Virtual Network Embedding And Resources Allocation Strategy In Elastic Optical Networks

In recent years,with the development of cloud computing,video conferencing,high-definition television and internet of everything,there has been a huge challenge to the existing backbone network's transmission capability.The traditional backbone network adopting wavelength division multiplexing technology divides an optical fiber as multiple wavelength sub-channels for improving the utilization of each fiber resource.However,with the further advancement of internet of everything,the WDM networks suffer from the disadvantages of the fixed spectrum allocation mode and the single modulation level.As a result,resource utilization is low and services cannot be transmitted normally.Fortunately,optical networks,especially elastic optical networks based on orthogonal frequency division multiplexing can greatly improve the utilization of resources in the network with their fine-grained bandwidth allocation and flexible selection of bandwidth modulation levels.At the same time,in order to solve the problem of network rigidity,network virtualization is proposed as the key technology.It virtualizes the underlying network resources into virtual resource pools through network virtualization technology,which can support multiple heterogeneous networks to share infrastructure resources and greatly improve the utilization of resources.Among them,the most critical issue of virtual network technology is virtual network mapping.Therefore,it is of great significance to study virtual network mapping and resource allocation in elastic optical networks.This paper mainly analyzes and summarizes the problem of virtual network mapping and resource allocation in the flexible optical network.The paper summarizes the shortcomings of existing researches and proposes a new virtual network mapping and resource allocation strategy to improve the utilization of resources.The specific content of the thesis and innovative work are mainly the following aspects.First of all,in order to solve the existing problems that the virtual nodes are too far to map and consume more spectrum resources and energy during the two-phase mapping process,a genetic multi-objective optimization strategy is proposed.The strategy uses energy consumption and frequency consumption as optimization goals and designs a population initialization scheme based on virtual node mapping and virtual link mapping.In the crossover process,in order to improve the diversity of populations and speed up the convergence,an adaptive crossover operator based on hierarchical comparison is proposed.Simulation results show that the proposed algorithm can effectively reduce the blocking rate and energy consumption and improve the utilization of resources.Secondly,aiming at the problem of uneven resource consumption in elastic optical network mapping,fragmentation-aware based on time and spectrum domain of virtual network mapping algorithm(FA-VNM)is proposed in this paper.Fragment formula jointly considering the time fragment and spectrum fragment is devised to minimize the spectrum fragments during the allocation of resources.Further,in order to balance the network resources consumption,load balancing based on degree of virtual network mapping algorithm is proposed on the basis of FA-VNM.In the stage of node mapping,physical node average resource carrying capacity is introduced and the physical node with larger average resources carrying capacity is mapped first.In order to balance the resource consumption in physical path,weight value of physical path is calculated in the stage of link mapping.Then,according to the weight value of each physical path,virtual links are mapped to achieve the purpose of load balancing for reduce the blocking rate.Simulation results show that the proposed algorithm can effectively reduce the blocking rate and improve resource utilization.