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Versions: 00 draft-ietf-ippm-metric-registry

Network Working Group                                         M. Bagnulo
Internet-Draft                                                      UC3M
Intended status: Best Current Practice                         B. Claise
Expires: August 16, 2014                             Cisco Systems, Inc.
                                                              P. Eardley
                                                                      BT
                                                               A. Morton
                                                               AT&T Labs
                                                       February 12, 2014


                    Registry for Performance Metrics
                draft-manyfolks-ippm-metric-registry-00

Abstract

   This document specifies the common aspects of the IANA registry for
   performance metrics, both active and passive categories.  This
   document also gives a set of guidelines for Registered Performance
   Metric requesters and reviewers.

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 August 16, 2014.

Copyright Notice

   Copyright (c) 2014 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



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   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.  Open Issues and Resolutions . . . . . . . . . . . . . . . . .   2
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   5
   4.  Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . .   6
   5.  Design Considerations for the Registry and Registered Metrics   7
     5.1.  Interoperability  . . . . . . . . . . . . . . . . . . . .   7
     5.2.  Criteria for Registered Performance Metrics . . . . . . .   8
     5.3.  Single point of reference for Performance metrics . . . .   8
     5.4.  Side benefits . . . . . . . . . . . . . . . . . . . . . .   9
   6.  Performance Metric Registry: Prior attempt  . . . . . . . . .   9
     6.1.  Why this Attempt Will Succeed?  . . . . . . . . . . . . .  10
   7.  Common Columns of the Performance Metric Registry . . . . . .  10
     7.1.  Performance Metrics Identifier  . . . . . . . . . . . . .  11
     7.2.  Performance Metrics Name  . . . . . . . . . . . . . . . .  11
     7.3.  Performance Metrics Status  . . . . . . . . . . . . . . .  12
     7.4.  Performance Metrics Requester . . . . . . . . . . . . . .  12
     7.5.  Performance Metrics Revision  . . . . . . . . . . . . . .  12
     7.6.  Performance Metrics Revision Date . . . . . . . . . . . .  13
     7.7.  Performance Metrics Description . . . . . . . . . . . . .  13
     7.8.  Reference Specification(s)  . . . . . . . . . . . . . . .  13
   8.  The Life-Cycle of Registered Metrics  . . . . . . . . . . . .  13
     8.1.  The Process for Review by the Performance Metric Experts   13
     8.2.  Revising Registered Performance Metrics . . . . . . . . .  14
     8.3.  Deprecating Registered Performance Metrics  . . . . . . .  16
   9.  Performance Metric Registry and other Registries  . . . . . .  16
   10. Security considerations . . . . . . . . . . . . . . . . . . .  17
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  17
   12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  17
   13. References  . . . . . . . . . . . . . . . . . . . . . . . . .  17
     13.1.  Normative References . . . . . . . . . . . . . . . . . .  17
     13.2.  Informative References . . . . . . . . . . . . . . . . .  18
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  18

1.  Open Issues and Resolutions

   1.   I believe that the Performance Metrics Experts and the
        Performance Metric Directorate will be a different group of
        people.  Reason: every single time a new expert is added, the
        IESG needs to approve her/him.  To be discussed with the Area
        Directors. *** (v7) Has this discussion taken place?  If these




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        are different groups, we don't need to define Performance
        Metrics Directorate.

   2.   We should expand on the different roles and responsibilities of
        the Performance Metrics Experts versus the Performance Metric
        Directorate.  At least, the Performance Metric Directorate one
        should be expanded. --- (v7) If these are different entities,
        our only concern is the role of the "PM Experts".

   3.   Not sure if this is interesting for this document to go in the
        details of the LMAP control protocol versus report protocol (see
        section 'Interoperability'. (the text currently does this in
        several sections, S5 comes to mind - Closed)

   4.   Marcelo, not sure what you mean by 'Single point of reference'.
        (Closed - see S5.3)

   5.   Define 'Measurement Parameter'.  Even if this is active
        monitoring specific term, we need it in this draft.  Done in v3
        Terminology section as "Input Parameter". - Closed in v7 as
        "Parameter".

