The Research And Simulation Of Impairment Awareing RWA Base On Delay And Buffer

Routing and Wavelength Assignment (RWA) is an important issue in opticalnetwork. That denote when call request accrue between a source node and destinationnode, how to routing for two nodes and assign the appropriate wavelength. A goodRWA can greatly improve network’s performance. e.g. balance network’s traffic andimprove the blocking probability. But many RWA is basing on ideal network thatignore physical impairment. This assumption has many faults. The RWA of this paperbase on real network that consider some physical impairment. Although this assumptionis less-than perfect, it is of practical significanceTo give a better solution for RWA, the paper propose a Routing and WavelengthAssignment base on Delay&Buffer with Impairment Aware (DB_IA_RWA). The algorithm assumes the PMD and ASE as major loss. If network failed to find asuitable lightpath for the call request, we can buffer the call request in the subqueue.After delaying some time, network layer will look for available lightpath again. Ifthe waiting time reaches the threshold, the CRwould be removed from the subqueue,a call blocking. The algorithm is a hierarchical graph-based model which can resolverouting and wavelength assignment simultaneously. In the absence of wavelengthconverter, new algorithm can dynamically adjust routing strategy to reasonably assignresource. Finally, simulation result show that this algorithm can effectively reduceblocking probability.The main content of the paper includes:(1) Introduce the meaning of studying the RWA problem, and gives the D andG algorithms flowchart.(2) Introduce the network structure, node structure and the topology structurein wavelength routed optical network in detail. Then give the Delay&Buffer flowchart(3) Blocking probability (BP) performance of traditional RWA algorithm in idealnetwork (T_RWA), RWA algorithm in real network(RWA_real) and IA_RWA has beenstudied used OPNET Modeler. Call that has been respectively refused by networklayer and physical layer in RWA_real is recorded.(4) DB_IA_RWA has been simulated used OPNET Modeler. Compared the newalgorithm with other RWA algorithm, this algorithm can improve BP performance.