QoSP: A Priority-Based Queueing Mechanism in Software-Defined Networking Environments

Software-defined networking (SDN) is an emerging networking technology and allows for a separation of data and control planes traffic in order to enhance the Quality of Service (QoS) for traffic and services delivery. Latency metric is regarded as a critical parameter by service providers and end users alike, where inter-link delays can be measured using end-to-end (E2E) probing packets. Moreover, to support latency-sensitive applications in SDN such as emergency response, we need a comprehensive QoS mechanism to ensure the minimization of E2E latency, the efficacious calculation of forwarding paths, and the minimization of control response time. We first distinguish between a flow's admission latency and a flow's packet forwarding latency. The former is decided by its controller's response time, and the latter by its data plane queue delay. We then design a two-queue system with feedback, named QoSP, that aims to control overall latency performance in SDN through improving data-control communication performance and imposing efficient queueing control. We specifically introduce a priority-based queueing discipline in the data plane to achieve differentiated QoS provisioning via maintaining multiple OpenFlow queues with different priorities at each switch port. We implement the proposed QoSP using a Floodlight SDN controller and conduct emulation studies on the Global Environment for Networking Innovations. Our evaluation shows that QoSP can optimize the E2E delay and significantly reduce the control response time for priority traffic.