一种新的WDM光传送网保护设计算法

在WDM网络中,由于光路之间存在的依赖性,物理网络的单链路失效可能会造成虚拓扑不连通而使上层网络(SDH、ATM或IP)无法使用自身的恢复机制来恢复受影响的业务,因此虚拓扑在嵌入物理拓扑时必须避免发生这种情况.已有的分离备用路径(Disjoint Alternate Path,DAP)算法总是假设网络所有波长路由节点都具有全波长转换能力.本文提出的LG_-VTMDP保护设计算法利用分层图同时解决路由和波长分配两个子问题,并考虑了负载均衡和物理链路的容量限制.实验结果表明LG_-VTMDP算法优于DAP算法和已有波长分配算法组合后的性能.本文还在此基础上提出了一种有效的波长转换器放置算法WCP算法.

A New Algorithm of Design Protection for Optical Transport Networks

In a WDM transport network,internal dependence of lightpaths could lead to the critical status that the failure of a physical fiber leaves the virtual topology unconnected.This may make the restoration of service by the higher level networks using the WDM network (such as SDH,ATM or IP) impossible.It is necessary to avoid the above cases while embedding virtual topology into physical topology.Existent Disjoint Alternate Path (DAP) algorithm always assumes that all network nodes have full-range wavelength conversion capability.A new heuristic algorithm,called Virtual Topology Mapping for Design Protection Based on Layered Graph (LG -VTMDP),used in design protection for WDM optical networks is proposed in this paper.The algorithm considers two problems of routing and wavelength assignment simultaneously.Load balancing and capacity constraints of physical links are also considered.The LG -VTMDP algorithm is shown to perform better than the combination of the DAP algorithm and existent wavelength assignment algorithms.Based on the result of the LG -VTMDP algorithm,an efficient Wavelength Converter Placement (WCP) algorithm is presented subsequently.