LDP IGP Synchronization
RFC 5443
Document | Type |
RFC - Informational
(March 2009; No errata)
Updated by RFC 6138
|
|
---|---|---|---|
Authors | Markus Jork , Alia Atlas , Luyuan Fang | ||
Last updated | 2020-07-29 | ||
Replaces | draft-ietf-mpls-igp-sync | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Reviews | |||
Stream | WG state | WG Document | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 5443 (Informational) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | David Ward | ||
Send notices to | rcallcon@juniper.net, isis-chairs@ietf.org |
Network Working Group M. Jork Request for Comments: 5443 GENBAND Category: Informational A. Atlas British Telecom L. Fang Cisco Systems, Inc. March 2009 LDP IGP Synchronization Status of This Memo This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited. Copyright Notice Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Jork, et al. Informational [Page 1] RFC 5443 LDP IGP Synchronization March 2009 Abstract In certain networks, there is dependency on the edge-to-edge Label Switched Paths (LSPs) setup by the Label Distribution Protocol (LDP), e.g., networks that are used for Multiprotocol Label Switching (MPLS) Virtual Private Network (VPN) applications. For such applications, it is not possible to rely on Internet Protocol (IP) forwarding if the MPLS LSP is not operating appropriately. Blackholing of labeled traffic can occur in situations where the Interior Gateway Protocol (IGP) is operational on a link on which LDP is not. While the link could still be used for IP forwarding, it is not useful for MPLS forwarding, for example, MPLS VPN applications or Border Gateway Protocol (BGP) route-free cores. This document describes a mechanism to avoid traffic loss due to this condition without introducing any protocol changes. Table of Contents 1. Introduction ....................................................2 1.1. Conventions Used in This Document ..........................3 2. Proposed Solution ...............................................3 3. Applicability ...................................................4 4. Interaction with TE Tunnels .....................................5 5. Security Considerations .........................................5 6. References ......................................................6 6.1. Normative References .......................................6 6.2. Informative References .....................................6 7. Acknowledgments .................................................6 1. Introduction LDP [RFC5036] establishes MPLS LSPs along the shortest path to a destination as determined by IP forwarding. In a common network design, LDP is used to provide Label Switched Paths throughout the complete network domain covered by an IGP such as Open Shortest Path First (OSPF) [RFC2328] or Intermediate System to Intermediate System (IS-IS) [ISO.10589.1992]; i.e., all links in the domain have IGP as well as LDP adjacencies. A variety of services a network provider may want to deploy over an LDP-enabled network depend on the availability of edge-to-edge label switched paths. In a layer 2 (L2) or layer 3 (L3) VPN scenario, for example, a given Provider-Edge (PE) router relies on the availability of a complete MPLS forwarding path to the other PE routers for the VPNs it serves. This means that all the links along the IP shortest path from one PE router to the other need to have operational LDP sessions, and the necessary label binding must have been exchanged over those sessions. If only one link along the IP shortest path is Jork, et al. Informational [Page 2] RFC 5443 LDP IGP Synchronization March 2009 not covered by an LDP session, a blackhole exists and servicesShow full document text