This is the maximum number of hops the detour LSP is permitted to traverse. Setting it too tight can leave FRR path computation unable to find any valid detour in a sparsely connected topology, while leaving it very high risks a detour that adds significant latency by looping through many extra routers before rejoining the primary path. For example, a hop limit of 3 forces the detour to rejoin the primary path within 3 hops of the failure point, which works in a dense core but would fail to find a valid path on a thin access ring.