RFC 6248 INFORMATIONAL MEASUREMENT · IANA · INFRASTRUCTURE

IPPM registry obsolete: RFC 4148 and the IP Performance Metrics (IPPM) Registry of Metrics Are Obsolete

Why the IP Performance Metrics registry was withdrawn from use.

On rfc-editor.org ↗
PUBLISHED
April 2011
AUTHORS
A. Morton
STREAM
IETF
BUILDS ON
RFC 4148 — IPPM metrics registry, RFC 4737 — Reordering metrics, RFC 5560 — Packet duplication, RFC 5644 — IPPM spatial/multicast, RFC 6049 — Spatial Composition of Metrics
REGISTRY NAME
IANA IP Performance Metrics (IPPM) Metrics Registry
ORIGINAL RFC
RFC 4148
SYNTAX ERROR DURATION
Eight months
DOI
10.17487/RFC6248

RFC text

Contents
Original text · RFC Editor View on rfc-editor.org ↗
Internet Engineering Task Force (IETF)                         A. Morton
Request for Comments: 6248                                     AT&T Labs
Obsoletes: 4148                                               April 2011
Updates: 4737, 5560, 5644, 6049
Category: Informational
ISSN: 2070-1721


   RFC 4148 and the IP Performance Metrics (IPPM) Registry of Metrics
                              Are Obsolete

Abstract

   This memo reclassifies RFC 4148, "IP Performance Metrics (IPPM)
   Metrics Registry", as Obsolete, and withdraws the IANA IPPM Metrics
   Registry itself from use because it is obsolete.  The current
   registry structure has been found to be insufficiently detailed to
   uniquely identify IPPM metrics.  Despite apparent efforts to find
   current or even future users, no one responded to the call for
   interest in the RFC 4148 registry during the second half of 2010.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   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).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see 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/rfc6248.

Copyright Notice

   Copyright (c) 2011 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
   2. Action to Reclassify RFC 4148 and the Corresponding IANA
      Registry as Obsolete ............................................3
   3. Security Considerations .........................................4
   4. IANA Considerations .............................................4
   5. Acknowledgements ................................................4
   6. References ......................................................5
      6.1. Normative References .......................................5
      6.2. Informative References .....................................5

1.  Introduction

   The IP Performance Metrics (IPPM) framework [RFC2330] describes
   several ways to record options and metric parameter settings, in
   order to account for sources of measurement variability.  For
   example, Section 13 of [RFC2330] describes the notion of "Type P" so
   that metrics can be specified in general, but the specifics (such as
   payload length in octets and protocol type) can replace P to
   disambiguate the results.

   When the IPPM Metrics Registry [RFC4148] was designed, the
   variability of the "Type P" notion, and the variability possible with
   the many metric parameters (see Section 4.2 of [RFC2679]), were not
   fully appreciated.  Further, some of the early metric definitions
   only indicate Poisson streams [RFC2330] (see the metrics in
   [RFC2679], [RFC2680], and [RFC3393]), but later work standardized the
   methods for Periodic Stream measurements [RFC3432], adding to the
   variability possible when characterizing a metric exactly.

   It is not believed to be feasible or even useful to register every
   possible combination of Type P, metric parameters, and Stream
   parameters using the current structure of the IPPM Metrics Registry.

   The IPPM Metrics Registry is believed to have very few users, if any.
   Evidence of this was provided by the fact that one registry entry was
   syntactically incorrect for months after [RFC5644] was published.
   The text ":=" was used for the metrics in that document instead of
   "::=".  It took eight months before someone offered that a parser
   found the error.  Even the original registry author agrees that the
   current registry is not efficient, and has submitted a proposal to
   effectively create a new registry.

   Despite apparent efforts to find current or even future users, no one
   responded to the call for interest in the RFC 4148 registry during
   the second half of 2010.  Therefore, the IETF now declares the
   registry Obsolete without any further reservations.

   When a registry is designated Obsolete, it simply prevents the IANA
   from registering new objects, in this case new metrics.  So, even if
   a registry user was eventually found, they could continue to use the
   current registry, and its contents will continue to be available.

   The most recently published memo that added metrics to the registry
   is [RFC6049].  This memo updates all previous memos that registered
   new metrics, including [RFC4737] and [RFC5560], so that the
   registry's Obsolete status will be evident.

2.  Action to Reclassify RFC 4148 and the Corresponding IANA Registry as
    Obsolete

   Due to the ambiguities between the current metrics registrations and
   the metrics used, and the apparent minimal adoption of the registry
   in practice, it is required that:

   o  the IETF reclassify [RFC4148] as Obsolete.

   o  the IANA withdraw the current IPPM Metrics Registry from further
      updates and note that it too is Obsolete.

   It is assumed that parties who wish to establish a replacement
   registry function will work to specify such a registry.

3.  Security Considerations

   This memo and its recommendations have no known impact on the
   security of the Internet (especially if there is a zombie apocalypse
   on the day it is published; humans will have many more security
   issues to worry about stemming from the rise of the un-dead).

4.  IANA Considerations

   Metrics defined in the IETF have been typically registered in the
   IANA IPPM Metrics Registry as described in the initial version of the
   registry [RFC4148].  However, areas for improvement of this registry
   have been identified, and the registry structure has to be revisited
   when there is working group consensus to do so.

   The current consensus is to designate the IPPM Metrics Registry,
   originally described in [RFC4148], as Obsolete.

