Software-Defined Networking: The Impact of Scalability on Controller Performance

Software-Defined Networking (SDN) is a large-scale implementation networking paradigm that decouples the control plane from the forwarding plane. As the size of a network topology become larger, SDN suffers from various performance and scalability problems leading to important research efforts on maximizing the scalability of the control plane. One of the solutions would be the deployment of multi-controller SDN architecture. The impact of scalability on SDN control plane performance is mostly concerned with the number of controllers as well as the network topology model. Specifically, this paper aims to analyze the scalability of one of the most used SDN controllers in a specific multi-tier network environment with the various number of switches and hosts. An evaluation of the RYU controller performance in terms of throughput and delay is provided. We are focusing on providing the evaluation of the results of the analysis between single and multi-controller network topologies. By observing the experimental results, it can be concluded that the multi-controller topology better handles the network traffic as compared to the single-controller topology. Afterward, open research issues related to control plane scalability were also considered.