Resilient placement of SDN controllers exploiting disjoint paths

Abstract

AbstractTraditional IP networks are difficult to manage, owing to their rapid expansion and dynamic changes. Software‐defined networks are introduced to simplify network management by separating the network control plane from the packet forwarding plane. Using one or several controllers, SDN switches can be configured to forward data packets to their destinations. The controller placement problem aims to determine the number of controllers and their locations to meet network service requirements. Early approaches used the k‐median and k‐center algorithms, which select k controllers to minimize propagation latency without considering network resilience. In this paper, we developed a new nodal metric, nodal disjoint path (NDP), which measures a node's importance in terms of its diverse connectivity to other nodes. Based on NDP, we propose two algorithms, NDP‐global and NDP‐cluster, for determining the locations of the k controllers to increase network robustness against targeted attacks. We apply the two selection algorithms to four US‐based fiber‐level networks and evaluate their resilience against five centrality‐based attacks and random failures. The evaluation results indicate that selecting controllers by the NDP‐global algorithm, compared with the NDP‐cluster, k‐median, and k‐center algorithms, provides better network resilience in the face of centrality‐based attacks and random failures. The results also indicate that the NDP‐cluster algorithm has a delay performance comparable to that of the k‐median algorithm and provides higher network resilience.