For the LDP shortcut to be usable, SR OS must originate a <FEC, label> binding for each IGP route it learns of even if it did not receive a binding from the next-hop for that route. The router must assume that it is an egress LER for the FEC until the route disappears from the routing table or the next-hop advertises a binding for the FEC prefix. In the latter case, SR OS becomes a transit LSR for the FEC.
SR OS originates a <FEC, label> binding for its system interface address only by default. The only way to originate a binding for local interfaces and routes that are not local to the system is by using the fec-originate capability.
Use the fec-originate command to generate bindings for all non-local routes for which this node acts as an egress LER for the corresponding LDP FEC. Specifically, this feature must support the FEC origination of IGP learned routes and subscriber/host routes statically configured or dynamically learned over subscriber IES interfaces.
An LDP LSP used as a shortcut by IPv4 packets may also be tunneled using the LDP-over-RSVP feature.