LDP IGP Synchronization for Broadcast Networks
RFC 6138
| Document | Type |
RFC - Informational
(February 2011; No errata)
Updates RFC 5443
|
|
|---|---|---|---|
| Last updated | 2015-10-14 | ||
| Replaces | draft-lu-ldp-igp-sync-bcast | ||
| Stream | IETF | ||
| Formats | plain text pdf html bibtex | ||
| Stream | WG state | WG Document | |
| Document shepherd | No shepherd assigned | ||
| IESG | IESG state | RFC 6138 (Informational) | |
| Consensus Boilerplate | Unknown | ||
| Telechat date | |||
| Responsible AD | Adrian Farrel | ||
| Send notices to | martin.vigoureux@alcatel-lucent.com | ||
Internet Engineering Task Force (IETF) S. Kini, Ed.
Request for Comments: 6138 W. Lu, Ed.
Updates: 5443 Ericsson
Category: Informational February 2011
ISSN: 2070-1721
LDP IGP Synchronization for Broadcast Networks
Abstract
RFC 5443 describes a mechanism to achieve LDP IGP synchronization to
prevent black-holing traffic (e.g., VPN) when an Interior Gateway
Protocol (IGP) is operational on a link but Label Distribution
Protocol (LDP) is not. If this mechanism is applied to broadcast
links that have more than one LDP peer, the metric increase procedure
can only be applied to the link as a whole but not to an individual
peer. When a new LDP peer comes up on a broadcast network, this can
result in loss of traffic through other established peers on that
network. This document describes a mechanism to address that use-
case without dropping traffic. The mechanism does not introduce any
protocol message changes.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6138.
Copyright Notice
Copyright (c) 2011 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
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
Kini & Lu Informational [Page 1]
RFC 6138 LDP IGP Sync for Broadcast Networks February 2011
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction ....................................................2
2. Conventions Used in This Document ...............................2
3. Problem Statement ...............................................2
4. Solution ........................................................4
5. Scope ...........................................................5
6. Applicability ...................................................5
7. Security Considerations .........................................6
8. Conclusions .....................................................6
9. References ......................................................7
9.1. Normative References .......................................7
9.2. Informative References .....................................7
Acknowledgments ....................................................7
Appendix A. Computation of "Cut-Edge" ..............................8
Appendix B. Sync without Support at One End ........................8
1. Introduction
In RFC 5443 [LDP-IGP-SYNC], when [LDP] is not fully operational on a
link, the IGP advertises the link with maximum cost to avoid any
transit traffic on the link if possible. When LDP becomes
operational, i.e., all the label bindings have been exchanged, the
link is advertised with its correct cost. This tries to ensure that
the LDP Label Switch Path (LSP) is available all along the IGP
shortest path. The mechanisms in [LDP-IGP-SYNC] have limitations
when applied to a broadcast link. These are described in Section 3.
A solution is defined in Section 4.
2. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
3. Problem Statement
On broadcast networks, a router's Link State Advertisement (LSA)
contains a single cost to the broadcast network rather than a
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