Configuring LDP and an IGP to Transport Layer 2 Circuits
LDP is used as the signaling protocol to advertise the ingress MPLS label to the remote PE router. For this purpose, a remote LDP neighbor is established using the extended discovery mechanism described in RFC 5036, LDP Specification, and a session is established.
No new configuration is necessary in LDP because
the LDP protocol recognizes the Layer 2 circuit configuration
and initiates extended neighbor discovery for all Layer 2 circuit
neighbors on the remote PE routers. This is very similar to the behavior
of LDP when it is tunneled over RSVP. However, you must configure
LDP on the lo0.0 interface for extended neighbor discovery
to function correctly.
LDP relies on an underlying IGP, such as OSPF or IS-IS. Therefore, configure LDP and your IGP on all routers in the path from the local PE router to the remote PE router across the service provider backbone.
[edit]
protocols {
ospf {
traffic-engineering;
area 0.0.0.0 {
interface so-0/1/0.0;
interface lo0.0;
}
}
ldp {
interface so-0/1/0.0;
interface lo0.0;
}
}