Making Route Flap Damping Usable
RFC 7196

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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.

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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

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RFC 7196            Making Route Flap Damping Usable            May 2014

   the prefixes were responsible for 36% percent of the BGP messages at
   a router with real feeds from a Tier-1 provider and an Internet