MPLS consists of 3 components: 1. MPLS forwarding 2. MPLS signalling 3. Mapping layer 3 traffic onto MPLS LSPs The document mpls-forwarding basics explains item 1. Examples of MPLS signalling protocols are: RSVP-TE LDP and CR-LDP. The package ldp-portable is an implementation of LDP and contains more information about LDP based MPLS signalling. Mapping of layer 3 traffic to MPLS LSPs is accomplised in a couple of different ways. -Per FEC where FEC is an entry in the routing table -Virtual interface that represents an LSP