Research On SDN Controller Based On Openflow Protocol

With the rapid development of mobile Internet,the traditional network architecture can not meet the requirements of high quality Internet services.Under this background,software defined network(Software Defined Network,SDN)is proposed,aiming at the defects of existing network for improved architecture on the Internet.As an innovative network architecture,SDN separates the data plane from control plane of the network device,so that the controller can realize the flexible scheduling of the data in the basic network facilities through the Openflow protocol.SDN control layer is the key layer between SDN network data layer and application layer.Its function is not only to operate the data layer,but also to provide application programming interface(API)for the application layer.At present,the existing types of controllers are the specific realization of this plane.Openflow,as the representative of the SDN protocol,is one of the key technology to realize the southbound interface,and provides definition for the communication between the control layer and the data layer in the SDN networkFirstly,the development status of SDN and Openflow protocol are analyzed.This thesis makes an investigation on the practical application of SDN in data center,telecom operators and data center.Then,the type and function of Openflow protocol flow meter principle and Openflow message are studied deeply.Secondly,three controllers,POX,Ryu and Floodlight are reaserched.And their advantages and disadvantages,features and structure are compared and ananlysed.In the Linux system the controllers has been carried on the actual deployment.Then Mininet and Cbench are used for testing their performances.Thirdly,the research focuses on the improvement of topology discovery mechanism.Through the analysis of the defects of the current topology discovery mechanism,the thesis puts forward the improvement direction and the concrete method.The feasibility of the algorithm is studied,and the improved algorithm and scheme are developed.The performance of the CPU controller,the number of packets sent and the bandwidth occupied by the controller under different topologies are tested and compared in three aspects.Through the analysis of the load balancing method,Finally,this thesis proposes and implements a SDN based load balancing application in the host end.The program requirements,formulate the design principle,load balancing algorithm is proposed.And the GNS3 network simulation software is used for establishing the experimental test platform.The performance of load balancing is tested by comparing the network performance under the condition that the different numbers of network interfaces and inconsistent network interface capacity.The experiments show that the proposed load balancing scheme is feasible and has shown good performance.