Research On Cross-layer Survivability Strategy For Optical Inter-datacenter Networks

With the advantages of large capacity,high bandwidth and low latency,the elastic optical network could satisfy the requirement of inter-datacenter communication well.However,the reliability of the network is facing unprecedented challenges.Any one fiber failures will result in a huge amount of data loss.Therefore,it is crucial to design an efficient survivability strategy to achieve fast and reliable recovery for interrupted services in optical inter-datacenter networks.The survivability strategy mainly includes protection strategy and restoration strategy,and both of them have advantages and disadvantages.With the high-burst and large-bandwidth characteristics of datacenter services,the traffic load changes unsteadily.Therefore,it has become a key research area to design a high-efficiency survivability strategy in dynamic network environment according to different traffic load condition.In this thesis,a dynamic cross-layer protection strategy based on reliability-aware and a cross-layer restoration strategy based on multipath routing are proposed for high traffic load condition and low traffic load condition respectively.In order to satisfy the reliability requirement of the services and reduce the protection overhead,the dynamic cross-layer protection strategy based on reliability-aware is proposed in optical inter-datacenter networks.Firstly,the software defined IP over elastic optical network architecture is established.By means of the communication between the IP controller and optical controller,the optical layer can be aware of the services' real-time reliability.Secondly,the optical controller could dynamically adjust the protected resources according to the service' real-time reliability.Finally,the release method of the minimal resource occupation block is also designed to select the best order to release the protection routes.Experimental results indicate that the proposed strategy could satisfy the reliability requirement of the services adequately.In the meantime,it performs well on reducing the protection overhead.However,there are insufficient network resources to protect services under high traffic load condition.Therefore,the restoration strategy becomes the foremost way to ensure the survivability of the network.Lacking of available network resources,the failure restoration ratio is lower.In order to improve the failure restoration ratio and reduce the bandwidth blocking ratio in optical inter-datacenter networks,a cross-layer restoration strategy based on multipath routing is proposed.Through the cooperation of the IP controller and optical controller in the architecture of software defined IP over elastic optical network,the network resources can be allocated jointly considering the bandwidth resource on both layers.Based on this,the IP controller could split the failing requests into several sub-paths according to the network resources on the optical layer,and then recover the requests with multipath.Finally,the IP controller calculates the spectrum utilization entropy of each sub-path and transforms the path selection problem into the 0-1 knapsack problem,whose purpose is to choose the most reasonable recovery scheme.Experimental results indicate that the proposed strategy can achieve higher failure restoration ratio and lower bandwidth blocking ratio.