Multi-level threshold SDN controller: dynamic load balancing

Deploying multiple controllers in the control panel of software-defined networks increases scalability, but it brings challenges. Several articles have tried to solve this problem. But all the articles were either single-threshold, as a result of which there is no precise classification of controllers, or if they used a multi-level threshold, they considered the capacity of the controllers to be the same. In this article, the load balancing of controllers is discussed, which is used to accurately determine the status of controllers from multi-level thresholds, and switch migration operations are used to balance the load. In this operation, the criteria of the degree of load imbalance of the target controller and migration efficiency, which includes the level of the target controller after the switch migration operation and the distance between the migrant switch and the target controller, were used to select the suitable target controller and the migrant switch. The proposed scheme reduces the controller response time, migration cost, communication overhead, and throughput rate. The results show that our scheme has better comprehensive performance than the other schemes in terms of response time.