Enhanced Topology Independent Loop-free Alternate Fast Re-route

Topology Independent Loop-free Alternate Fast Re-route (TI-LFA) aims at providing protection of node and adjacency segments within the Segment Routing (SR) framework. A key aspect of TI-LFA is the FRR path selection approach establishing protection over the expected post-convergence paths from the point of local repair. However, the TI-LFA FRR path may skip the node even if it is specified in the SID list to be traveled. This document defines Enhanced TI-LFA(TI-LFA+) by adding a No-bypass indicator for segments to ensure that the FRR route will not bypass the specific node, such as firewall. Also, this document defines No- bypass flag and No-FRR flag in SRH to indicate not to bypass nodes and not to perform FRR on all the nodes along the SRv6 path, respectively.