Configuring LDP for Layer 2 Circuits
Use LDP as the signaling protocol to advertise ingress labels to the remote PE routers. When configured, LDP examines the Layer 2 circuit configuration and initiates extended neighbor discovery for all the Layer 2 circuit neighbors (for example, remote PEs). This process is similar to how LDP works when tunneled over RSVP. You must run LDP on the lo0.0 interface for extended neighbor discovery to function correctly.
For detailed information about how to configure LDP, see the MPLS Applications User Guide.