Research On Random And Correlated Failure Oriented Surviving Algorithms In WDM Optical Networks

As the requirement for transmission bandwidth continuously increases,the WDM(wavelength division multiplexing)optical networks have become the most important telecom network infrastructure for its massive carrying capacity of data and services.In such large-scale backbone networks,if any component(link/node)failure(s)or damage,might cause large amount of disruptions of service connections and loss of data,even induce severe traffic congestions,leading to huge economic loss of carrier companies and customers.Therefore,the network survivability technology is always a great concern of optical communication field.Based on a static service model,this thesis researched the optical network survivability algorithms for random failures and/or correlated failures,including 1)recovery-time aware hybrid path protection algorithm against double-link failures,and 2)reliability level sustained survival algorithm for post-disaster networks.Aiming at the requirement for surviving against double-link failures,studied recovery-time aware hybrid path protection algorithm.By introducing a constraint of service connection recovery time,as well as exploiting the characteristics of short service switching time of dedicated protection and high resource utilization ratio of shared protection,the proposed algorithm cooperates the dedicated path protection(DPP)and the shared path protection(SPP)to solve the conflict between the service switching time and the network resource utilization ratio,then,in accordance with the service level agreement(SLA),preferentially assigns protection resource for high-level services under a lack of network resource,so as to provide flexible recovery-degree-differentiated resource deployments for multi-level services.The simulation results indicate that,compared with the traditional DPP and SPP,the recovery-time aware hybrid path protection can meet the requirement of service recovery-time threshold,while achieving a good trade-off among average recovery-time,network resource utilization ratio,and service connection recovery degree.Aiming at the severe network destruction caused by large-scale disasters,studied reliability level sustained survivable algorithm for post-disaster networks.The proposed algorithm,based on a dynamic probabilistic failure model,provides reliability differentiated restoration and/or protection deployment for various levels of service.First,according to the given reliability thresholds of different service levels,it utilizes a heuristic algorithm to reroute working paths and/or calculate protection paths for the influenced(interrupted or currently not interrupted but reliability decreased under a given threshold)service connections during a disaster.Then,according to the original bandwidth requirements and/or the augmenting bandwidth requirements for post-disaster traffic burst,it exploits a mixed integer linear programming(MILP)to conduct a bandwidth-degradable optimal resource deployment for different levels of service.The simulation results indicate that,compared with the existing algorithm of self-adaptive degradation re-provisioning in post-disaster,the proposed algorithm can guarantee the required service reliability for different levels of service and achieve a satisfactory performance in terms of connection loss ratio and traffic loss ratio.