超大容量光交换机中器件约束的Clos网络路径设计

Path Design of Clos Network Based on Device Constraint in Large Capacity Optical Switches

基于快速可调激光器和阵列波导光栅的光交换结构是实现超大容量光交换机的理想选择,但是快速可调激光器的快速调谐要求使得空闲时隙的激光器必须保持发光状态,并对有效业务光信号造成干扰。为了解决此问题,提出了采用无效业务填充空闲时隙的方法,从而使得系统中的有效业务不再受到无效业务的干扰。通过两种不同的方法生成无效业务即随机策略和顺序策略,仿真研究和对比了两种策略在不同业务量下各自的优势。同时,为了降低包含无效业务时的调度算法重排次数要求,还进一步提出了阈值策略计算无效业务路径的方法,并通过仿真验证了该方法可以大大降低重排次数,提高调度算法的计算效率。

Optical switching architecture based on fast tunable laser and arrayed waveguide grating is an ideal choice to realize optical switches with large capacity. However, the fast tuning requirement of the fast tunable laser makes it necessary for the fast tunable laser to keep seeding light even under idle state without data, and the optical light from the idle fast tunable laser may introduce significant interference to a valid optical signal if they are routed to the same receiver. In order to solve the influence of the fast tunable laser constraint, a method is proposed to use the invalid demands to fill idle time slots so that the valid demands and invalid demands have different output ports and no longer interfere with each other. Two different methods to generate the invalid demands are proposed, namely the random strategy and the sequential strategy, and the performances of the two strategies with different traffic loads are studied and compared through simulations. Meanwhile, in order to reduce the number of rearrangement in the scheduling algorithm, a threshold-based strategy to find the path for an invalid demand is proposed. The simulation results show that this threshold-based method can greatly reduce the number of rearrangement, and improve the computation efficiency of the scheduling algorithm.