Lab 11 – TI-LFA Global Weighted SRLG Protection

The previous chapter explored TI-LFA SRLG protection in a local SRLG-disjoint scenario, where a router is aware only of the SRLGs of its local links. In situations where another link, not directly connected to the router, is part of the same SRLG and potentially along the backup path, the TI-LFA Local SRLG-disjoint protection method fails to exclude that link during the calculation of the post-convergence backup path. This can result in a backup path that fails simultaneously with the primary path, as the router unknowingly includes an SRLG from a remote route. This occurs because routers in the network lack information about each other’s SRLGs.

In a segment routing MPLS network, the link-state routing protocol (in this case, IS-IS), carries link-state information and propagates SRLG details as another TLV (Type-Length-Value), ensuring that all routers are aware of both local and remote SRLGs.

TI-LFA Global Weighted...