When both IGP shortcut and LFA are enabled in IS-IS or OSPF, and IP FRR is also enabled, then the following additional IP FRR capabilities are supported:
A prefix which is resolved to a direct primary next-hop can be backed up by a tunneled LFA next-hop.
A prefix which is resolved to a tunneled primary next-hop will not have an LFA next-hop. It will rely on RSVP FRR for protection.
The LFA SPF is extended to use IGP shortcuts as LFA next-hops as described in OSPF and IS-IS support for Loop-Free Alternate calculation.