A Dynamic Load Balancing Mechanism for Distributed Controllers in Software-Defined Networking

In recent years, distributed controllers have been designed that the whole network has been divided into several domains with multiple physically distributed but logically centralized controllers to achieve a better performance in both availability and scalability Software-Defined Networking (SDN). However, such distributed architecture is challenged by uneven load distribution among controllers due to the static switch-controller mapping. This paper presents a dynamic and adaptive load balancing mechanism based on a hierarchical control plane for distributed controllers in SDN. We estimate the aggregate load of a controller from the aspect of controller factor and switch factor. Based on load status on each controller, the proposed mechanism can dynamically shift the load from the heavily-loaded controller to the lightly-loaded one via switch migration. Furthermore, by using an adaptive load collection algorithm, the frequency of load information notification is significantly reduced in comparison with existing approaches. The simulation results indicate that the proposed strategy can balance the load of control plane dynamically and increase the throughput of distributed controllers.