An efficient load adjustment for balancing multiple controllers in reliable SDN systems

Software-defined networks (SDNs) are flexible for use in network traffic routing determination because they separate control and data planes. OpenFlow — the de facto protocol for SDNs — requires a dedicated SDN controller. When a network's coverage increases, a system based on a single SDN controller can experience a severe bottleneck. Using multiple controllers in an SDN may solve the scalability problem. In this paper, to achieve load balancing among controllers, we proposed a load adjustment mechanism for application to each controller. The proposed mechanism comprises three logical components: a load collector, load balancer, and switch migrater. Cbench was used to generate traffic to simulate various loads for each switch, and the experimental results confirmed that the data collection procedure and adjustment of global and local loading were efficient.