Research On Survivable Virtual Optical Network Embedding Method For Improving Resource Allocation Efficiency In Elastic Optical Networks

The explosive growth of network traffic has brought tremendous challenges to the communication backbone optical networks with limited spectrum resources.The elastic optical networks with orthogonal frequency division multiplexing as the core technology adopts optical devices with variable bandwidth and fine-grained spectrum allocation,which improves the efficiency of spectrum resource utilization.At the same time,network virtualization technology can make multiple virtual networks share the underlying infrastructure by abstracting physical network resources.Therefore,it is introduced into elastic optical networks to further improve the resource utilization of elastic optical networks.However,the introduction of network virtualization technology also brings a lot of challenges to the elastic optical networks.The most critical challenge is the research of virtual network embedding method.In addition,more and more services are transmitted in the optical fiber link.Once the fiber link fails,it will cause huge losses to operators and network tenants.Therefore,the thesis has made in-depth research on survivable virtual optical network embedding methods to improve the resource allocation efficiency in elastic optical networks.The third chapter of the thesis is aimed at the problems of high bandwidth blocking probability and severe spectrum fragmentation during virtual optical network embedding in a single link fault scenario,and proposes a survivable virtual optical network embedding algorithm based on resource mean and spectrum coherence-aware.Firstly,in order to enhance the cooperation between node embedding and link embedding,the algorithm evaluates the spectrum resource mean of candidate physical nodes during node embedding.Secondly,when assigning spectrum to the working lightpath embedded by the virtual link,the algorithm preferentially selects the available spectrum block that maximizes the spectrum coherence;meanwhile,it improves the traditional minimum idle frequency slot consumption algorithm and proposes a spectrum coherence-aware spectrum allocation method of protection lightpath.Finally,when the virtual link embedding fails due to insufficient spectrum resources on a single path,this algorithm designs the path splitting methods that can distinguish the lightpath spectrum resources.Simulation results show that the proposed algorithm can effectively reduce the bandwidth blocking probability and improve the utilization probability of spectrum resources.The fourth chapter of the thesis is aimed at the problems of low success probability of virtual optical network embedding and serious spectrum fragmentation in spatial division multiplexing elastic optical networks under multi-link failure scenario,and proposes an efficient survivability embedding algorithm of virtual optical network for service reliability.In virtual node embedding,the algorithm designs a weight evaluation criterion that considers the distance between physical nodes and the available spectrum blocks on the adjacent links.In virtual link embedding,the algorithm designs a method of working lightpath selection considering the spectrum resources and reliability,realizes the purpose of jointly optimizing the spectrum utilization and reliability,and designs a protection lightpath selection strategy to improve the reliability and bandwidth sharing of protection lightpath.At the same time,in order to further improve the probability of protection bandwidth sharing,the spectrum partition method is introduced,and the spectrum allocation method based on spectrum integration factor-aware is designed to make the network spectrum resources more integrated.The simulation results show that the algorithm significantly improves the acceptance probability of virtual optical network requests and reduces the bandwidth blocking probability.