Research On Congestion Control Of Software Defined Data Center Network

Nowadays,with the rapid development of Internet and cloud computing,data center plays a key role.Due to the reliability and robustness of data center network,there are multiple paths between servers.However,the traditional congestion control mechanism of data center network can not make full use of these alternative paths and effectively solve the congestion problem of data center.Software defined networks(SDN),a new network architecture,has been widely used in data center network.According to the global information obtained by SDN,we can better monitor the network condition and formulate congestion control strategy.But SDN network architecture also has its inherent shortcomings.If there is no reasonable traffic scheduling strategy or the controller is overloaded,it will still lead to network congestion.Therefore,this paper from the two aspects of traffic scheduling and controller congestion relief to solve the congestion problem of software defined data center network.(1)A congestion control strategy based on multi node label distribution is proposed.The traditional OpenFlow protocol will distribute and install flow table entries on each switch on the traffic path,which causes a great burden on the controller and increases the congestion of the controller.In this paper,we use the method of MPLS label distribution in multiple nodes to reduce the distribution of controller flow table,and reduce the load of the controller.In this paper,a mathematical model is derived to describe the final optimization objective,which is a non-deterministic polynomial problem(NP hard problem),so the greedy algorithm is used to obtain the local optimal solution of the optimization objective function,and the flow table information with MPLS label stack is distributed by the appropriate switch.Finally,the experimental results show that compared with the traditional OpenFlow method,it can reduce the distribution of flow table entries by 60%,and reduce the delay of the controller by about 25%in the environment of large traffic.It can reduce the overall network congestion by reducing the load of the controller and the processing delay of the controller.(2)A traffic scheduling strategy based on fuzzy logic reasoning is proposed.Using the fuzzy logic reasoning model,the link utilization and hop number of the candidate path are taken as the input values.After the steps of fuzzification,rule reasoning and defuzzification,the score value of the path is deduced.Finally,the maximum score of all paths is taken,and the path is our final selected path.The simulation results show that the fuzzy logic algorithm is better than ECMP and Hedera in throughput,load balancing and average round-trip delay,which can effectively reduce network congestion.