3.5.h [iii] IP FRR/fast reroute [single hop]
The EIGRP Loop-Free Alternate Fast Reroute feature allows the Enhanced Interior Gateway Routing Protocol (EIGRP) to reduce the routing transition time to less than 50 ms by pre-computing repair paths or backup routes and installing these paths or routes in the Routing Information Base (RIB). Fast Reroute (FRR) is the mechanism that enables traffic that traverses a failed link to be rerouted around the failure. In EIGRP networks, pre-computed backup routes or repair paths are known as feasible successors or loop-free alternates (LFAs).
Adam, Paul (2014-07-12). All-in-One CCIE V5 Written Exam Guide (Kindle Locations 3274-3277). . Kindle Edition.