   6.   Performance Metric Description: part of this document of the
        active/ passive monitoring documents. -- Closed will be Part of
        Active & Passive docs.

   7.   Many aspects of the Naming convention are TBD, and need
        discussion.  For example, we have distinguished RTCP-XR metrics
        as End-Point (neither active nor passive in the traditional
        sense, so not Act_ or Pas_).  Also, the Act_ or Pas_ component
        is not consistent with "camel_case", as Marcelo points out.
        Even though we may not cast all naming conventions in stone at
        the start, it will be helpful to look at several examples of
        passive metric names now.

   8.   RTCP-XR metrics are currently referred to as "end-point", and
        have aspects that similar to active (the measured stream
        characteristics are known a priori and measurement commonly
        takes place at the end-points of the path) and passive (there is
        no additional traffic dedicated to measurement, with the
        exception of the RTCP report packets themselves).  We have one
        example expressing an end-point metric in the active sub-
        registry memo.

   9.   Revised Registry Entries: Keep for history (deprecated) or
        Delete?





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   10.  In section 7 defining the Registry Common Columns, ~all column
        names begin with "Performance Metric".  Al recommends deleting
        this prefix in each sub-section as redundant.

2.  Introduction

   The IETF specifies and uses Performance Metrics of protocols and
   applications transported over its protocols.  Performance metrics are
   such an important part of the operations of IETF protocols that
   [RFC6390] specifies guidelines for their development.

   The definition and use of Performance Metrics in the IETF happens in
   various working groups (WG), most notably:

      The "IP Performance Metrics" (IPPM) WG is the WG primarily
      focusing on Performance Metrics definition at the IETF.

      The "Metric Blocks for use with RTCP's Extended Report Framework"
      (XRBLOCK) WG recently specified many Performance Metrics related
      to "RTP Control Protocol Extended Reports (RTCP XR)" [RFC3611],
      which establishes a framework to allow new information to be
      conveyed in RTCP, supplementing the original report blocks defined
      in "RTP: A Transport Protocol for Real-Time Applications",
      [RFC3550].

      The "Benchmarking Methodology" WG (BMWG) defined many Performance
      Metrics for use in laboratory benchmarking of inter-networking
      technologies.

      The "IP Flow Information eXport" (IPFIX) WG Information elements
      related to Performance Metrics are currently proposed.

      The "Performance Metrics for Other Layers" (PMOL) concluded WG,
      defined some Performance Metrics related to Session Initiation
      Protocol (SIP) voice quality [RFC6035].

   It is expected that more Performance Metrics will be defined in the
   future, not only IP-based metrics, but also metrics which are
   protocol-specific and application-specific.

   However, despite the importance of Performance Metrics, there are two
   related problems for the industry.  First, how to ensure that when
   one party requests another party to measure (or report or in some way
   act on) a particular performance metric, then both parties have
   exactly the same understanding of what performance metric is being
   referred to.  Second, how to discover which Performance Metrics have
   been specified, so as to avoid developing new performance metric that
   is very similar.  The problems can be addressed by creating a



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   registry of performance metrics.  The usual way in which IETF
   organizes namespaces is with Internet Assigned Numbers Authority
   (IANA) registries, and there is currently no Performance Metrics
   Registry maintained by the IANA.

   This document therefore proposes the creation of a Performance
   Metrics Registry.  It also provides best practices on how to define
   new or updated entries in the Performance Metrics Registry.

3.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   [RFC2119].

   The terms Performance Metric and Performance Metrics Directorate are
   defined in [RFC6390], and copied over in this document for the
   readers convenience.

   Registered Performance Metric:  A Registered Performance Metric (or
      Registered Metric) is a quantitative measure of performance (see
      section 6.1 of [RFC2330]) expressed as an entry in the Performance
      Metric Registry, and comprised of a specifically named metric
      which has met all the registry review criteria, is under the
      curation of IETF Performance Metrics Experts, and whose changes
      are controlled by IANA.

   Registry or Performance Metrics Registry:  The IANA registry
      containing Registered Performance Metrics.

