Label Distribution Protocol

In the Label Distribution Protocol ( LDP) is a signaling protocol for establishing a connection via Label Switched Path (LSP ) in MPLS networks.

The protocol is used to negotiate labels and the corresponding forwarding classes between two Label Switch Routers ( LSR) or between a Label Switch Router Label Edge Router and a ( LER ).

Each LSR in an MPLS network periodically sends Hello packets over UDP port 646 as broadcast messages to all routers on the same subnet in order to make themselves known on the net.

LDP sessions are established for bi-directional communication over TCP port 646 to exchange MPLS labels between them -knowing LSRs and get to know each forwarding class of the other router

LDP is scalable and can be easily extended.

The protocol is standardized by the IETF and first published in RFC 3036. The current specification is given in RFC 5036th

  • Network protocol at the application layer
Forwarding Equivalence Class Bidirectional (disambiguation) Internet Engineering Task Force
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