Research On Failure Restoration Technology In Elastic Optical Inter-datacenter Networks

Elastic optical network(EON)with the advantages of high-bandwidth,high-flexibility and low-cost,is a very promising network architecture to interconnect data centers.However,with the rapid growth of data center services,the transmission capacity on each fiber link is growing.In the event of fiber link failure,there will result in a huge number of data center services interruption.To this end,it is crucial to design efficient failure recovery mechanism to achieve fast and reliable recovery for interrupted services.The failure management technology could be divided into two categories: protection technology and restoration technology.Compared with protection technology,the restoration technology has higher resource utilization rate.What's more,in large-scale datacenter networking environment,spectrum resources become the bottleneck restricting the development of EON-IDC networks,so the restoration technology becomes the preferred survivability technology to resist network failure under dynamic environment.It is worth nothing that,in the recovery process,the high recovery delay and the low recovery success rate are two key issues to be solved urgently.Therefore,this paper proposes a degraded service restoration strategy based on dynamic load balancing and a triggered precomputation restoration strategy based on dynamic routing and spectrum allocation.To improve recovery success rate and reduce the blocking probability,a degraded service restoration strategy based on dynamic load balancing is proposed.Firstly,the dynamic load balancing shortest path algorithm is used for calculating routes to reduce blocking probability.Secondly,the priorities of services are distinguished according to the bandwidth tolerance during recoverying the interrupted services.Then,the degraded service restoration strategy is configured for the low-priority services while the full bandwidth restoration strategy is adopted for the high-priority services.If the high-priority service can not be recovered with full bandwidth provisioning,the existing low-priority services in the network will be degraded to save spectrum resources for the high-priority services.The simulation results show that the proposed restoration strategy attains low blocking rate and greatly improve recovery success rate while guaranteeing QoS for services.In order to effectively reduce the recovery delay and guarantee a high recovery success rate,a triggered precomputation restoration strategy based on dynamic routing and spectrum allocation is proposed.Firstly,the software defined elastic optical inter-data center network architecture is established,while the controller and OpenFlow protocol is extended to customize the network function quickly and flexibly;Secondly,based on this network architecture,the triggered precomputation mechanism is used for precomputating the resoration path to achieve fast recovery for interrupted services;Meanwhile,the layered auxiliary graph of spectrum window plane model is built when performs dynamic routing and spectrum allocation,which effectively achieve the one step routing and spectrum allocation algorithm for multi-granularity services.The simulation results show that the proposed restoration strategy attains low recovery delay and high recovery success rate.