Research On The Key Technology Of Optical Network Virtualization Supporting Network Cloud Services

In recent years,with the rapid development of network cloud services,the Internet traffic has exponentially increased.Traditional optical network architecture's issues in scalability and flexibility are highlighted,the network ‘fossilization' problem has become more and more prominent.In order to solve this problem effectively,the researchers proposed the optical network virtualization technology.It is able to build a number of independent virtual networks on the shared underlying network resources through the abstraction,partition and aggregation mechanisms to meet the heterogeneous network requirements of network cloud services.However,the virtual networks must rely on the underlying optical network resources to make sense.Therefore,the mapping problem of VN to the underlying optical network resources becomes a hotspot.Research indicates that the main feature of the network cloud services to the underlying optical network resource is dynamic,so how to map VN to the underlying optical network resources dynamically and efficiently becomes the key to determine the quality of network cloud services.In this paper,the virtualization layer in the SOA-based network cloud services model is modular designed firstly and used as the verified environment of the subsequent mapping algorithms,which makes the verified environment of this paper closer to the real network cloud services' environment.Then,this paper studies two cases which are the increased of resource demands and single-node-failure of dynamic VN mapping problem based on the main challenges of optical network virtualization.In the dynamic VN mapping algorithm for the increased of resource demands,we study two cases which are the increased of virtual nodes' resource demands and the increased of the number of virtual nodes and the mixed integer linear programming(MILP)method is used to modelling.In the heuristic algorithm,the minimum node pressure priority method is used and the load balance of the physical nodes is fully considered in the process of physical node reconfiguration.The simulation results show that the proposed algorithm can reduce the reconfiguration cost and achieve better load balance of the underlying physical nodes.In the study of single-node-failure dynamic VN mapping algorithm,the problem of reconfiguration of virtual nodes on single-physical-node-failure is mainly studied and the integer linear programming(ILP)method is used to modelling.In the heuristic algorithm,the virtual network's topology and the connectivity of the underlying physical nodes are considered synthetically.The optimal physical node for mapping is selected according to the connectivity calculation results.The simulation results show that compared with the contrast algorithms,in despite of this algorithm consumes more mapping time,but it improves the recovery rate of failure VN and reduces the load intensity of underlying physical nodes,so it is available.