Topology Aware Evaluation of SDN Controller Performance and Placement Strategies in Star, Linear, and Ring Networks

Software-defined networking allows centralized and flexible control of a network, but its performance largely depends on the controller and its location in the network. The current work presents an experimental study of the Software-Defined Networking (SDN) controller performance considering various placement methods using star, linear, and ring topologies. Placement methods, including centrality-based, greedy, clustering, metaheuristic, capacitated, and baseline approaches, are analyzed with four popular controllers: Beacon, RYU, OpenDaylight, and Open Network Operating System (ONOS). Experiments are conducted using Mininet-based emulation, and findings indicate that controller performance varies based on location within the network. Among the evaluated techniques, the partition-based approach is identified as balanced controller placement in linear and ring topologies, given stable latency and throughput values comparable to other optimized strategies. Overall, the lowest latency is produced by RYU, the maximum throughput by OpenDaylight, and the intermediate performance by ONOS and Beacon.