Selecting shorter alternate paths for tunnel-based IP Fast ReRoute in linear time

IP Fast ReRoute (IPFRR) has received increasing attention as a means to effectively shorten traffic disruption under failures. A major approach to implementing IPFRR is to pre-calculate backup paths for nodes and links. However, it may not be easy to deploy such an approach in practice due to the tremendous computational overhead. Thus, a light-weight IPFRR scheme is desired to effectively provide cost-efficient routing protection. In this paper, we propose a Fast Tunnel Selection (FTS) approach to achieve tunnel-based IPFRR. FTS approach can find an effective tunnel endpoint before complete computation of entire SPT and thus effectively reduce computation overhead. Specially, we propose two FTS algorithms to provide protection for networks with symmetric and asymmetric link weights. We simulate FTS with topologies of different sizes. The results show that FTS approach reduces more than 89% computation overhead compared to the existing approaches, and achieves more than 99% average link protection rate and more than 90% average node protection rate. Moreover, FTS approach achieves less than 15% path stretch, which is better than the existing approaches.