   Non-IANA Registry:  A set of metrics that are registered locally (and
      not by IANA).

   Performance Metrics Experts:  The Performance Metrics Experts is a
      group of experts selected by the IESG to validate the Performance
      Metrics before updating the Performance Metrics Registry.  The
      Performance Metrics Experts work closely with IANA.

   Performance Metrics Directorate:  The Performance Metrics Directorate
      is a directorate that provides guidance for Performance Metrics
      development in the IETF.  The Performance Metrics Directorate
      should be composed of experts in the performance community,
      potentially selected from the IP Performance Metrics (IPPM),
      Benchmarking Methodology (BMWG), and Performance Metrics for Other
      Layers (PMOL) WGs.





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   Parameter:  An input factor defined as a variable in the definition
      of a metric.  A numerical or other specified factor forming one of
      a set that defines a metric or sets the conditions of its
      operation.  Most Input Parameters do not change the fundamental
      nature of the metric's definition, but others have substantial
      influence.  All Input Parameters must be known to measure using a
      metric and interpret the results.

   Active Measurement Method:  Methods of Measurement conducted on
      traffic which serves only the purpose of measurement and is
      generated for that reason alone, and whose traffic characteristics
      are known a priori.  An Internet user's host can generate active
      measurement traffic (virtually all typical user-generated traffic
      is not dedicated to active measurement, but it can produce such
      traffic with the necessary application operating).

   Passive Measurement Method:  Methods of Measurement conducted on
      Internet user traffic such that sensitive information is present
      and may be stored in the measurement system, or observations of
      traffic from other sources for monitoring and measurement
      purposes.

   Hybrid Measurement Method:  Methods of Measurement which use a
      combination of Active Measurement and Passive Measurement methods.

4.  Scope

   The intended audience of this document includes those who prepare and
   submit a request for a Registered Performance Metric, and for the
   Performance Metric Experts who review a request.

   This document specifies a Performance Metrics Registry in IANA.  This
   Performance Metric Registry is applicable to Performance Metrics
   issued from Active Measurement, Passive Measurement, or from end-
   point calculation.  This registry is designed to encompass
   performance metrics developed throughout the IETF and especially for
   the following working groups: IPPM, XRBLOCK, IPFIX, BMWG, and
   possibly others.  This document analyzes an prior attempt to set up a
   Performance Metric Registry, and the reasons why this design was
   inadequate [RFC6248].  Finally, this document gives a set of
   guidelines for requesters and expert reviewers of candidate
   Registered Performance Metrics.

   This document serves as the foundation for further work.  It
   specifies the set of columns describing common aspects necessary for
   all entries in the Performance Metrics Registry.





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   Two documents describing sub-registries will be developed separately:
   one for active Registered Metrics and another one for the passive
   Registered Metrics.  Indeed, active and passive performance metrics
   appear to have different characteristics which must be documented in
   their respective sub-registies.  For example, active performance
   methods must specify the packet stream characteristics they generate
   and measure, so it is essential to include the stream specifications
   in the registry entry.  In the case of passive Performance metrics,
   there is a need to specify the sampling distribution in the registry,
   while it would be possible to force the definition of the registry
   field to include both types of distributions in the same registry
   column, we believe it is cleaner and clearer to have separated sub-
   registries with different columns that have a narrow definition.

   It is possible that future metrics may be a hybrid of active and
   passive measurement methods, and it may be possible to register
   hybrid metrics using in one of the two planned sub-registries (active
   or passive), or it may be efficient to define a third sub-registry
   with unique columns.  The current design with sub-registries allows
   for growth, and this is a recognized option for extension.

   This document makes no attempt to populate the registry with initial
   entries.

   Based on [RFC5226] Section 4.3, this document is processed as Best
   Current Practice (BCP) [RFC2026].

5.  Design Considerations for the Registry and Registered Metrics

   In this section, we detail several design considerations that are
   relevant for understanding the motivations and expected use of the
   metric registry.

