CAFFE: Congestion-Aware Fast Failure Recovery in Software Defined Networks

A logically centralized controller of Software Defined Networking (SDN) is responsible for the management of routing planning and monitoring of network status. With this central control and global visibility, in this paper, we propose a congestion-aware fast failure recovery scheme (CAFFE), which can not only recover the affected flows fast from a wide range of failure scenarios but also avoid potential congestion in the post-recovery network. CAFFE achieves fast recovery by detouring the traffic from neighbour switches as soon as they detect failures and avoids potential congestion by protected paths constructed with the combined consideration of the knowledge of network topology, failure states and network load distribution. We formulate and solve the protected path planning problems where all potential network failures should be protected and the maximum link load in the post-recovery network should be minimized. The resulting protected paths ensure high traffic reachability and low link load even when network failure happens. All these paths are set up a priori by CAFFE. This allows switches to handle failures automatically without the need on waiting for the response from the controller. Experimental results show that CAFFE achieves fast recovery with relatively low overheads on either switches (in terms of backup rule number to configure) or controller (in terms of computational time). It also shows that CAFFE is able to better load-balance the post-recovery network comparing to shortest path re-calculation and OpenFlow-based Segment Protection (OSP).