Research On Methods Of Survivable Virtual Network Embedding And Resource Allocation In Elastic Optical Networks

In recent years,with the emergence of new services such as driverless,virtual reality and online games,it has brought severe challenges to the communication backbone network with limited transmission capacity.The flexible optical network based on orthogonal frequency division multiplexing technology has a more flexible way of spectrum resource allocation,which can effectively alleviate the current shortage of network spectrum resources.At the same time,in order to solve the problems of network structure rigidity and poor scalability,network virtualization is proposed as a key technology.Network virtualization allows multiple separated and heterogeneous virtual networks to share the underlying physical network resources,which greatly improves the flexibility of the network and the utilization efficiency of spectrum resources.However,there are many problems to be solved in the implementation of network virtualization,among which the virtual network embedding problem is the most difficult.In addition,once affected by factors such as link aging,natural disasters,man-made damage,etc.,the optical fiber links in the elastic optical network are extremely prone to failures,which will bring huge economic losses to operators and network tenants.Therefore,how to effectively embed the virtual network on the elastic optical network and ensure its survivability is very important for research significance.To address the problems of serious spectrum resource consumption and high spectrum fragmentation during virtual network embedding under single link failure scenario,a survivable virtual optical network embedding algorithm based on resource awareness of correlation lightpaths(SE-RACL)is proposed in the third chapter.Firstly,according to the multi-dimensional attributes of nodes,the importance sorting formulas of virtual nodes and physical nodes are designed to increase the relevance between node embedding and link embedding and reduce the bandwidth consumption of link embedding.Secondly,in the spectrum allocation process of the working lightpath,the spectrum block matching degree formula is designed by combining the spectrum fragmentation degree changes and resource reductions of correlation lightpaths,which is used to optimize the network spectrum resource allocation.Finally,in order to improve the sharing degree of protection resources and the success probability of spectrum allocation under single link failure,a correlation lightpaths spectrum allocation method based on the minimum free frequency slot consumption is proposed.Simulation results show that compared with the comparison algorithms,the acceptance ratio of the proposed SE-RACL algorithm is increased by 14.7% at most,and the spectrum utilization is increased by 13.8% at most.To address the low spectrum utilization and the problem that virtual links may be embedded to the longer physical lightpaths during virtual network embedding under multi-link failure scenario,a survivable virtual optical network cooperative mapping algorithm based on awareness of reliability and time-frequency resource(SCM-ARTR)is proposed in the fourth chapter.Firstly,in order to improve the utilization of spectrum resources and realize the differentiated protection of the working lightpaths mapped by different virtual links,the reliability measurement formula of physical components for routing is designed.Secondly,in order to reduce the generation of spectrum fragments in the network,a formula of spectrum block matching degree is designed based on the time domain and frequency domain properties of spectrum resources,which is used to select the spectrum block that has the least impact on the integration of network spectrum resources among different candidate spectrum blocks.Finally,the virtual node ranking formula is designed to improve the quality of feasible solutions and reduce the time complexity of the algorithm,and the heuristic information is designed to enhance the correlation between node mapping and link mapping.Simulation results show that compared with the comparison algorithm,the average mapping hops of the proposed algorithm is reduced by 17.6% at most,and the spectrum utilization is improved by 7.8% at most.