TOR-ME: Reducing Controller Response Time Based on Rings in Software Defined Networks

In a software defined network (SDN), switches will send Packet-In messages of newly arrived flows to the controllers. With more and more flows arriving at a network, the controller load significantly increases, which may lead to control channel congestion and long controller response time. Meanwhile, to the best of our knowledge, part of these flows are elephant flows that can affect system performance (including control plane and data plane). To address this challenge, in this paper, we propose a novel Time-Optimized Ring with Minimizing Elephant flow (TOR-ME) scheme and present several algorithms for it. Our evaluation shows that TOR-ME can reduce controller response time by 54.8%, and improve the network throughput by 58.1%, when comparing with the existing solutions.