draft-ietf-idr-rfd-usable-03.txt   draft-ietf-idr-rfd-usable-04.txt 
Network Working Group C. Pelsser Network Working Group C. Pelsser
Internet-Draft R. Bush Internet-Draft R. Bush
Intended status: Standards Track Internet Initiative Japan Intended status: Standards Track Internet Initiative Japan
Expires: February 23, 2014 K. Patel Expires: April 14, 2014 K. Patel
P. Mohapatra
Cisco Systems Cisco Systems
P. Mohapatra
Cumulus Systems, Inc.
O. Maennel O. Maennel
Loughborough University Loughborough University
August 22, 2013 October 11, 2013
Making Route Flap Damping Usable Making Route Flap Damping Usable
draft-ietf-idr-rfd-usable-03 draft-ietf-idr-rfd-usable-04
Abstract Abstract
Route Flap Damping (RFD) was first proposed to reduce BGP churn in Route Flap Damping (RFD) was first proposed to reduce BGP churn in
routers. Unfortunately, RFD was found to severely penalize sites for routers. Unfortunately, RFD was found to severely penalize sites for
being well-connected because topological richness amplifies the being well-connected because topological richness amplifies the
number of update messages exchanged. Many operators have turned RFD number of update messages exchanged. Many operators have turned RFD
off. Based on experimental measurement, this document recommends off. Based on experimental measurement, this document recommends
adjusting a few RFD algorithmic constants and limits, to reduce the adjusting a few RFD algorithmic constants and limits, to reduce the
high risks with RFD, with the result being damping a non-trivial high risks with RFD, with the result being damping a non-trivial
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 23, 2014.
This Internet-Draft will expire on April 14, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Suggested Reading . . . . . . . . . . . . . . . . . . . . . . 2 1. Suggested Reading . . . . . . . . . . . . . . . . . . . . . . 2
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
3. RFD Parameters . . . . . . . . . . . . . . . . . . . . . . . 3 3. RFD Parameters . . . . . . . . . . . . . . . . . . . . . . . 3
4. Suppress Threshold Versus Churn . . . . . . . . . . . . . . . 3 4. Suppress Threshold Versus Churn . . . . . . . . . . . . . . . 4
5. Maximum Penalty . . . . . . . . . . . . . . . . . . . . . . . 4 5. Maximum Penalty . . . . . . . . . . . . . . . . . . . . . . . 4
6. Recommendations . . . . . . . . . . . . . . . . . . . . . . . 4 6. Recommendations . . . . . . . . . . . . . . . . . . . . . . . 5
7. Security Considerations . . . . . . . . . . . . . . . . . . . 5 7. Security Considerations . . . . . . . . . . . . . . . . . . . 5
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
10.1. Normative References . . . . . . . . . . . . . . . . . . 5 10.1. Normative References . . . . . . . . . . . . . . . . . . 5
10.2. Informative References . . . . . . . . . . . . . . . . . 6 10.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Suggested Reading 1. Suggested Reading
It is assumed that the reader understands BGP, [RFC4271] and Route It is assumed that the reader understands BGP, [RFC4271] and Route
Flap Damping, [RFC2439]. This work is based on the measurements in Flap Damping, [RFC2439]. This work is based on the measurements in
the paper [pelsser2011]. A survey of Japanese operators' use of RFD the paper [pelsser2011]. A survey of Japanese operators' use of RFD
and their desires is reported in and their desires is reported in
[I-D.shishio-grow-isp-rfd-implement-survey]. [I-D.shishio-grow-isp-rfd-implement-survey].
2. Introduction 2. Introduction
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prefixes should be damped. The values recommended in Section 6 prefixes should be damped. The values recommended in Section 6
achieve this. Thus, RFD can be enabled, and some churn reduced. achieve this. Thus, RFD can be enabled, and some churn reduced.
The goal is to, with absolutely minimal change, ameliorate the danger The goal is to, with absolutely minimal change, ameliorate the danger
of current RFD implementations and use. It is not a panacea, nor is of current RFD implementations and use. It is not a panacea, nor is
it a deep and thorough approach to flap reduction. it a deep and thorough approach to flap reduction.