   The DESCRIPTION of the registry MIB has been modified as follows, and
   the first two sentences should be included on any IANA-maintained web
   page describing this registry or its contents:

   DESCRIPTION

      "With the approval and publication of RFC 6248, this module is
      designated Obsolete.

      The registry will no longer be updated, and the current contents
      will be maintained as-is on the day that RFC 6248 was published.

      The original Description text follows below:

      This module defines a registry for IP Performance Metrics.

      ... "

5.  Acknowledgements

   Henk Uijterwaal suggested additional rationale for the recommendation
   in this memo.

6.  References

6.1.  Normative References

   [RFC4148]  Stephan, E., "IP Performance Metrics (IPPM) Metrics
              Registry", BCP 108, RFC 4148, August 2005.

6.2.  Informative References

   [RFC2330]  Paxson, V., Almes, G., Mahdavi, J., and M. Mathis,
              "Framework for IP Performance Metrics", RFC 2330,
              May 1998.

   [RFC2679]  Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way
              Delay Metric for IPPM", RFC 2679, September 1999.

   [RFC2680]  Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way
              Packet Loss Metric for IPPM", RFC 2680, September 1999.

   [RFC3393]  Demichelis, C. and P. Chimento, "IP Packet Delay Variation
              Metric for IP Performance Metrics (IPPM)", RFC 3393,
              November 2002.

   [RFC3432]  Raisanen, V., Grotefeld, G., and A. Morton, "Network
              performance measurement with periodic streams", RFC 3432,
              November 2002.

   [RFC4737]  Morton, A., Ciavattone, L., Ramachandran, G., Shalunov,
              S., and J. Perser, "Packet Reordering Metrics", RFC 4737,
              November 2006.

   [RFC5560]  Uijterwaal, H., "A One-Way Packet Duplication Metric",
              RFC 5560, May 2009.

   [RFC5644]  Stephan, E., Liang, L., and A. Morton, "IP Performance
              Metrics (IPPM): Spatial and Multicast", RFC 5644,
              October 2009.

   [RFC6049]  Morton, A. and E. Stephan, "Spatial Composition of
              Metrics", RFC 6049, January 2011.

Author's Address

   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/

AI ELI5

On this page
PROBLEMThe IANA IP Performance Metrics (IPPM) Registry was designed to catalog network measurement metrics, but it turned out to be too vague to uniquely identify metrics, and nobody used it.
MECHANISMThis RFC formally reclassifies RFC 4148 as Obsolete and tells IANA to withdraw the registry from further updates. The registry contents remain available for reference, but no new entries can be added.
STATUSThe IPPM Metrics Registry is officially deprecated. Future work on metrics will need a new registry with better structure.

§1The Problem with the Registry

The IPPM framework (RFC 2330) describes how to measure network performance in general terms. It uses the concept of "Type P" to represent parameters like packet payload length and protocol type, so metrics can be specified broadly but with the ability to fill in specifics.

When the IPPM Metrics Registry (RFC 4148) was designed, the variability in Type P and the many metric parameters were not fully appreciated. Early metrics only documented Poisson streams, but later work standardized Periodic Stream measurements, adding more variability. It became infeasible to register every possible combination of these parameters in a simple registry structure.

Network metrics have many parameters that can change: what kind of traffic, how often it's sent, what size packets. The registry couldn't handle all the combinations.

§2Evidence of Non-use

The IPPM Metrics Registry is believed to have very few users, if any. Strong evidence came when RFC 5644 added entries to the registry using incorrect syntax: ":=" instead of "::=" in the formal notation. This error went unnoticed for eight months before someone's parser found it. If anyone had been actively using the registry, this syntax error would have been caught much sooner.

Even the original registry author agreed that the current structure was not efficient and submitted a proposal to create a new registry with better design. Despite efforts to solicit feedback about continued interest in RFC 4148 during the second half of 2010, no one responded.

A syntax error sat in the registry for months before anyone noticed. If anyone was using it, they would have found the mistake.

§3Declaring Obsolescence

RFC 6248 formally takes two actions:

First, it reclassifies RFC 4148 as Obsolete. Second, it tells IANA to withdraw the IPPM Metrics Registry from further updates and mark it as Obsolete. When a registry is marked Obsolete, IANA stops accepting new registrations, preventing the addition of new metrics.

This does not erase the registry's contents. Existing entries remain available for reference, and if a user were found in the future, they could continue using the current registry. However, new work on metrics will need to establish a replacement registry with a better structure.

The official action is simple: stop accepting new entries to the registry, and mark the whole registry as obsolete. But the old data stays there for reference.

Timeline of the IPPM registry
  1. 2005RFC 4148 creates IPPM Metrics RegistryRFC 4148
  2. 2009RFC 5644 adds entries with syntax error
  3. 2010Effort to find registry users; no response
  4. 2011RFC 6248 marks registry ObsoleteRFC 6248

§4Implications and Next Steps

This RFC also updates four previous RFCs (4737, 5560, 5644, and 6049) that had registered metrics in the now-obsolete registry. By updating these RFCs, the Obsolete status of the registry becomes evident in any documentation that references these metrics.

The memo assumes that parties wishing to establish a replacement registry function will work to specify one with better structure. The lesson is that registries need to account for parameter variability from the start, and that registry adoption should be monitored to ensure registries are actually being used.

The documents that used the registry are updated to note it's obsolete. Future work will need a better registry with more flexible structure.

§5References