Multiple-level threshold load balancing in distributed SDN controllers

Abstract

The distributed Software-Defined Networking (SDN) approach has been adopted to address the scalability issue linked to the use of a single SDN controller, particularly in large-scale networks. However, this method gives rise to a new challenge of uneven load balance on the distributed SDN controller. Several studies tried to solve this issue but they have focused only on balancing the load when an overload occurs and have not achieved the load balance continuously. In this paper, we propose the multiple threshold load balance (MTLB) switch migration scheme to achieve continuous load balancing among the controllers. This approach classifies the load into several gradual levels that represents the basis for the switch migration when the load of a controller differs from others, which lead the threshold value to be dynamically adjusted. Moreover, our scheme reduces the overhead of unwanted update operations among the controllers by adopting the controller load status as an indicator for disseminating the load information. We implement our scheme using the Floodlight controller and Mininet emulator. The experimental results show that our scheme has better comprehensive performance than the other schemes in terms of response time, control overhead, and throughput rate.