The Research Of Global Dynamic Feedback Congestion Control Algorithm Based On SDN Architecture

Along with the development of the Internet,the services and the amount of data in the Internet shows an explosive growth.Having experienced nearly 20 years,the traditional Internet architecture has got to the bottle neck period,which is difficult to adapt to the new changes in the Internet.SDN,however,breaks the limits of traditional network architecture,because it provides new methods to the problems in the Internet by its separation of controlling plane and data-forwarding plane as well as network programmability.The research content of the paper is as follows:First and foremost,based on the heterogeneous network between wired and wireless network,the paper completes the design and implementation of OpenFlow switch based on the idea of SDN and proposes a program for the efficient integration of wired and wireless network.The controller can manage the wireless switches and wired switches as the same time.In this way,it can control the whole resources on the global network in a unified manner.The program solves the problem of relatively independence between wired network equipment and wireless network equipment in traditional networks.Secondly,this paper designs the algorithm to control the congestion by monitoring the state of the whole network links,Based on the fact that the controller in SDN can monitor the link state and dynamically dispatch the data flow.The algorithm can re-plan the path according to the multipath for the data flow before the network link is congested,and can determine the optimal path for flow forwarding according to the link state.Considering the short duration of short flow in the SDN network,and the high real-time requirements,excessive scheduling may cause its delay to increase,which is contrary to the expectation.The algorithm distinguishes between long and short data flow in the network and only dispatchs long flow.If there are multiple long flow waiting for dispatching,the algorithm will calculate the dispatching value of flow according to the size of the bandwidth occupied by them and the number of congestion links that they are forwarded through.Then the algorithm will give top priority to the long flow with the biggest dispatching value,which will be forwarded firstly.Finally,the paper adopts Mininet to simulate the heterogeneous network environment of wired and wireless networks.And the whole network is controlled by the RYU controller.The paper conducts experiment to check the effectiveness of this algorithm by deploying the relevant modules.Compared with the CAAS algorithm and SDT algorithm which are based on SDN,the algorithm in this paper can effectively relieve the network congestion and can improve network link utilization and throughput,reduce time delay.this paper,Through the interface provided by RYU controller,the paper completes the design and implementation of the platform to control the network,The platform can visually display the network status,and can achieve the control of the network.