RFC 2544 Applicability Statement: Use on Production Networks Considered Harmful
draft-ietf-bmwg-2544-as-05
The information below is for an old version of the document.
| Document | Type | Active Internet-Draft (bmwg WG) | |
|---|---|---|---|
| Authors | Scott O. Bradner , Kevin Dubray , Jim McQuaid , Al Morton | ||
| Last updated | 2012-08-30 (Latest revision 2012-08-11) | ||
| Replaces | draft-chairs-bmwg-2544-as | ||
| Stream | Internet Engineering Task Force (IETF) | ||
| Formats | plain text xml htmlized pdfized bibtex | ||
| Reviews |
GENART Last Call review
Ready
|
||
| Stream | WG state | WG Document | |
| Document shepherd | Bill Cerveny | ||
| IESG | IESG state | IESG Evaluation::Revised I-D Needed | |
| Consensus boilerplate | Unknown | ||
| Telechat date |
(None)
Needs a YES. |
||
| Responsible AD | Ron Bonica | ||
| IESG note | Document Shepherd: Bill Cerveny <wcerveny@wjcerveny.com> | ||
| Send notices to | bmwg-chairs@tools.ietf.org, draft-ietf-bmwg-2544-as@tools.ietf.org, wcerveny@wjcerveny.com |
draft-ietf-bmwg-2544-as-05
Network Working Group S. Bradner
Internet-Draft Harvard University
Intended status: Informational K. Dubray
Expires: February 12, 2013 Juniper Networks
J. McQuaid
Turnip Video
A. Morton
AT&T Labs
August 11, 2012
RFC 2544 Applicability Statement: Use on Production Networks Considered
Harmful
draft-ietf-bmwg-2544-as-05
Abstract
Benchmarking Methodology Working Group (BMWG) has been developing key
performance metrics and laboratory test methods since 1990, and
continues this work at present. Recent application of the methods
beyond their intended scope is cause for concern. The methods
described in RFC 2544, where overload is a possible outcome, would no
doubt be harmful to user traffic performance on a production network.
This memo clarifies the scope of RFC 2544 and other benchmarking work
for the IETF community.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 12, 2013.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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 . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . . 3
2. Scope and Goals . . . . . . . . . . . . . . . . . . . . . . . . 4
3. The Concept of an Isolated Test Environment . . . . . . . . . . 4
4. Why RFC 2544 Methods are intended for ITE . . . . . . . . . . . 4
4.1. Experimental Control and Accuracy . . . . . . . . . . . . . 4
4.2. Containing Damage . . . . . . . . . . . . . . . . . . . . . 5
5. Advisory on RFC 2544 Methods in Production Networks . . . . . . 5
6. What to do without RFC 2544? . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
10.1. Normative References . . . . . . . . . . . . . . . . . . . 8
10.2. Informative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
This memo clarifies the scope of RFC 2544 [RFC2544], which discusses
and defines several tests that may be used to characterize the
performance of a network interconnecting device, and other
benchmarking work for the IETF community.
Benchmarking Methodologies (beginning with [RFC2544]) have always
relied on test conditions that can only be produced and replicated
reliably in the laboratory. Thus it was unfortunate to find that
this foundation methodology was being cited in several unintended
specifications and products performing applications such as:
1. Validation of telecommunication service configuration, such as
the Committed Information Rate (CIR).
2. Validation of performance metrics in a telecommunication Service
Level Agreement (SLA), such as frame loss and latency.
3. Telecommunication service activation testing, where traffic that
shares network resources with the test might be adversely
affected.
Above, we distinguish "telecommunication service" (where a network
service provider contracts with a customer to transfer information
between specified interfaces at different geographic locations) from
the generic term "service". Below, we use the adjective "production"
to refer to networks carrying live user traffic. [RFC2544] used the
term "real-world" to refer to production networks and to
differentiate them from test networks.
Although RFC 2544 is held up as the standard reference for such
testing, we believe that the actual methods used vary from RFC 2544
in significant ways. Since the only citation is to RFC 2544, the
modifications are opaque to the standards community and to users in
general (an undesirable situation). There is risk of harm to user
traffic from applying the test traffic and methods described in
[RFC2544] on a production network, because overload in shared
resources is a possible outcome.
