Research On Load Balancing Method In SDN Multi Controller Flat Architecture

Software Defined Network(SDN),as an emerging network architecture,completely subverts the traditional network's way of scheduling network flows.Separate the redundant control layer and data layer on the device to achieve centralized control of network flow.The existing multi-controller architecture system mainly has a hierarchical architecture and a flat architecture.Flat architecture is becoming the mainstream method.Under this architecture,multiple controllers need to synchronize and share information with each other and monitor abnormal conditions,but there are also problems such as excessive bandwidth usage of shared information and unsatisfactory switch migration in an unstable network environment.This article mainly proposes algorithms for these two aspects,and builds a system on the experimental platform ONOS.First,a suppression algorithm is proposed for the problem of excessively large share of information occupancy ratio.Using the characteristic that the controller has different real-time requirements for shared information,several thresholds can be set according to the load of the controller,and the corresponding synchronization time period can be given.On this basis,the Improved Shared Information Suppression Algorithm(ISISA)is designed and implemented.After experimental simulation,the algorithm reduces unnecessary bandwidth loss of shared information compared with the traditional way of sharing information,and the timeliness of information is not affected.Second,design and implement a migration domain selection strategy based on the WRS algorithm.Using the characteristic of different remaining processing capacity of the controller,different weights can be assigned to the target controller that meets the migration conditions according to its remaining processing capacity.On this basis,the migration target domain can be finally determined based on the WRS(Weighted random algorithm)algorithm.Experimental simulation shows that compared with the traditional deterministic migration algorithm,this algorithm is better for the migration processing of burst traffic.Finally,the entire multi-controller load balancing system is completed based on the above two algorithms.The system is mainly divided into an information collection module,a migration decision module,a topology discovery module,a suppression algorithm module,a shared information module,and a switch migration module.The suppression algorithm module optimizes the network bandwidth occupied by the shared information module based on the suppression algorithm decision.The migration decision module mainly uses the WRS algorithm to migrate the faulty or overloaded controller domain,so as to meet the robustness and load balance of the entire system.The other modules are mainly the auxiliary suppression algorithm module and the migration decision module,which provide necessary information.