QoS-Guaranteed Controller Placement in SDN

The controller placement problem tries to place $k$ controllers in a given network to optimize performance metrics such as propagation latency, load distribution, network reliability and failure resilience. However, the quality of service (QoS) is always a primary concern of the network operators in the placement of SDN controllers. Since the SDN controllers are responsible to provide services for switches, the response time of controllers is an important QoS parameter of network operators. In this paper, we introduce the QoS-Guaranteed Controller Placement problem: Given a network topology and a response time bound, how many controllers are needed, where to place them, and which switches are assigned to each of the controller. We propose three heuristic algorithms: incremental greedy algorithm, primal-dual-based algorithm and network-partition-based algorithm. The proposed algorithms are tested and compared on the Internet Topology Zoo, a dataset of public available network topologies. Simulation results show that the proposed incremental greedy method slightly outperforms the other two methods on all input topologies.