A Scalability Metric for Control Planes in Software Defined Networks (SDNs)

Abstract

Software Defined Networking (SDN) architecture promises to mitigate limitations of traditional networking architectures in order to satisfy today's complex networking needs. However, as all new networking architectures, SDN also presents several inevitable technical challenges to be addressed by researchers. Control plane scalability is one of the crucial issues deserving more attention from both academia and industry in SDN as well. There are many existing solutions proposing a way to alleviate the control plane scalability in SDN. However, one prominent common ground they share is that they measure the control plane scalability performance in terms of typical network QoS parameters such as throughput and latency. Although these metrics may be a good performance indicators for quality of service measurement in mid-term and long-term, they may not reflect real scalability performance of control planes in SDN environments. However, a metric for scalability of control plane in SDN can provide network administrators some insights while they construct their SDN networks. In this paper, we firstly explore the roots of control plane scalability problem in SDN as well as proposed existing solutions. We then propose a metric in order to evaluate the control plane scalability in SDN. We give mathematical models of the proposed metric over different control plane designs. Further, we compare the performance of these control plane designs by extensive experiments.