5.1.  Interoperability

   As any IETF registry, the primary use for a registry is to manage a
   namespace for its use within one or more protocols.  In this
   particular case of the metric registry, there are two types of
   protocols that will use the values defined in the registry for their
   operation:

   o  Control protocol: this type of protocols is used to allow one
      entity to request another entity to perform a measurement using a
      specific metric defined by the registry.  One particular example
      is the LMAP framework [I-D.ietf-lmap-framework].  Using the LMAP
      terminology, the registry is used in the LMAP Control protocol to
      allow a Controller to request a measurement task to one or more
      Measurement Agents.  In order to enable this use case, the entries



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      of the metric registry must be well enough defined to allow a
      Measurement Agent implementation to trigger a specific measurement
      task upon the reception of a control protocol message.  This
      requirements heavily constrains the type of entries that are
      acceptable for the Metric registry.

   o  Report protocol: This type of protocols is used to allow an entity
      to report measurement results to another entity.  By referencing
      to a specific metric registry, it is possible to properly
      characterize the measurement result data being transferred.  Using
      the LMAP terminology, the registry is used in the Report protocol
      to allow a Measurement Agent to report measurement results to a
      Collector.

5.2.  Criteria for Registered Performance Metrics

   It is neither possible nor desirable to populate the registry with
   all combinations of input parameters of all performance metrics.  The
   Registered Performance Metrics should be:

   1.  interpretable by the user.

   2.  implementable by the software designer.

   3.  deployable by network operators, without major impact on the
       networks.

   4.  accurate, for interoperability and deployment across vendors

   In essence, there needs to be evidence that a candidate registry
   entry has significant industry interest, or has seen deployment, and
   there is agreement that the candidate Registered Metric serves its
   intended purpose.

5.3.  Single point of reference for Performance metrics

   A registry for Performance metrics serves as a single point of
   reference for performance metrics defined in different working groups
   in the IETF.  As we mentioned earlier, there are several WGs that
   define performance metrics in the IETF and it is hard to keep track
   of all them.  This results in multiple definitions of similar metrics
   that attempt to measure the same phenomena but in slightly different
   (and incompatible) ways.  Having a registry would allow both the IETF
   community and external people to have a single list of relevant
   performance metrics defined by the IETF (and others, where
   appropriate).  The single list is also an essential aspect of
   communication about metrics, where different entities that request




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   measurements, execute measurements, and report the results can
   benefit from a common understanding of the referenced metric.

5.4.  Side benefits

   There are a couple of side benefits of having such a registry.
   First, the registry could serve as an inventory of useful and used
   metrics, that are normally supported by different implementations of
   measurement agents.  Second, the results of the metrics would be
   comparable even if they are performed by different implementations
   and in different networks, as the metric is properly defined.  BCP
   176 [RFC6576] examines whether the results produced by independent
   implementations are equivalent in the context of evaluating the
   completeness and clarity of metric specifications.  This BCP defines
   the standards track advancement testing for (active) IPPM metrics,
   and the same process will likely suffice to determine whether
   registry entries are sufficiently well specified to result in
   comparable (or equivalent) results.  Registry entries which have
   undergone such testing SHOULD be noted, with a reference to the test
   results.

6.  Performance Metric Registry: Prior attempt

   There was a previous attempt to define a metric registry RFC 4148
   [RFC4148].  However, it was obsoleted by RFC 6248 [RFC6248] because
   it was "found to be insufficiently detailed to uniquely identify IPPM
   metrics... [there was too much] variability possible when
   characterizing a metric exactly" which led to the RFC4148 registry
   having "very few users, if any".

   A couple of interesting additional quotes from RFC 6248 might help
   understand the issues related to that registry.

   1.  "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."

   2.  "The registry structure has been found to be insufficiently
       detailed to uniquely identify IPPM metrics."

   3.  "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."

   The current approach learns from this by tightly defining each entry
   in the registry with only a few parameters open, if any.  The idea is
   that entries in the registry represent different measurement methods



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   which require input parameters to set factors like source and
   destination addresses (which do not change the fundamental nature of
   the measurement).  The downside of this approach is that it could
   result in a large number of entries in the registry.  We believe that
   less is more in this context - it is better to have a reduced set of
   useful metrics rather than a large set of metrics with questionable
   usefulness.  Therefore this document defines that the registry only
   includes metrics that are well defined and that have proven to be
   operationally useful.  In order to guarantee these two
   characteristics we require that a set of experts review the
   allocation request to verify that the metric is well defined and it
   is operationally useful.

