LDP Specification
RFC 5036
Document | Type |
RFC - Draft Standard
(October 2007; Errata)
Obsoletes RFC 3036
|
|
---|---|---|---|
Authors | Bob Thomas , Loa Andersson , Ina Minei | ||
Last updated | 2020-01-21 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized with errata bibtex | ||
Stream | WG state | WG Document | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 5036 (Draft Standard) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Bill Fenner | ||
Send notices to | (None) |
Network Working Group L. Andersson, Ed. Request for Comments: 5036 Acreo AB Obsoletes: 3036 I. Minei, Ed. Category: Standards Track Juniper Networks B. Thomas, Ed. Cisco Systems, Inc. October 2007 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. Abstract The architecture for Multiprotocol 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. 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 .....................................9 2.2.3. LDP Sessions .......................................10 2.2.4. LDP Transport ......................................10 Andersson, et al. Standards Track [Page 1] RFC 5036 LDP Specification October 2007 2.3. LDP Sessions between Non-Directly Connected LSRs ..........10 2.4. LDP Discovery .............................................11 2.4.1. Basic Discovery Mechanism ..........................11 2.4.2. Extended Discovery Mechanism .......................11 2.5. Establishing and Maintaining LDP Sessions .................12 2.5.1. LDP Session Establishment ..........................12 2.5.2. Transport Connection Establishment .................12 2.5.3. Session Initialization .............................14 2.5.4. Initialization State Machine .......................16 2.5.5. Maintaining Hello Adjacencies ......................19 2.5.6. Maintaining LDP Sessions ...........................19 2.6. Label Distribution and Management .........................20 2.6.1. Label Distribution Control Mode ....................20 2.6.1.1. Independent Label Distribution Control ....20 2.6.1.2. Ordered Label Distribution Control ........20 2.6.2. Label Retention Mode ...............................21 2.6.2.1. Conservative Label Retention Mode .........21 2.6.2.2. Liberal Label Retention Mode ..............21 2.6.3. Label Advertisement Mode ...........................22 2.7. LDP Identifiers and Next Hop Addresses ....................22 2.8. Loop Detection ............................................23 2.8.1. Label Request Message ..............................23 2.8.2. Label Mapping Message ..............................25 2.8.3. Discussion .........................................26 2.9. Authenticity and Integrity of LDP Messages ................27 2.9.1. TCP MD5 Signature Option ...........................27 2.9.2. LDP Use of TCP MD5 Signature Option ................29 2.10. Label Distribution for Explicitly Routed LSPs ............29 3. Protocol Specification .........................................30 3.1. LDP PDUs ..................................................30 3.2. LDP Procedures ............................................31Show full document text