Research On Lightpath-based Multicast Traffic Grooming Algorithm In WDM Networks

With the rising popularity of multicast applications,more and more multicast applications such as multiparty conferencing,video distribution and HDTV are becoming increasingly popular.A high-capacity and high-throughput network is urgently needed because of the rapid growth of the traffic.Various algorithms using either lightpath or light-tree schemes have been researched for dynamic multicast traffic grooming in meshed wavelength division multiplexing networks.Algorithms using the lightpath schemes can achieve a high link utilization and low blocking probability.On the other hand,Algorithms using the light-tree schemes can decrease the numbers of transceivers and reduce the energy consumption.This thesis focuses on the lightpath-based multicast grooming algorithms which aim at reducing the traffic blocking probability as many as possible.After analyzing and summarizing these two kinds of lightpath-based multicast grooming methods in detail,a new multicast grooming algorithm is proposed to reduce the blocking probability,which takes the advantages of them and avoids their shortcomings.The main work of this thesis is as follows:(1)A lighpath fragmentation based on integrated graph algorithm is proposed.The algorithm selects the routes in the integrated graph with the combination of lightpaths and physical paths,which solves the problem of ignoring the existing multi-hop lightpaths because of the fragmentation in the physical topology respectively.Comparing to the existing algorithms,the simulation results show that the new algorithm can reduce the blocking probability in most instances.However,the performance is not very good in some cases.So the lighpath fragmentation based on integrated graph algorithm is improved,which chooses the routes by comparing the hops rather than choosing existing lightpaths first on the basis of origin lightpath fragmentation.The algorithm avoids long lightpaths.Numerous simulation results show that the algorithm can achieve good results in different parameters.(2)Since the algorithm chooses the shortest path every time,a node or a path to be quickly consumed.So,before deciding to segment the path,it is necessary to consider whether to use this path.In order to balance the use of transceiver resources and wavelength resources,a path weight function is defined and an adaptive multicast grooming based on network resources algorithm is proposed.Simulation results show that the algorithm can further improve network performance and reduce the blocking probability.Furthermore,the way of considering the least remaining bandwidth of existing lightpaths is applied in the selection of the lightpaths.The simulation results show that the way of optimizing resources allocation can reduce the blocking probability by 1%.