6.1.  Why this Attempt Will Succeed?

   The registry defined in this document addresses the main issues
   identified in the previous attempt.  As we mention in the previous
   section, one of the main issues with the previous registry was that
   the metrics contained in the registry were too generic to be useful.
   In this registry, the registry requests are evaluated by an expert
   group that will make sure that the metric is properly defined.  This
   document provides guidelines to assess if a metric is properly
   defined.

   Another key difference between this attempt and the previous one is
   that in this case there is at least one clear user for the registry:
   the LMAP framework and protocol.  Because the LMAP protocol will use
   the registry values in its operation, this actually helps to
   determine if a metric is properly defined.  In particular, since we
   expect that the LMAP control protocol will enable a controller to
   request a measurement agent to perform a measurement using a given
   metric by embedding the metric registry value in the protocol, a
   metric is properly specified if it is defined well-enough so that it
   is possible (and practical) to implement the metric in the
   measurement agent.  This was clearly not the case for the previous
   attempt: defining a metric with an undefined P-Type makes its
   implementation unpractical.

7.  Common Columns of the Performance Metric Registry

   The metric registry is composed of two sub-registries: the registry
   for active performance metrics and the registry for passive
   performance metrics.  The rationale for having two sub-registries (as
   opposed to having a single registry for all metrics) is because the
   set of registry columns must support unambiguous registry entries,
   and there are fundamental differences in the methods to collect
   active and passive metrics and the required input parameters.
   Forcing them into a single, generalized registry would result in a



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   less meaningful structure for some entries in the registry.
   Nevertheless, it is desirable that the two sub-registries share the
   same structure as much as possible.  In particular, both registries
   will share the following columns: the identifier and the name, the
   requester, the revision, the revision date and the description.  All
   these fields are described below.  The design of these two sub-
   registries is work-in-progress.

7.1.  Performance Metrics Identifier

   A numeric identifier for the Registered Performance Metric.  This
   identifier must be unique within the Performance Metric Registry and
   sub-registries.

   The Registered Performance Metric unique identifier is a 16-bit
   integer (range 0 to 65535).  When adding newly Registered Performance
   Metrics to the Performance Metric Registry, IANA should assign the
   lowest available identifier to the next active monitoring Registered
   Performance Metric, and the highest available identifier to the next
   passive monitoring Registered Performance Metric.

7.2.  Performance Metrics Name

   As the name of a Registered Performance Metric is the first thing a
   potential implementor will use when determining whether it is
   suitable for a given application, it is important to be as precise
   and descriptive as possible.  Names of Registered Performance
   Metrics:

   1.  "must be chosen carefully to describe the Registered Performance
       Metric and the context in which it will be used."

   2.  "should be unique within the Performance Metric Registry
       (including sub-registries)."

   3.  "must use capital letters for the first letter of each component
       . All other letters are lowercase, even for acronyms.  Exceptions
       are made for acronyms containing a mixture of lowercase and
       capital letters, such as 'IPv4' and 'IPv6'."

   4.  "must use '_' between each component composing the Registered
       Performance Metric name."

   5.  "must start with prefix Act_ for active measurement Registered
       Performance Metric."






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   6.  "must start with prefix Pass_ for passive monitoring Registered
       Performance Metric."  AL COMMENTS: how about just 3 letters for
       consistency: "Pas_"

   7.  MARCELO: I am uncertain whether we should give more guidance here
       for the naming convention.  In particular, the second component
       could be the highest protocol used in the metric (e.g.  UDP, TCP,
       DNS, SIP, ICMP, IPv4, etc). the third component should be a
       descriptive name (like latency, packet loss or similar). the
       fourth component could be stream distribution. the fifth
       component could be the output type (99mean, 95interval). this is
       of course very active metric oriented, would be good if we could
       figure out what is the minimum common structure for both passive
       and active.  TBD.  AL COMMENTS: Let's see some examples for
       passive monitoring.  It may not make sense to have common name
       components, except for Act_ and Pas_.

