The Label Distribution Protocol (LDP) is a protocol for distributing labels in nontraffic-engineered applications. LDP allows routers to establish LSPs through a network by mapping network-layer routing information directly to data link layer-switched paths.
LDP is described in Label Distribution Protocol (LDP)—Version 1 Functional Specification, Internet draft draft-ietf-mpls-ldp-06.txt.
These LSPs might have an end point at a directly attached neighbor (comparable to IP hop-by-hop forwarding), or they might have an end point at a network egress node, enabling switching through all intermediary nodes. LSPs established by LDP can also traverse traffic-engineered LSPs created by RSVP.
LDP associates a set of destinations (route prefixes ...