throughput under any admissible traffic that satisfies the strong law of large numbers, and has close to or even lower average packet delay than the popular LQF+Hold algorithm. p-LQF+Hold can guarantees bandwidth requirement and short-term fairness and efficiently accommodate the dynamical packet arrivals.