   8.  BENOIT proposes (approximately this, Al's wording) : The
       remaining rules for naming are left to the Performance Experts to
       determine as they gather experience, so this is an area of
       planned update by a future RFC.

   An example is "Act_UDP_Latency_Poisson_99mean" for a active
   monitoring UDP latency metric using a Poisson stream of packets and
   producing the 99th percentile mean as output.

   >>>> NEED passive naming examples.

7.3.  Performance Metrics Status

   The status of the specification of this Registered Performance
   Metric.  Allowed values are 'current' and 'deprecated'.  All newly
   defined Information Elements have 'current' status.

7.4.  Performance Metrics Requester

   The requester for the Registered Performance Metric.  The requester
   may be a document, such as RFC, or person.

7.5.  Performance Metrics Revision

   The revision number of a Registered Performance Metric, starting at 0
   for Registered Performance Metrics at time of definition and
   incremented by one for each revision.







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7.6.  Performance Metrics Revision Date

   The date of acceptance or the most recent revision for the Registered
   Performance Metric.

7.7.  Performance Metrics Description

   A Registered Performance Metric Description is a written
   representation of a particular registry entry.  It supplements the
   metric name to help registry users select relevant Registered
   Performance Metrics.

7.8.  Reference Specification(s)

   Registry entries that follow the common columns must provide the
   reference specification(s) on which the Registered Performance Metric
   is based.

8.  The Life-Cycle of Registered Metrics

   Once a Performance Metric or set of Performance Metrics has been
   identified for a given application, candidate registry entry
   specifications in accordance with Section X are submitted to IANA to
   follow the process for review by the Performance Metric Experts, as
   defined below.  This process is also used for other changes to the
   Performance Metric Registry, such as deprecation or revision, as
   described later in this section.

   It is also desirable that the author(s) of a candidate registry entry
   seek review in the relevant IETF working group, or offer the
   opportunity for review on the WG mailing list.

8.1.  The Process for Review by the Performance Metric Experts

   Requests to change Registered Metrics in the Performance Metric
   Registry or a linked sub-registry are submitted to IANA, which
   forwards the request to a designated group of experts (Performance
   Metric Experts) appointed by the IESG; these are the reviewers called
   for by the Expert Review RFC5226 policy defined for the Performance
   Metric Registry.  The Performance Metric Experts review the request
   for such things as compliance with this document, compliance with
   other applicable Performance Metric-related RFCs, and consistency
   with the currently defined set of Registered Performance Metrics.

   Authors are expected to review compliance with the specifications in
   this document to check their submissions before sending them to IANA.





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   The Performance Metric Experts should endeavor to complete referred
   reviews in a timely manner.  If the request is acceptable, the
   Performance Metric Experts signify their approval to IANA, which
   changes the Performance Metric Registry.  If the request is not
   acceptable, the Performance Metric Experts can coordinate with the
   requester to change the request to be compliant.  The Performance
   Metric Experts may also choose in exceptional circumstances to reject
   clearly frivolous or inappropriate change requests outright.

   This process should not in any way be construed as allowing the
   Performance Metric Experts to overrule IETF consensus.  Specifically,
   any Registered Metrics that were added with IETF consensus require
   IETF consensus for revision or deprecation.

   Decisions by the Performance Metric Experts may be appealed as in
   Section 7 of RFC5226.

8.2.  Revising Registered Performance Metrics

   Requests to revise the Performance Metric Registry or a linked sub-
   registry are submitted to IANA, which forwards the request to a
   designated group of experts (Performance Metric Experts) appointed by
   the IESG; these are the reviewers called for by the Expert Review
   [RFC5226] policy defined for the Performance Metric Registry.  The
   Performance Metric Experts review the request for such things as
   compliance with this document, compliance with other applicable
   Performance Metric-related RFCs, and consistency with the currently
   defined set of Registered Performance Metrics.

