Distributed SDN controller placement using betweenness centrality & hierarchical clustering

Software-defined networking (SDN) separates the control plane from the data plane. This simplifies network management and provides flexibility to the network administrator. Such an architecture can be implemented in various types of networks including wide-area networks and vehicular networks. Two different approaches are possible for the control plane, namely the centralized controller approach and the distributed multiple controllers approach. For efficient network management in a large distributed network, the location and number of controllers should be optimized to provide the service providers desired system performance. This paper proposes a new framework that solves the SDN controller placement problem by combining both the hierarchical clustering and betweenness centrality concepts (denoted as HC-BC). The performance of the proposed framework is evaluated using a real-world network and compared to three other algorithms in terms of worst-case switch-to-controller latency and domain imbalance. The simulation results show that the proposed HC-BC framework achieves the best compromise between the latency and the domain imbalance between different clusters, with the added advantage of having lower computational complexity.