-LDP is a control driven MPLS signaling protocol which means labels are distributed according to changes in L3 topology, not in response to data flows.-LDP only assignes and receives mappings which are in turn fed to the MPLS forwarding plane.  LDP does not participate in the actual labelling of packets.  Labeling of packets is part of the MPLS forwarding plane. See 'mpls-linux' for an implementation of MPLS forwarding.-LDP has a few modes of operation: Distribution Mode - Unsolicited vs On Demand Control Mode - Independent vs Ordered Repair Mode - Local vs Global-LDP genrates or requests labels for each FEC.  A FEC is defined as an entry in the L3 forwarding table.