Buffer Size Evaluation of OpenFlow Systems in Software-Defined Networks

In this paper, we address the problem of minimum buffer size evaluation of an OpenFlow system in software-defined networks (SDNs), while ensuring optimum packet waiting time. The problem is important, as OpenFlow is one of the popular southbound application programing interfaces, which enables controller–switch interaction. The related existing literature addresses schemes on enhancement and packet flow in an OpenFlow system. However, there is a need to analyze the optimum buffer size of an OpenFlow switch, for ensuring the quality-of-service of SDNs. In this paper, we propose an analytical scheme for buffer bound evaluation of an OpenFlow system, named OPUS. Additionally, we propose a queuing scheme for an OpenFlow system—C-M/M/1/K/$\infty$ queuing model—based on the OpenFlow specification version 1.5.0. Further, we calculate the minimum buffer size requirement of an OpenFlow switch, theoretically. Simulation-based analysis exhibits that with two times increase in packet processing rate, the packet arrival rate can be increased by 26.15–$\text{30.4}\%$. We infer that for an OpenFlow system, the minimum buffer size is 0.75 million packets with the maximum packet arrival and the minimum processing rate of 0.20–0.25 million packets per second (mpps) and 0.03–0.35 mpps, respectively, and the maximum packet waiting time is 0.173–0.249 s.