3. RFD Parameters 3. RFD Parameters
The following RFD parameters are common to all implementations. Some The following RFD parameters are common to all implementations. Some
may be tuned by the operator, some not. may be tuned by the operator, some not. There is currently no
consensus on a single set of default values.
+-------------------------+----------+-------+---------+ +-------------------------+----------+-------+---------+
| Parameter | Tunable? | Cisco | Juniper | | Parameter | Tunable? | Cisco | Juniper |
+-------------------------+----------+-------+---------+ +-------------------------+----------+-------+---------+
| Withdrawal | No | 1000 | 1000 | | Withdrawal | No | 1000 | 1000 |
| Re-Advertisement | No | 0 | 1000 | | Re-Advertisement | No | 0 | 1000 |
| Attribute Change | No | 500 | 500 | | Attribute Change | No | 500 | 500 |
| Suppress Threshold | Yes | 2000 | 3000 | | Suppress Threshold | Yes | 2000 | 3000 |
| Half-Life (min) | Yes | 15 | 15 | | Half-Life (min) | Yes | 15 | 15 |
| Reuse Threshold | Yes | 750 | 750 | | Reuse Threshold | Yes | 750 | 750 |
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It is important to understand that the parameters shown in Table 1, It is important to understand that the parameters shown in Table 1,
and the implementation's sampling rate, impose an upper bound on the and the implementation's sampling rate, impose an upper bound on the
penalty value, which we can call the 'computed maximum penalty'. penalty value, which we can call the 'computed maximum penalty'.
In addition, BGP implementations have an internal constant which we In addition, BGP implementations have an internal constant which we
will call the 'maximum penalty' which the current computed penalty will call the 'maximum penalty' which the current computed penalty
may not exceed. may not exceed.
6. Recommendations 6. Recommendations
The following changes are recommended: Use of the following values is recommended:
Router Maximum Penalty: The internal constant for the maximum Router Maximum Penalty: The internal constant for the maximum
penalty value MUST be raised to at least 50,000. penalty value MUST be raised to at least 50,000.
Default Configurable Parameters: In order not to break existing Default Configurable Parameters: In order not to break existing
operational configurations, BGP implementations SHOULD NOT change operational configurations, existing BGP implementations
the default values in Table 1. including, the examples in Table 1, SHOULD NOT change their
default values.
Minimum Suppress Threshold: Operators wishing damping which is much Minimum Suppress Threshold: Operators wishing damping which is much
less destructive than current, but still somewhat aggressive less destructive than current, but still somewhat aggressive
SHOULD configure the Suppress Threshold to no less than 6,000. SHOULD configure the Suppress Threshold to no less than 6,000.
Conservative Suppress Threshold: Conservative operators SHOULD Conservative Suppress Threshold: Conservative operators SHOULD
configure the Suppress Threshold to no less than 12,000. configure the Suppress Threshold to no less than 12,000.
Calculate But Do Not Damp: Implementations MAY have a test mode Calculate But Do Not Damp: Implementations MAY have a test mode
where the operator could see the results of a particular where the operator could see the results of a particular
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Keyur Patel Keyur Patel
Cisco Systems Cisco Systems
170 W. Tasman Drive 170 W. Tasman Drive
San Jose, CA 95134 San Jose, CA 95134
US US
Email: keyupate@cisco.com Email: keyupate@cisco.com
Pradosh Mohapatra Pradosh Mohapatra
Cisco Systems Cumulus Systems, Inc.
170 W. Tasman Drive 2672 Bayshore Parkway, Suite 515
San Jose, CA 95134 Mountain View, CA 94043
US US
Email: pmohapat@cisco.com Email: pmohapat@cumulusnetworks.com
Olaf Maennel Olaf Maennel
Loughborough University Loughborough University
Department of Computer Science - N.2.03 Department of Computer Science - N.2.03
Loughborough Loughborough
UK UK
Phone: +44 115 714 0042 Phone: +44 115 714 0042
Email: o@maennel.net Email: o@maennel.net
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