To directly address this situation, the past and present Chairs of
the IETF Benchmarking Methodology Working Group (BMWG) have prepared
this Applicability Statement for RFC 2544.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
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document are to be interpreted as described in RFC 2119 [RFC2119].
2. Scope and Goals
This memo clarifies the scope of [RFC2544], with the goal to provide
guidance to the community on its applicability, which is limited to
laboratory testing.
3. The Concept of an Isolated Test Environment
An Isolated Test Environment (ITE) used with [RFC2544] methods (as
illustrated in Figures 1 through 3 of [RFC2544]) has the ability to:
o contain the test streams to paths within the desired set-up
o prevent non-test traffic from traversing the test set-up
These features allow unfettered experimentation, while at the same
time protecting lab equipment management/control LANs and other
production networks from the unwanted effects of the test traffic.
4. Why RFC 2544 Methods are intended for ITE
The following sections discuss some of the reasons why RFC 2544
[RFC2544] methods were intended only for isolated laboratory use, and
the difficulties of applying these methods outside the lab
environment.
4.1. Experimental Control and Accuracy
All of the tests described in RFC 2544 require that the tester and
device under test are the only devices on the networks that are
transmitting data. The presence of other unwanted traffic on the
network would mean that the specified test conditions have not been
achieved.
If any unwanted traffic appears and the amount varies over time, the
repeatability of any test result will likely depend to some degree on
the unwanted traffic.
The presence of unwanted or unknown traffic makes accurate,
repeatable, and consistent measurements of the performance of the
device under test very unlikely, since the complete details of test
conditions will not be reported.
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For example, the RFC 2544 Throughput Test attempts to characterize a
maximum reliable load, thus there will be testing above the maximum
that causes packet/frame loss. Any other sources of traffic on the
network will cause packet loss to occur at a tester data rate lower
than the rate that would be achieved without the extra traffic.
4.2. Containing Damage
RFC 2544 methods, specifically to determine Throughput as defined in
[RFC1242] and other benchmarks, may overload the resources of the
device under test, and may cause failure modes in the device under
test. Since failures can become the root cause of more wide-spread
failure, it is clearly desirable to contain all test traffic within
the ITE.
In addition, such testing can have a negative effect on any traffic
that shares resources with the test stream(s) since, in most cases,
the traffic load will be close to the capacity of the network links.
Appendix C.2.2 of [RFC2544] (as adjusted by errata) gives the private
IPv4 address range for testing:
"...The network addresses 198.18.0.0 through 198.19.255.255 have been
assigned to the BMWG by the IANA for this purpose. This assignment
was made to minimize the chance of conflict in case a testing device
were to be accidentally connected to part of the Internet. The
specific use of the addresses is detailed below."
In other words, devices operating on the Internet may be configured
to discard any traffic they observe in this address range, as it is
intended for laboratory ITE use only. Thus, testers using the
assigned testing address ranges MUST NOT be connected to the
Internet.
We note that a range of IPv6 addresses has been assigned to BMWG for
laboratory test purposes, in [RFC5180] (as amended by errata). Also,
the strong statements in the Security Considerations Section of this
memo make the scope even more clear; this is now a standard fixture
of all BMWG memos.
5. Advisory on RFC 2544 Methods in Production Networks
The tests in [RFC2544] were designed to measure the performance of
network devices, not of networks, and certainly not production
networks carrying user traffic on shared resources. There will be
unanticipated difficulties when applying these methods outside the
lab environment.
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One such difficulty stems from reliance on frame loss as an indicator
of resource exhaust in RFC 2544 methods. In practice, link-layer and
physical-layer errors prevent production networks from operating
loss-free. The RFC 2544 methods will not correctly assess Throughput
when loss from uncontrolled sources is present. Frame loss occurring
at the SLA levels of some networks could affect every iteration of
Throughput testing (when each step includes sufficient packets to
experience facility-related loss). Flawed results waste the time and
resources of the testing service user, and of the service provider
when called to dispute the measurement. These are additional
examples of harm that compliance with this advisory should help to
avoid.
