Configuration
To create the ring topology in Figure 7.1, the links toward P2, P3, and P4 must be shut down on router P7.
The interfaces can be shut down under the IS-IS context, as shown in the following. This action would trigger an IS-IS update from router P7, withdrawing the link state information for those links and excluding them from the active topology.
P7
router isis IGP interface GigabitEthernet0/0/0/1 shutdown ! interface GigabitEthernet0/0/0/3 shutdown ! interface GigabitEthernet0/0/0/4 shutdown
As visually evident from Figure 7.1, after shutting down the specified links, the primary path from P2 to PE5 is via P3 due to the lower end-to-end path cost. The next step is to verify whether TI-LFA was able to offer a backup path, as described in the following section.
