Network Working Group                                         S. Bradner
Internet-Draft                                        Harvard University
Intended status: Informational                                 K. Dubray
Expires: December 14, 2012 February 12, 2013                              Juniper Networks
                                                              J. McQuaid
                                                            Turnip Video
                                                               A. Morton
                                                               AT&T Labs
                                                           June 12,
                                                         August 11, 2012

RFC 2544 Applicability Statement: Use on Production Networks Considered


   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

   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 December 14, 2012. February 12, 2013.

Copyright Notice

   Copyright (c) 2012 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
   ( 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 . . . . . . . . . . . . . . . . . . . . 6 7
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 7
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . . . 7 8
     10.1. Normative References  . . . . . . . . . . . . . . . . . . . 7 8
     10.2. Informative References  . . . . . . . . . . . . . . . . . . 8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 8

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

   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",
   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

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

   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.

   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 through 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

   We note that a range of IPv6 addresses has been assigned to BMWG for
   laboratory test purposes, in [RFC5180]. [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.

   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

   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

   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.

   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

   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

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.

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

   Phone: +1 617 495 3864

   Kevin Dubray
   Juniper Networks


   Jim McQuaid
   Turnip Video
   6 Cobbleridge Court
   Durham, North Carolina  27713

   Phone: +1 919-619-3220

   Al Morton
   AT&T Labs
   200 Laurel Avenue South
   Middletown,, NJ  07748

   Phone: +1 732 420 1571
   Fax:   +1 732 368 1192