Objective

The objective of this chapter is to introduce TI-LFA in the SR-MPLS network topology in Figure 5.1. It will involve verifying the availability of backup paths and understanding how they are calculated and installed in the routers. These goals are accomplished through the following tasks:

1. Configuring TI-LFA on all IS-IS connections for every router.
2. Verifying that TI-LFA is operationally enabled.
3. Verifying that the TI-LFA backup route is computed and added to the RIB, FIB, and LFIB.
4. Understanding the methods to calculate backup paths.

TI-LFA will be enabled on all routers within the SR-MPLS network topology, illustrated in Figure 5.1.

Figure 5.1 – The TI-LFA base topology

Note

For all upcoming labs in the book, P2 will serve as the Point of Local Repair (PLR) due to its resilient and redundant multiple paths in the core, ensuring robust forwarding of traffic from PE1 to PE5.

Before diving into the lab work...