Implementation of Topology Independent Loop Free Alternate with Segment Routing Traffic

Network failures have a huge impact on daily life and its restoration must be done at the earliest. The slow convergence time of configured routing protocols during the link failure becomes a concern and to overcome this problem various Fast Reroute (FRR) mechanisms are developed. FRR's key feature is fast failure detection and pre-calculation of an alternative path even before link or node fails. This precalculated alternative path bypasses the problem and restores communication in the event of a true network failure. In this paper Topology Independent Loop-free Alternate (TI-LFA), a Fast Re-route (FRR) technique is implemented with Segment Routing (SR). This implementation is carried out by creating different network topologies using CISCO IOS XRv routers in Cisco virtual lab environment. Firstly, the created topologies are configured with an IGP protocol, in this case it is configured with IS-IS protocol for routing functionality. This is followed by configuration of segment routing and TI-LFA on each of the individual routers. TI-LFA functionality is implemented for zero, single and double segment scenarios using different network topologies and it is verified by the labels imposed in each scenario. Shared Risk Link Group (SRLG) protection is also implemented and verified with the help of routing information base.