An LFA SPF policy allows the user to apply specific criteria, such as admin group and SRLG constraints, to the selection of a LFA backup next-hop for a subset of prefixes that resolve to a specific primary next-hop. See more details in the Loop-Free Alternate Shortest Path First (LFA SPF) Policies section in the 7210 SAS-Mxp, R6, R12, S, Sx, T Routing Protocols Guide.