Topology Independent Fast Reroute using Segment Routing

Abstract

This document presents Topology Independent Loop-free Alternate Fast Re-route (TI-LFA), aimed at providing link and node protection of node and adjacency segments within the Segment Routing (SR) framework. This Fast Re-route (FRR) behavior builds on proven IP-FRR concepts being LFAs, remote LFAs (RLFA), and remote LFAs with directed forwarding (DLFA). It extends these concepts to provide guaranteed coverage in any IGP network. We accommodate the FRR discovery and selection approaches in order to establish protection over post-convergence paths from the point of local repair, dramatically reducing the operational need to control the tie-breaks among various FRR options.