At the Point of Local Repair (PLR), when multiple leaves are reachable through the same next-hop, all the leaves must be protected through the same protection next-hop.
For example, in Figure 1, from the point of view of A, both D and E are reachable through C. C is the next-hop for both D and E and can have a single protection next-hop, either B or F. If B is chosen as the protection next hop, for an LFA, the packet is forwarded to B for both D and E. B is not on the Shortest Path First (SPF) path to E and not the correct LFA, so an LFA for F is not possible in this network topology.
Figure 1. Topology example 1
If the network topology is changed as shown in Figure 2, B can protect both D and E.
Figure 2. Topology example 2
