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LDP Specification (RFC3036)

IP.com Disclosure Number: IPCOM000005228D
Original Publication Date: 2001-Jan-01
Included in the Prior Art Database: 2001-Aug-17

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

L. Andersson: AUTHOR [+5]

Abstract

The architecture for Multi Protocol Label Switching (MPLS) is described in RFC 3031. 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 defines a set of such procedures called LDP (for Label Distribution Protocol) by which LSRs distribute labels to support MPLS forwarding along normally routed paths.

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Network Working Group L. Andersson Request for Comments: 3036 Nortel Networks Inc. Category: Standards Track P. Doolan Ennovate Networks N. Feldman

IBM Corp

A. Fredette PhotonEx Corp

B. Thomas Cisco Systems, Inc.

January 2001

LDP Specification

Status of this Memo

This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (2001). All Rights Reserved.

Abstract

The architecture for Multi Protocol Label Switching (MPLS) is described in RFC 3031. 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 defines a set of such procedures called LDP (for Label Distribution Protocol) by which LSRs distribute labels to support MPLS forwarding along normally routed paths.

Andersson, et al. Standards Track [Page 1]

RFC 3036 LDP Specification January 2001

Table of Contents

1 LDP Overview ....................................... 5 1.1 LDP Peers .......................................... 6 1.2 LDP Message Exchange ............................... 6 1.3 LDP Message Structure .............................. 7 1.4 LDP Error Handling ................................. 7 1.5 LDP Extensibility and Future Compatibility ......... 7 1.6 Specification Language ............................. 7 2 LDP Operation ...................................... 8 2.1 FECs ............................................... 8 2.2 Label Spaces, Identifiers, Sessions and Transport .. 9 2.2.1 Label Spaces ....................................... 9 2.2.2 LDP Identifiers .................................... 10 2.2.3 LDP Sessions ....................................... 10 2.2.4 LDP Transport ...................................... 11 2.3 LDP Sessions between non-Directly Connected LSRs ... 11 2.4 LDP Discovery ..................................... 11 2.4.1 Basic Discovery Mechanism .......................... 12 2.4.2 Extended Discovery Mechanism ....................... 12 2.5 Establishing and Maintaining LDP Sessions .......... 13 2.5.1 LDP Session Establishment .......................... 13 2.5.2 Transport Connection Establishment ................. 13 2.5.3 Session Initialization ............................. 14 2.5.4 Initialization State Machine ....................... 17 2.5.5 Maintaining Hello Adjacencies ...................... 20 2.5.6 Maintaining LDP Sessions .......