A Multi-Controller Placement Strategy Based on Delay and Reliability Optimization in SDN

Software Defined Network (SDN) as a novel network architecture is a subversive revolution of traditional network. It realizes the centralized control of the network by decoupling the forwarding and controlling functions, which greatly improves the flexibility and controllability of the network. Obviously, the layout of controllers affects the networks ability to respond to network events. Therefore, the controller placement is an important problem in SDN community. In this paper, we take the link failure factors into consideration, and make a comprehensive consideration of the number of control path rerouting and the worst-case delay between the controller and the switch in each link failure state, and formulate the problem as a multi-objective optimization problem. To solve the problem, we propose a heuristic method based on particle swarm optimization. Numerical results demonstrate the effectiveness of the proposed algorithm. It also shows that the proposed strategy can guarantee the delay and reliability of the control layer in most link failure states.