| The rapid development of computer technology leads to explosive growth of network traffic.The traditional TCP/IP network is difficult to meet the demands of the current users because of its complex and closeness.The emergence of Software Defined Network(SDN)has brought hope to solve the above problems,SDN has become a hot topic in the future network architecture.SDN can separate the control function and forwarding function of the underlying equipment in the traditional network,and has the advantages of flexible control of network traffic and programmability.The load balancing algorithm based on SDN can reasonably allocate network resources through centralized logic and real-time monitoring of the controller,which can improve resource utilization,effectively avoid congestion and adapt to the network status dynamically.This thesis summarizes the background,current status,the concept and related technologies of SDN,and analyzes the advantages and disadvantages of load balancing algorithms.The main researches of this thesis are shown as follow:(1)The controller becomes a centralized controller in the multi-controller distributed control plane,which will lead to be blocked and load imbalance of control plane.This thesis set the threshold for load balancing mechanism.When the load of controller reaches a threshold,this controller preferred to migrate the Packet in message that has largest load to the controller whose load is the lowest in its neighbor domain,which can fully utilize the network resources and effectively relieve the overload condition of the controller and ensure the load balancing of the entire control plane.This thesis uses Mininet for simulation experiment and results show that the load balancing mechanism can effectively prevent the controller from blocking and improve the controller utilization.(2)SDN technology is applied to data center network.To solve the problem of network congestion caused by the elephant flow that carried the large amount of data in the center network,a load balancing mechanism of elephant flow based on SDN is proposed.The controller monitors the network state in real time.When network load exceeded the threshold,first,the system detected the network traffic and identified the elephant flow.Then the controller split the detected elephant flows down into multiple mice flows by Openflow feature.Finally,the controller dynamically calculated the minimum load switch according to the collected network topology and link states from data plane,which can effectively avoid the network load imbalancing problem caused by the elephant flow.The simulation experimental results show that EFLB mechanism achieves network load balancing by improving the network throughput and link utilization. |
