The Study Of Routing Problem In RWA Networks

With the development of optical networking technologies, opticalfiber communication has been an important way for constructing thebroadband backbone networks. Optical network that bases on WavelengthDivision Multiplexing(WDM) is to be the focus of the opticalcommunication research area because of its enormous bandwidth andflexibility. Routing and wavelength assigmnent (RWA) is considerd to bea key problem in such WDM networks. Given a call or lightpath to beestablished between two nodes, the RWA problem is to find a route fromthe source node to the destination node and then assign a wavelength tothis route.In this paper we study the route sub-problem of WDM networks inorder to improve the network performances. The general RWA weightdefinitions are studied firstly. Then based on these definitions, two newweight definitions are presented. New definitions take more facts such aswavelength assignment into account. And the new weights are evaluatedby simulations and analysis. Afterwards, a research on small networkrouting problem is focused on the shortest routing algorithms and MixedInteger Linear Programming algorithms of RWA networks. The optimized route methods are solved and evaluated in simulations by the mathematicalsoftware LINGO. Then a route algorithm based on genetic algorithm isproposed for larger networks. This algorithm is aimed at choosing theshortest route, and is realized by VC++ programs. The correctness andadvantage of this algorithm are proved in the NSFNET network routeproblems. At last, because the granularity of connection request is muchsmaller than the granularity of one wavelength, the route problem at theconnection level is considered. For the given mesh network resources, theshared protection alternate routing algorithm and dedicated protectionalternate routing algorithm under the shared risk link groups (SRLG)constraints are presented. Both of the two algorithms support differentpriority of the traffic and the objective is to maximize network throughput.The simulation results based on NSFNET network show that theperformances of the two algorithms we proposed are improved, especiallyfor blocking probability and wavelength usage.