Study Of Virtual Optical Networks Embedding Algorithm Over Elastic Optical Networks With Shared Protection

In recent years,with the increasing of emerging services such as video conferencing,high definition television and cloud computing,the demand for network bandwidth resources increasesrapidly and the traditional networks architecture is facing serious challenge.Elastic optical networks based on optical orthogonal frequency division multiplexing technology adopt a flexible bandwidth allocation mode which divides the bandwidth resource into smaller spectrum granularity,and adaptively allocates the number of frequency slots and select the modulation format according to the service size.Therefore,elastic optical networks can alleviate the pressure of bandwidth resource shortage.Network virtualization technology allocates resources for heterogeneous virtual networks through abstracting the underlying networks resources into resource pools.Network virtualization technology can effectively improve the scalability of the network and promote the sharing of physical devices in elastic optical networks.However,due to the continuity and consistency of the spectrum in the elastic optical networks,the virtual networks mapping problem is extremely difficult to solve.In addition,the fiber optic link in the network has a certain probability of failure due to aging or man-made,and it makes the business in the optical transport networks failed,and causes great economic losses to society.Therefore,how to ensure the survivability of virtual networks and allocate resources reasonably in an elastic optical network has become an important research topic.This paper studies the mapping method of virtual networks in elastic optical networks,and provides the security guarantee strategy for virtual networks under the probabilistic failure of fiber optic link in the underlying networks.First of all,in order to solve the problem of low spectrum resource utilization caused by long physical link in virtual networks mapping,a strategy of survivable virtual optical networks coordinated mapping algorithm,based on the distance between nodes and spectrum dispersion awareness is presented in the third chapter.Firstly,the strategy designs a new physical nodes evaluation formula by analyzing the computing resources and their positions in the entire physical networks topology,so as to ensure the degree of aggregation of the virtual nodes in the underlying networks.In the process of link mapping,the concept of spectral dispersion is proposed.By comparing the degree of spectral dispersion of candidate paths,the path with fewer spectrum fragments can beselected tomap virtual links.At the same time,in order to ensure the survivability of the virtual networks in the case of a single link failure,on the basis of shared path protection,the strategy proposes the protection strategy with the maximum spectrum sharing,and it increases the spectrum sharing degree on the protection path.The simulation results show that the proposed mapping algorithm can not only reduce the bandwidth blocking rate,but also improve the utilization of spectrum resources.Secondly,in view of the fact that the security of the virtual networks can not be guaranteedcaused by the probabilistic failure of the optical fiber link in real life,a diverse virtual optical networks mapping strategy based on security awareness is proposed in the fourth chapter.The strategy designs the physical node weight formula by considering the hops between nodes and the bandwidth of adjacent links to avoid the far location of the mapping between the virtual nodes.Besides,a path-balanced link mapping mechanism is proposed to minimize the overloaded link.In order to improve the acceptability of virtual networks,the strategy designs a resource allocation mechanism that allows path cutting when a single path is unavailable for low security.In the routing,a cost function considering security and spectrum consumption is designed,and it also consider the difference of time delay to ensure the security of delay-sensitive services and save spectrum resource in order to serve more virtual network requests.Moreover,the strategy improves the virtual optical networks acceptance rate by configuring the shared protection path when the underlying networks can not meet the security requirements of the requests.The simulation results show that the strategy proposed in this paper can improve the spectrum utilization and virtual optical networks acceptance rate in the probabilistic fault environment,and reduce the bandwidth blocking probability.