The MPLS facility bypass method of MPLS Fast Re-Route (FRR) functionality is extended to the ingress node.
The behavior of an LSP at an ingress LER with both fast reroute and a standby LSP path configured is as follows:
when a downstream detour becomes active at a point of local repair (PLR)
The ingress LER switches to the standby LSP path. If the primary LSP path is repaired subsequently at the PLR, the LSP switches back to the primary path. If the standby goes down, the LSP is switched back to the primary, even though it is still on the detour at the PLR. If the primary goes down at the ingress while the LSP is on the standby, the detour at the ingress is cleaned up and for one-to-one detours a ‟path tear” is sent for the detour path. In other words, the detour at the ingress does not protect the standby. If and when the primary LSP is again successfully re-signaled, the ingress detour state machine is restarted.
when the primary fails at the ingress
The LSP switches to the detour path. If a standby is available then LSP would switch to standby on expiration of hold-timer. If hold-timer is disabled then switchover to standby would happen immediately. On successful global revert of primary path, the LSP would switch back to the primary path.