A Fair Service and Dynamic Round Robin Scheduling Algorithm

Abstract

调度策略是核心路由交换设备性能的重要保证.针对联合输入交叉节点排队(combined input and cross-point queuing,简称CICQ)交换结构现有调度策略在复杂度或性能方面存在的缺陷,深入探讨了CICQ交换结构调度策略设计的基本准则,并提出了CICQ下虚拟通道的概念.基于基本准则和虚拟通道概念,提出一种简单、高效和公平服务的动态轮询调度策略——FDR(fair service and dynamic round robin).其算法复杂度为O(1),具有良好的可扩展性;并依据虚拟通道的状态为其分配调度份额,具有良好的动态实时性能,能够适应流量负载非均衡的网络环境.SPES(switching performance evaluation system)仿真结果表明,该算法具有良好的时延、吞吐量和抗突发性能.;Scheduling policies are playing significant roles in guaranteeing the performance of core routing and switching devices. The limitations in complexities and extensibilities of current combined input and cross-point queueing switching fabric's scheduling policies are first analyzed. Then, based on this analysis, the principle for designing high extensible scheduling policies and the concept of virtual channel are proposed. Based on the principle and virtual channel, it comes up with a dynamic round robin scheduling algorithm-FDR (fair service and dynamic round robin), which is simple, and of high efficiency and fair service. FDR is based on round robin mechanism, whose complexity is only O(1). It allocates the scheduling share for each virtual channel according to its current states, thus, FDR has good dynamic and real-time performance, and it can adapt to unbalanced traffic load network environment. Simulation results under SPES (switching performance evaluation system) show that FDR exhibits good delay, throughput and anti-burst performance.