Research On Survivability Mechanism Against Disasters Failure In Optical Networks

As the continuous increasing demand for bandwidth of network service,WDM optical network has become the mainly basic network architecture of the communication network,due to its large capacity and high transport speed.Large-scale disasters(such as earthquake,tornado,and tsunami)cause the components(network links and nodes)of WDM optical network disrupted,which lead to massive connections interruption and data loss as well as available network resource rapidly reduction.Moreover,the aftermath of the disasters may further threaten the residual network and impact the survived service connections,which cause the network cannot ensure the reliability of connections.Consequently,the strategies for improving the reliability of network and optimizing the utilization of network resource has been focused on this thesis.In order to address the problem that traditional routing algorithm cannot simultaneously take into account the reliability of connections and the utilization of network resource under the probabilistic network models,a routing strategy based on dual-cost(RSDC)has been proposed in Chapter Ⅲ.In RSDC,both reliability factor and resource factor of links are considered in routing process based on probabilistic failure model.RSDC evaluates the resource cost of network links according to bandwidth demand of different request,and combines the failure probabilityof network links to sets up a dual cost function for network links.RSDC calculates an optimal routing by accumulating reliability of links and delivering the minimum resource cost of path.The simulation results show that RSDC achieves a good trade-off among network service reliability and network resource utilization.In order to address the problem that large-scale disaster failures lead to the network cannot offer reliable transmission,and a large amount of disrupted components causes resource crunch,Chapter Ⅳ proposes a reliability restoration and resource optimaziation strategy based on simulation annealing(RROS-SA).In RROS-SA,single-or double-path dynamically chosen for impacted(disrupted and/or reliability-decreased)connections to adapt the requirement of reliability according to various service level objectives(SLOs).A mechanism named effective-reliability bandwidth has been proposed to assess whether the network resource effectively configurated or not.RROS-SA exploits simulation annealing to optimize network resource utilization,as well as this method can relieve the unfairness degree that caused by the recovery order.Finally the simulation results show that RROS-SA can improve the reliability of network services and achieve satisfactory performance in terms of resource utilization and fairness factor.