LDP Applicability
Bob Thomas, Eric Gray · 2001
Multiprotocol Label Switching (MPLS) is a method for forwarding packets that uses short, fixed-length values carried by packets, called labels, to determine packet nexthops.A fundamental concept in MPLS is that two Label Switching Routers (LSRs) must agree on the meaning of the labels used to forward traffic between and through them.This common understanding is achieved by using a set of procedures, called a label distribution protocol, by which one LSR informs another of label bindings it has made.This document describes the applicability of a set of such procedures called LDP (for Label Distribution Protocol) by which LSRs distribute labels to support MPLS forwarding along normally routed paths. LDP ApplicabilityA label distribution protocol is a set of procedures by which one Label Switching Router (LSR) informs another of the meaning of labels used to forward traffic between and through them.The MPLS architecture allows for the possibility of more than a single method for distributing labels, and a number of different label distribution protocols are being standardized.Existing protocols have been extended so that label distribution can be piggybacked on them, and new protocols have been defined for the explicit purpose of distributing labels.