Summary
SRLG refers to a set of links on a router that share a common risk at the transmission layer, such as through shared fiber or transmission equipment.
This means that if one link fails due to an issue in that transmission medium, all links sharing it will also fail. If both the SR-MPLS primary path and the TI-LFA backup path utilize the same transmission medium, fast reroute mechanisms may not function properly.
The TI-LFA local SRLG-disjoint protection method resolves this issue by ensuring that the backup path avoids SRLG links.
In this lab, the P2-P3 and P2-P7 links were configured as part of the same SRLG named SRLG-100 and assigned an SRLG value of 100. This configuration informed the router P2 that these links shared the same risk.
On the router P2, SRLG protection was activated under the router’s IS-IS protocol similarly to node protection in the previous chapter, by assigning a non-zero index value of 100 to it.
The RIB, FIB, and LFIB outputs, along...
