A source routing based link protection method for link failure in SDN

The link failure recovery process may introduce large delay and serious packet loss in SDN because the failure has to be handled by remote controller. In recent years, several link protection methods have been put forward to solving this problem using preplanned backup paths, and avoiding the involvement of remote controller. However, it may need large quantities of flow entries to build these backup paths and complex mechanism to keep them active, and may cause congestion during rerouting process. In order to solve these problems, this paper proposes a source routing based link protection method in SDN. With predefined backup paths for every link, our method uses source routing to control the flow's route and steers the packet into backup path through updating the source routing header when link failure happens. Through implementation and evaluation, it is shown that this method can significantly reduce the overhead to build and maintain backup paths because we store the route information in the packet's header instead of flow entries installed in switch. And with flexibly and dynamically backup path planning, this method can achieve better congestion avoidance in the backup path during rerouting process comparing to previous methods.