A robust-link controller placement model for large-scale software defined networks

The software defined network (SDN) is a novel flexible network architecture. For the purpose of facilitating management, multiple controllers need to be placed in large-scale SDN. When a link failure occurs, the path can be re-planned by the control layer. However, unreasonable controller placement scheme brings about a sharp latency increase between controllers and switches. The reliability of the SDN is therefore affected. To this end, we define a link robust distance (LRD) by considering the states during link failures and non-link failures. Then, we use it design a robust link controller placement model (RLCPM) which can reduce the impact of link failures on the delay between the controller and the switch. In addition, we design a heuristic algorithm with low-time complexity to solve the RLCPM more effectively. Experimental results show that, compared with other models, RLCPM simplifies the controller placement problem when considering a link failure. The maximum latency between controllers and switches of the obtained controller placement scheme is lower.