Interaction with LDP Shortcut for Static Route Resolution
There is no interaction between LDP shortcut for static route resolution and the LDP shortcut for
IGP route resolution. A static route will continue to be resolved by searching an LDP LSP which
FEC prefix matches the specified indirect next-hop for the route. In contrast, the LDP shortcut for
IGP route resolution uses the LDP LSP as a route.
LDP Control Plane
In order for the LDP shortcut to be usable, an SR-OS router 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.
In other words, it must assume it is an egress LER for the FEC until the route disappears from the
routing table or the next-hop advertised a binding for the FEC prefix. In the latter case, the SR-OS
router becomes a transit LSR for the FEC.
An SR-OS router will originate a <FEC, label> binding for its system interface address only by
default. The only way to originate a binding for local interfaces and routes which are not local to
the system is by using the fec-originate capability.
You must 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.
7710 SR OS Router Configuration Guide
IP Router Configuration
Page 83