Topology-driven performance insights

Abstract

Software-Defined Networking (SDN) transforms traditional network design by decoupling the control and data planes, enabling centralized programmability, scalability, and dynamic reconfiguration. This paper presents a QoS-driven performance analysis of two popular SDN controllers, Ryu and ONOS, combined with Dijkstra and Multipath routing algorithms in scalable Fat-Tree topologies ( k = 4–10). Experiments were conducted in Mininet (OpenFlow 1.3) using iPerf with TCP and UDP traffic, each repeated 100 independent runs for statistical confidence. Key QoS metrics including throughput, jitter, round-trip time (RTT), packet loss ratio (PLR), CPU utilization, flow setup time, and scalability were evaluated. The results show that ONOS-Multipath achieved the highest average TCP throughput (up to 3.58 Gbps), with the lowest jitter, minimal PLR, and maximum host scalability (up to 250 hosts at k = 10). Compared with earlier POX- and Floodlight-based benchmarks, the ONOS-Multipath setup improves throughput by approximately 20 percent and reduces packet loss by up to 80 percent, confirming that the controller architecture critically shapes routing efficiency and that ONOS + Multipath provides the most robust and scalable SDN configuration for large-scale deployments.