Making Route Flap Damping Usable
RFC 7196
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(May 2014; Errata)
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2015-10-14
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(last changed 2013-08-21)
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RFC 7196 (Proposed Standard)
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Internet Engineering Task Force (IETF) C. Pelsser
Request for Comments: 7196 R. Bush
Category: Standards Track Internet Initiative Japan
ISSN: 2070-1721 K. Patel
Cisco Systems
P. Mohapatra
Sproute Networks
O. Maennel
Loughborough University
May 2014
Making Route Flap Damping Usable
Abstract
Route Flap Damping (RFD) was first proposed to reduce BGP churn in
routers. Unfortunately, RFD was found to severely penalize sites for
being well connected because topological richness amplifies the
number of update messages exchanged. Many operators have turned RFD
off. Based on experimental measurement, this document recommends
adjusting a few RFD algorithmic constants and limits in order to
reduce the high risks with RFD. The result is damping a non-trivial
amount of long-term churn without penalizing well-behaved prefixes'
normal convergence process.
Status of This Memo
This is an Internet Standards Track document.
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). Further information on
Internet Standards is available in 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/rfc7196.
Pelsser, et al. Standards Track [Page 1]
RFC 7196 Making Route Flap Damping Usable May 2014
Copyright Notice
Copyright (c) 2014 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
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
1.1. Suggested Reading . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. RFD Parameters . . . . . . . . . . . . . . . . . . . . . . . 3
4. Suppress Threshold versus Churn . . . . . . . . . . . . . . . 4
5. Maximum Penalty . . . . . . . . . . . . . . . . . . . . . . . 4
6. Recommendations . . . . . . . . . . . . . . . . . . . . . . . 5
7. Security Considerations . . . . . . . . . . . . . . . . . . . 5
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
9.1. Normative References . . . . . . . . . . . . . . . . . . 6
9.2. Informative References . . . . . . . . . . . . . . . . . 6
1. Introduction
Route Flap Damping (RFD) was first proposed (see [RIPE178] and
[RFC2439]) and subsequently implemented to reduce BGP churn in
routers. Unfortunately, RFD was found to severely penalize sites for
being well connected because topological richness amplifies the
number of update messages exchanged, see [MAO2002]. Subsequently,
many operators turned RFD off; see [RIPE378]. Based on the
measurements of [PELSSER2011], [RIPE580] now recommends that RFD is
usable with some changes to the parameters. Based on the same
measurements, this document recommends adjusting a few RFD
algorithmic constants and limits. The result is damping of a non-
trivial amount of long-term churn without penalizing well-behaved
prefixes' normal convergence process.
Very few prefixes are responsible for a large amount of the BGP
messages received by a router; see [HUSTON2006] and [PELSSER2011].
For example, the measurements in [PELSSER2011] showed that only 3% of
Pelsser, et al. Standards Track [Page 2]
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