SoftRing: Taming the reactive model for software defined networks

The reactive model of Software Defined Networking (SDN) invokes controller to dynamically determine the behaviors of a new flow without any pre-knowledge in the data plane. However, the reactive events raised by such flexible model meanwhile consume lots of the bottleneck resources of the fast memory in switch and bandwidth between controller and switches. To address this problem, we propose SoftRing with the motivation to mitigate the overhead to handle a reactive event. In fact, the reactive packets are not necessarily stored in the switch or sent to the controller; instead, they are forwarded to traverse a pre-defined loop path. The packets will finally leave the loop path after the switch rules related to the packet flow being updated to switches in the loop with fewer flow entries. We have implemented a SoftRing system that integrates the controller and software/hardware SDN switches. The results show that SoftRing can eliminate the fast memory requirement for reactive packets and reduce the control channel bandwidth consumption up to 80%, with the cost of less than 5% data plane bandwidth, an average of three extra flow entries in each switch, and minor extra latency for the flow forwarding.