Design And Simulated Implementation Of Sub-Path Protection Algorithms In Meshed WDM Optical Networks

With the explosive increase in Internet traffic and the tremendous demand in bandwidth and capacity, the technique of Wavelength Division Multiplexing (WDM) becomes the core of the next generation backbone networks. Since each wavelength channel has the transmission rate over several gigabits per second, the failures of fiber links or nodes may lead a lot of traffic to be blocked. Therefore, survivability has emerged as one of the important issues in the design of WDM optical networks. The strategy of survivability mainly includes protection and restoration. Since the protection technique has faster failures recovery time, many researches are based on the protection.Based on the concept of protection, this thesis first designs two Mix Sub-Path Protection (MSPP) algorithms named Dedicated Mix Sub-Path Protection (DMSPP) and Shared Mix Sub-Path Protection (SMSPP). The two algorithms both compute the working path and the protection path (or sub-protection path) by running the Dijkstra algorithm, and they also take the restriction of protection-switching time and the load balance into consideration. Simulation results show that, compared to traditional algorithms, DMSPP and SMSPP algorithms can obtain lower network blocking ratio and less protection-switching time.This thesis also designs a sub-path protection algorithm, Auxiliary Topology Protection (ATP). According to the protection-switching time constraints, ATP fiest searches multiple groups of primary and backup paths for each node pair in the network by an off-line manner, and then maps these paths to the auxiliary topology. When a connection request arrives, ATP only need run one time of Dijkstra algorithm to find a virtual route that meets the protection-switching time constraints and may consist of multiple sub-paths in the auxiliary topology. In the following, according to the load balance or shared resources policy, ATP chooses an optimal group of sub-paths. The simulation results show that ATP algorithm has a lower blocking ratio than traditional protection algorithm and also has lower time complexity than conventional sub-path protection algorithm. In addition, the advantage of ATP appears more obvious especially when network resource is rich.