Operating test equipment on production networks according to the
methods described in [RFC2544], where overload is a possible outcome,
would no doubt be harmful to user traffic performance. These tests
MUST NOT be used on production networks and as discussed above, the
tests will never produce a reliable or accurate benchmarking result
on a production network.
[RFC2544] methods have never been validated on a network path, even
when that path is not part of a production network and carrying no
other traffic. It is unknown whether the tests can be used to
measure valid and reliable performance of a multi-device, multi-
network path. It is possible that some of the tests may prove valid
in some path scenarios, but that work has not been done or has not
been shared with the IETF community. Thus, such testing is contra-
indicated by the BMWG.
6. What to do without RFC 2544?
The IETF has addressed the problem of production network performance
measurement by chartering a different working group: IP Performance
Metrics (IPPM). This working group has developed a set of standard
metrics to assess the quality, performance, and reliability of
Internet packet transfer services. These metrics can be measured by
network operators, end users, or independent testing groups. We note
that some IPPM metrics differ from RFC 2544 metrics with similar
names, and there is likely to be confusion if the details are
ignored.
IPPM has not yet standardized methods for raw capacity measurement of
Internet paths. Such testing needs to adequately consider the strong
possibility for degradation to any other traffic that may be present
due to congestion. There are no specific methods proposed for
activation of a packet transfer service in IPPM.
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Other standards may help to fill gaps in telecommunication service
testing. For example, the IETF has many standards intended to assist
with network operation, administration and maintenance (OAM), and
ITU-T Study Group 12 has a recommendation on service activation test
methodology [Y.1564].
The world will not spin off axis while waiting for appropriate and
standardized methods to emerge from the consensus process.
7. Security Considerations
This Applicability Statement intends to help preserve the security of
the Internet by clarifying that the scope of [RFC2544] and other BMWG
memos are all limited to testing in a laboratory ITE, thus avoiding
accidental Denial of Service attacks or congestion due to high
traffic volume test streams.
All Benchmarking activities are limited to technology
characterization using controlled stimuli in a laboratory
environment, with dedicated address space and the other constraints
[RFC2544].
The benchmarking network topology will be an independent test setup
and MUST NOT be connected to devices that may forward the test
traffic into a production network, or misroute traffic to the test
management network.
Further, benchmarking is performed on a "black-box" basis, relying
solely on measurements observable external to the device under test/
system under test (DUT/SUT).
Special capabilities SHOULD NOT exist in the DUT/SUT specifically for
benchmarking purposes. Any implications for network security arising
from the DUT/SUT SHOULD be identical in the lab and in production
networks.
8. IANA Considerations
This memo makes no requests of IANA.
9. Acknowledgements
Thanks to Matt Zekauskas, Bill Cerveny, Barry Constantine, Curtis
Villamizar, and David Newman for reading and suggesting improvements
to this memo.
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10. References
10.1. Normative References
[RFC1242] Bradner, S., "Benchmarking terminology for network
interconnection devices", RFC 1242, July 1991.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2544] Bradner, S. and J. McQuaid, "Benchmarking Methodology for
Network Interconnect Devices", RFC 2544, March 1999.
[RFC5180] Popoviciu, C., Hamza, A., Van de Velde, G., and D.
Dugatkin, "IPv6 Benchmarking Methodology for Network
Interconnect Devices", RFC 5180, May 2008.
10.2. Informative References
[Y.1564] ITU-T Recommendation Y.1564, "Ethernet Service Activation
Test Methodology", March 2011.
Authors' Addresses
Scott Bradner
Harvard University
29 Oxford St.
Cambridge, MA 02138
USA
Phone: +1 617 495 3864
Fax:
Email: sob@harvard.edu
URI: http://www.sobco.com
Kevin Dubray
Juniper Networks
Phone:
Fax:
Email: kdubray@juniper.net
URI:
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Jim McQuaid
Turnip Video
6 Cobbleridge Court
Durham, North Carolina 27713
USA
Phone: +1 919-619-3220
Fax:
Email: jim@turnipvideo.com
URI: www.turnipvideo.com
Al Morton
AT&T Labs
200 Laurel Avenue South
Middletown,, NJ 07748
USA
Phone: +1 732 420 1571
Fax: +1 732 368 1192
Email: acmorton@att.com
URI: http://home.comcast.net/~acmacm/
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