Research On Traffic Engineering In SDN/OSPF Hybrid Network

Currently,more and more traditional network begin the evolution to Software Defined Networks(SDN)with the development of SDN technology.However,SDN comes with its own set of challenges such as scalability,robustness and standard setting,which make a full SDN deployment inconvenient in the loger-term.Therefore how to introduce SDN in an existing network incrementally has become a research focus.In the process of network evolution,there will be the hybrid networks,where SDN and traditional protocols coexist.This thesis focuses on optimizing the network performance by Traffic engineering(TE),a mechanism arming at improving the network performance,in SDN hybrid network.Traffic engineering is an important mechanism to optimize the performance of a data network by dynamically analyzing,predicting,and regulating the behavior of the transmitted data.The trafic engineering in this thesis is to optimally use the limited SDN ability provided by a small amount of SDN nodes in the hybrid network to minimize the maximum link utilization in order to improve the performance of network.The algorithm proposed is divided into three parts.Firstly,partition the initial Open Shortest Path First(OSPF)domain with SDN nodes into sub-domains under the sub-domain partition algorithm aiming at maximizing cross-regional traffic,use the partition algorithm to determine the number and location of SDN nodes during the network migration to achieve the optimal effect of TE.Secondly,cross-regional traffic path correction algorithm is responsible for balancing the link utilization by tuning the Link State Advertisement(LSA)of OSPF protocol to switch the traffic path between different tunable paths.At last,distribute the traffic accumulate at SDN nodes in the downstream paths according to the distribution ratio determined by the Fully Polynomial Time Approximation Schemes(FPTAS),by this way the untunable paths and the flow with large traffic can be routed by multi-path routing to maintain a lower network link utilization.Compared to the existing TE in SDN hybrid network,the algorithm proposed can be more effective in sharing the traffic load of congestion links between free links,so that it can significantly reduce the maximum network link utilization and get a better network performance.