   A request for Revision is ONLY permissible when the changes maintain
   backward-compatibility with implementations of the prior registry
   entry describing a Registered Metric (entries with lower revision
   numbers, but the same Identifier and Name).

   The purpose of the Status field in the Performance Metric Registry is
   to indicate whether the entry for a Registered Metric is 'current' or
   'deprecated'.

   In addition, no policy is defined for revising IANA Performance
   Metric entries or addressing errors therein.  To be certain, changes
   and deprecations within the Performance Metric Registry are not
   encouraged, and should be avoided to the extent possible.  However,
   in recognition that change is inevitable, the provisions of this
   section address the need for revisions.

   Revisions are initiated by sending a candidate Registered Performance
   Metric definition to IANA, as in Section X, identifying the existing
   registry entry.



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   The primary requirement in the definition of a policy for managing
   changes to existing Registered Performance Metrics is avoidance of
   interoperability problems; Performance Metric Experts must work to
   maintain interoperability above all else.  Changes to Registered
   Performance Metrics already in use may only be done in an inter-
   operable way; necessary changes that cannot be done in a way to allow
   interoperability with unchanged implementations must result in
   deprecation of the earlier metric.

   A change to a Registered Performance Metric is held to be backward-
   compatible only when:

   1.  "it involves the correction of an error that is obviously only
       editorial; or"

   2.  "it corrects an ambiguity in the Registered Performance Metric's
       definition, which itself leads to issues severe enough to prevent
       the Registered Performance Metric's usage as originally defined;
       or"

   3.  "it corrects missing information in the metric definition without
       changing its meaning (e.g., the explicit definition of 'quantity'
       semantics for numeric fields without a Data Type Semantics
       value); or"

   4.  "it harmonizes with an external reference that was itself
       corrected."

   5.  "BENOIT: NOTE THAT THERE ARE MORE RULES IN RFC 7013 SECTION 5 BUT
       THEY WOULD ONLY APPLY TO THE ACTIVE/PASSIVE DRAFTS.  TO BE
       DISCUSSED."

   If a change is deemed permissible by the Performance Metric Experts,
   IANA makes the change in the Performance Metric Registry.  The
   requester of the change is appended to the requester in the registry.

   Each Registered Performance Metric in the Registry has a revision
   number, starting at zero.  Each change to a Registered Performance
   Metric following this process increments the revision number by one.

   COMMENT: Al (and Phil) think we should keep old/revised entries as-
   is, marked as deprecated >>>> Since any revision must be inter-
   operable according to the criteria above, there is no need for the
   Performance Metric Registry to store information about old revisions.

   When a revised Registered Performance Metric is accepted into the
   Performance Metric Registry, the date of acceptance of the most




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   recent revision is placed into the revision Date column of the
   registry for that Registered Performance Metric.

   Where applicable, additions to registry entries in the form of text
   Comments or Remarks should include the date, but such additions may
   not constitute a revision according to this process.

8.3.  Deprecating Registered Performance Metrics

   Changes that are not permissible by the above criteria for Registered
   Metric's revision may only be handled by deprecation.  A Registered
   Performance Metric MAY be deprecated and replaced when:

   1.  "the Registered Performance Metric definition has an error or
       shortcoming that cannot be permissibly changed as in
       Section Revising Registered Performance Metrics; or"

   2.  "the deprecation harmonizes with an external reference that was
       itself deprecated through that reference's accepted deprecation
       method; or"

   A request for deprecation is sent to IANA, which passes it to the
   Performance Metric Expert for review, as in Section 'The Process for
   Review by the Performance Metric Experts'.  When deprecating an
   Performance Metric, the Performance Metric description in the
   Performance Metric Registry must be updated to explain the
   deprecation, as well as to refer to any new Performance Metrics
   created to replace the deprecated Performance Metric.

   The revision number of a Registered Performance Metric is incremented
   upon deprecation, and the revision Date updated, as with any
   revision.

   The use of deprecated Registered Metrics should result in a log entry
   or human-readable warning by the respective application.

   Names and Metric ID of deprecated Registered Metrics must not be
   reused.

