When setting up the FRR bypass or detour LSP, enable the srlg-frr option on FRR to ensure that CSPF includes the SRLG constraint in its route calculation. CSPF prunes all links that are in the SRLG being used by the primary LSP during the calculation of the FRR path. If one or more paths are found, CSPF sets up the FRR bypass or detour LSP based on the best cost and signals the FRR LSP.
If there is no path found based on the above calculation and the srlg-frr command has the strict option set, then the FRR LSP is not set up and the MPLS/RSVP-TE task keeps trying to set up a path. If the strict option is not set, then the FRR LSP is set up based on the other TE constraints (that is, excluding the SRLG constraint).