Research On Controller Fault Removal And Load Balancing Of Network Link Based On SDN

In recent years due to the rapid development of Internet technology,the Internet has become an indispensable part of people’s life and production,Especially in recent years,the Internet user number and the amount of data transmission are increasing exponentially.The traditional network based on TCP/IP protocol has been unable to meet people’s daily life and work on the network demand.So researchers have to propose a new network architecture--Software Defined Network(SDN).In recent years,SDN has become a hot topic in the study of future networks.Researchers have mainly studied SDN in two aspects:The first is the study of control plane,whose main research direction is to improve scalability and fault tolerance of the SDN network;The second is the data plane,whose main research direction of researchers is to improve bandwidth load balancing of the network link.Therefore,the main research of this thesis is divided into the following two parts:(1)This thesis proposes Failover Mechanisms for Multi-domain Distributed(FMMD),which mainly addresses the problems that the time of the controller fault removed is too high and how to guarantee load balancing of controller after the controller fault is removed.The method is to perform controller fault removal based on the characteristics of multi-domain distributed SDN network architecture and the concept of master-slave controller in OpenFlow protocol 1.3.0 the controllers in the adjacent area except the master controller of the slave controllers of the independent switches,and these controllers are used as alternate transfer controllers.This thesis determines the priority of each slave controller by calculating the migration efficiency of the stand-alone switch and each slave controller.When the main controller failure,Stand-alone switches(a stand-alone switch is the switch that can not connect to the network due to a controller failure)will be migrated to the slave controllers which have higher-priority and change roles to ensure load balancing.Experiments show that the proposed FMMD removal method effectively reduces the failover time and end-to-end average delay time while effectively controlling the controller overload so that the SDN network controller achieves load balancing.(2)The main research direction in the data plane is load balancing problem of network link based on Fat-Tree data center network of Openflow.There are two main problems because of the method of load balancing problem of traditional network link.First,there are multiple feasible paths from the source address to the destination address in the data center network,and due to the available bandwidths is different caused by the different link bandwidth usage rates and the initial bandwidth of the link,how to select the current maximum average available bandwidth path;Second,how to ensure that the selected path will not cause bottleneck.The Multipath Dynamic Programming(MDP)algorithm is proposed to solve the above two problems.The main step is to choose the largest average available bandwidth path from the set of feasible paths by the dynamic programming algorithm through the Fat-Tree data center network structure and to determine whether the selected path has bottleneck problem.The experimental results show that the MDP algorithm has a better load balancing effect of the network links than traditional Dynamic Load Balancing(DLB)algorithm,by comparing the average bandwidth rate and the average packet transmission delay.