9.  Performance Metric Registry and other Registries

   BENOIT: TBD.

   THE BASIC IDEA IS THAT PEOPLE COULD DIRECTLY DEFINE PERF.  METRICS IN
   OTHER EXISTING REGISTRIES, FOR SPECIFIC PROTOCOL/ENCODING.  EXAMPLE:
   IPFIX.  IDEALLY, ALL PERF.  METRICS SHOULD BE DEFINED IN THIS
   REGISTRY AND REFERS TO FROM OTHER REGISTRIES.




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10.  Security considerations

   This draft doesn't introduce any new security considerations for the
   Internet.  However, the definition of Performance Metrics may
   introduce some security concerns, and should be reviewed with
   security in mind.

11.  IANA Considerations

   This document specifies the procedure for Performance Metrics
   Registry setup.  IANA is requested to create a new registry for
   performance metrics called "Registered Performance Metrics".

   This Performance Metrics Registry contains two sub registries once
   for active and another one for passive performance metrics.  These
   sub registries are not defined in this document.  However, these two
   sub registries MUST contain the following columns: the identifier and
   the name, the requester, the revision, the revision date and the
   description, as specified in this document.

   New assignments for Performance Metric Registry will be administered
   by IANA through Expert Review [RFC5226], i.e., review by one of a
   group of experts, the Performance Metric Experts, appointed by the
   IESG upon recommendation of the Transport Area Directors.  The
   experts will initially be drawn from the Working Group Chairs and
   document editors of the Performance Metrics Directorate [performance-
   metrics-directorate].

12.  Acknowledgments

   Thanks to Brian Trammell and Bill Cerveny, IPPM chairs, for leading
   some brainstorming sessions on this topic.

13.  References

13.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2026]  Bradner, S., "The Internet Standards Process -- Revision
              3", BCP 9, RFC 2026, October 1996.

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





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

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

   [RFC6248]  Morton, A., "RFC 4148 and the IP Performance Metrics
              (IPPM) Registry of Metrics Are Obsolete", RFC 6248, April
              2011.

   [RFC6390]  Clark, A. and B. Claise, "Guidelines for Considering New
              Performance Metric Development", BCP 170, RFC 6390,
              October 2011.

   [RFC6576]  Geib, R., Morton, A., Fardid, R., and A. Steinmitz, "IP
              Performance Metrics (IPPM) Standard Advancement Testing",
              BCP 176, RFC 6576, March 2012.

13.2.  Informative References

   [RFC3611]  Friedman, T., Caceres, R., and A. Clark, "RTP Control
              Protocol Extended Reports (RTCP XR)", RFC 3611, November
              2003.

   [RFC3550]  Schulzrinne, H., Casner, S., Frederick, R., and V.
              Jacobson, "RTP: A Transport Protocol for Real-Time
              Applications", STD 64, RFC 3550, July 2003.

   [RFC6035]  Pendleton, A., Clark, A., Johnston, A., and H. Sinnreich,
              "Session Initiation Protocol Event Package for Voice
              Quality Reporting", RFC 6035, November 2010.

   [I-D.ietf-lmap-framework]
              Eardley, P., Morton, A., Bagnulo, M., Burbridge, T.,
              Aitken, P., and A. Akhter, "A framework for large-scale
              measurement platforms (LMAP)", draft-ietf-lmap-
              framework-03 (work in progress), January 2014.

Authors' Addresses











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   Marcelo Bagnulo
   Universidad Carlos III de Madrid
   Av. Universidad 30
   Leganes, Madrid  28911
   SPAIN

   Phone: 34 91 6249500
   Email: marcelo@it.uc3m.es
   URI:   http://www.it.uc3m.es


   Benoit Claise
   Cisco Systems, Inc.
   De Kleetlaan 6a b1
   1831 Diegem
   Belgium

   Email: bclaise@cisco.com


   Philip Eardley
   British Telecom
   Adastral Park, Martlesham Heath
   Ipswich
   ENGLAND

   Email: philip.eardley@bt.com


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

   Email: acmorton@att.com















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