draft-ietf-idr-rfd-usable-02.txt   draft-ietf-idr-rfd-usable-03.txt 
Network Working Group C.P. Pelsser Network Working Group C. Pelsser
Internet-Draft R.B. Bush Internet-Draft R. Bush
Intended status: Standards Track Internet Initiative Japan Intended status: Standards Track Internet Initiative Japan
Expires: September 12, 2013 K.P. Patel Expires: February 23, 2014 K. Patel
P.M. Mohapatra P. Mohapatra
Cisco Systems Cisco Systems
O.M. Maennel O. Maennel
Loughborough University Loughborough University
March 11, 2013 August 22, 2013
Making Route Flap Damping Usable Making Route Flap Damping Usable
draft-ietf-idr-rfd-usable-02 draft-ietf-idr-rfd-usable-03
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
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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 September 12, 2013. This Internet-Draft will expire on February 23, 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
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publication of this document. Please review these documents publication of this document. Please review these documents
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4. Suppress Threshold Versus Churn 4. Suppress Threshold Versus Churn
By turning RFD back on with the values recommended in Section 6 churn By turning RFD back on with the values recommended in Section 6 churn
is reduced. Moreover, with these values, prefixes going through is reduced. Moreover, with these values, prefixes going through
normal convergence are generally not damped. normal convergence are generally not damped.
[pelsser2011] estimates that, with a suppress threshold of 6,000, the [pelsser2011] estimates that, with a suppress threshold of 6,000, the
BGP update rate is reduced by 19% compared to a situation without RFD BGP update rate is reduced by 19% compared to a situation without RFD
enabled. With this 6,000 suppress threshold, 90% fewer prefixes are enabled. With this 6,000 suppress threshold, 90% fewer prefixes are
damped compared to use of a 2,000 threshold. I.e. far fewer well- damped compared to use of a 2,000 threshold. I.e. far fewer well-
behaved prefixes are damped. behaved prefixes are damped.
Setting the suppress threshold to 12,000 leads to very few damped Setting the suppress threshold to 12,000 leads to very few damped
prefixes (1.7% of the prefixes damped with a threshold of 2,000, in prefixes (1.7% of the prefixes damped with a threshold of 2,000, in
the experiments in [pelsser2011] yielding an average hourly update the experiments in [pelsser2011] yielding an average hourly update
reduction of 11% compared to not using RFD. reduction of 11% compared to not using RFD.
+-----------------+-----------------+-------------+-----------------+ +-----------------+-----------------+-------------+-----------------+
| Suppress | Damped | % of Table | Update Rate | | Suppress | Damped | % of Table | Update Rate |
| Threshold | Instances | Damped | (one hour bins) | | Threshold | Instances | Damped | (one hour bins) |
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| 6,000 | 4352 | 1.32% | 81.03% | | 6,000 | 4352 | 1.32% | 81.03% |
| 8,000 | 2104 | 0.64% | 84.85% | | 8,000 | 2104 | 0.64% | 84.85% |
| 10,000 | 1286 | 0.39% | 87.12% | | 10,000 | 1286 | 0.39% | 87.12% |
| 12,000 | 720 | 0.22% | 88.74% | | 12,000 | 720 | 0.22% | 88.74% |
| 14,000 | 504 | 0.15% | 89.97% | | 14,000 | 504 | 0.15% | 89.97% |
| 16,000 | 353 | 0.11% | 91.01% | | 16,000 | 353 | 0.11% | 91.01% |
| 18,000 | 311 | 0.09% | 91.88% | | 18,000 | 311 | 0.09% | 91.88% |
| 20,000 | 261 | 0.08% | 92.69% | | 20,000 | 261 | 0.08% | 92.69% |
+-----------------+-----------------+-------------+-----------------+ +-----------------+-----------------+-------------+-----------------+
Damped Prefixes vs. Churn, from [pelsser2011]. Note overly- Damped Prefixes vs. Churn, from [pelsser2011]. Note overly-
aggressive current default Suppress Threshold aggressive current default Suppress Threshold
Table 2 Table 2
5. Maximum Penalty 5. Maximum Penalty
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'.
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[RFC2439] Villamizar, C., Chandra, R., and R. Govindan, "BGP Route [RFC2439] Villamizar, C., Chandra, R., and R. Govindan, "BGP Route
Flap Damping", RFC 2439, November 1998. Flap Damping", RFC 2439, November 1998.
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
Protocol 4 (BGP-4)", RFC 4271, January 2006. Protocol 4 (BGP-4)", RFC 4271, January 2006.
[mao2002] Mao, Z. M., Govidan, R., Varghese, G., Katz, R., "Route [mao2002] Mao, Z. M., Govidan, R., Varghese, G., Katz, R., "Route
Flap Damping Excacerbates Internet Routing Convergence", Flap Damping Excacerbates Internet Routing Convergence",
In Proceedings of SIGCOMM , August 2002, <http:// In Proceedings of SIGCOMM , August 2002, <http://
www.acm.org/sigcomm/sigcomm2002/papers/ conferences.sigcomm.org/sigcomm/2002/papers/
routedampening.pdf>. routedampening.pdf>.
[pelsser2011] [pelsser2011]
Pelsser, C., Maennel, O., Mohapatra, P., Bush, R., Patel, Pelsser, C., Maennel, O., Mohapatra, P., Bush, R., Patel,
K., "Route Flap Damping Made Usable", Passive and Active K., "Route Flap Damping Made Usable", Passive and Active
Measurement (PAM), March 2011, Measurement (PAM), March 2011,
<http://pam2011.gatech.edu/papers/pam2011--Pelsser.pdf>. <http://pam2011.gatech.edu/papers/pam2011--Pelsser.pdf>.
[ripe378] Panigl, P. Smith, P., "RIPE Routing Working Group [ripe378] Panigl, P. Smith, P., "RIPE Routing Working Group
Recommendations On Route-flap Damping", 2006, Recommendations On Route-flap Damping", 2006,
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