EIGRP what happens when a feasible successor fails

If a feasible successor fails, the route will go active in the EIGRP topology table. This is because the FSM is performing calculations to determine if there is an alternative feasible successor.

However, because there is already a successor installed in the routing table, this successor remains there. For this reason, in such a scenario, there is no downtime in routing.

EIGRP SIA timers

Links: https://learningnetwork.cisco.com/s/question/0D53i00000Kt0mg/feasible-successor-route-in-the-topology-database-does-not-guarantee-that-the-router-wont-go-active-on-the-route