A Fast Converging Mechanism for Load Balancing among SDN Multiple Controllers

Load balancing among multiple controllers is a critical issue in the software-defined networking (SDN), since traffic dynamics prevent control-plane loads from being evenly distributed among controllers. Load imbalance may cause some controllers to be overloaded while the other controllers are still underutilized. Though there have been several proposed solutions, they do not consider the convergence time of load balancing. We thus propose a fast-converging load balancing (FCLB) mechanism that seeks to achieve fast convergence for balancing loads (i.e., assigning switches) among the SDN controllers. Fast convergence can rapidly release controllers from being overloaded, thereby shortly recovering network performance and preventing some unanticipated results (e.g., controller crash). Searching for the optimal solution from a large set of switch-controller combinations can lead to a large delay, which can aggravate negative impacts from overloading. We thus leverage the genetic algorithm to find a near-optimal solution. Our simulation results show that FCLB has at least 20.7% faster convergence time than the other mechanisms while achieving better load balancing performance.