draft-ietf-ippm-framework-compagg-04.txt   draft-ietf-ippm-framework-compagg-05.txt 
Network Working Group A. Morton, Ed. Network Working Group A. Morton, Ed.
Internet-Draft AT&T Labs Internet-Draft AT&T Labs
Intended status: Informational S. Van den Berghe, Ed. Intended status: Informational S. Van den Berghe, Ed.
Expires: January 8, 2008 Ghent University - IBBT Expires: May 8, 2008 Ghent University - IBBT
July 7, 2007 November 5, 2007
Framework for Metric Composition Framework for Metric Composition
draft-ietf-ippm-framework-compagg-04 draft-ietf-ippm-framework-compagg-05
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
skipping to change at page 1, line 35 skipping to change at page 1, line 35
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
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."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on January 8, 2008. This Internet-Draft will expire on May 8, 2008.
Copyright Notice Copyright Notice
Copyright (C) The IETF Trust (2007). Copyright (C) The IETF Trust (2007).
Abstract Abstract
This memo describes a framework for composing and aggregating metrics This memo describes a framework for composing and aggregating metrics
(both in time and in space) defined by RFC 2330 and developed by the (both in time and in space) defined by RFC 2330 and developed by the
IPPM working group. The framework describes the generic composition IPPM working group. The framework describes the generic composition
skipping to change at page 2, line 26 skipping to change at page 2, line 26
1.1.2. Measurement Re-use . . . . . . . . . . . . . . . . . . 4 1.1.2. Measurement Re-use . . . . . . . . . . . . . . . . . . 4
1.1.3. Data Reduction and Consolidation . . . . . . . . . . . 4 1.1.3. Data Reduction and Consolidation . . . . . . . . . . . 4
1.1.4. Implications on Measurement Design and Reporting . . . 5 1.1.4. Implications on Measurement Design and Reporting . . . 5
2. Purpose and Scope . . . . . . . . . . . . . . . . . . . . . . 5 2. Purpose and Scope . . . . . . . . . . . . . . . . . . . . . . 5
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Measurement Point . . . . . . . . . . . . . . . . . . . . 5 3.1. Measurement Point . . . . . . . . . . . . . . . . . . . . 5
3.2. Complete path . . . . . . . . . . . . . . . . . . . . . . 6 3.2. Complete path . . . . . . . . . . . . . . . . . . . . . . 6
3.3. Complete path metric . . . . . . . . . . . . . . . . . . . 6 3.3. Complete path metric . . . . . . . . . . . . . . . . . . . 6
3.4. Composed Metric . . . . . . . . . . . . . . . . . . . . . 6 3.4. Composed Metric . . . . . . . . . . . . . . . . . . . . . 6
3.5. Composition Function . . . . . . . . . . . . . . . . . . . 6 3.5. Composition Function . . . . . . . . . . . . . . . . . . . 6
3.6. Ground Truth . . . . . . . . . . . . . . . . . . . . . . . 6 3.6. Index . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.7. Sub-interval . . . . . . . . . . . . . . . . . . . . . . . 6 3.7. Ground Truth . . . . . . . . . . . . . . . . . . . . . . . 6
3.8. Sub-path . . . . . . . . . . . . . . . . . . . . . . . . . 6 3.8. Sub-interval . . . . . . . . . . . . . . . . . . . . . . . 6
3.9. Sub-path metrics . . . . . . . . . . . . . . . . . . . . . 6 3.9. Sub-path . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.10. Sub-path metrics . . . . . . . . . . . . . . . . . . . . . 7
4. Description of Metric Types . . . . . . . . . . . . . . . . . 7 4. Description of Metric Types . . . . . . . . . . . . . . . . . 7
4.1. Temporal Aggregation Description . . . . . . . . . . . . . 7 4.1. Temporal Aggregation Description . . . . . . . . . . . . . 7
4.2. Spatial Aggregation Description . . . . . . . . . . . . . 7 4.2. Spatial Aggregation Description . . . . . . . . . . . . . 8
4.3. Spatial Composition Description . . . . . . . . . . . . . 8 4.3. Spatial Composition Description . . . . . . . . . . . . . 8
4.4. Help Metrics . . . . . . . . . . . . . . . . . . . . . . . 8 4.4. Help Metrics . . . . . . . . . . . . . . . . . . . . . . . 9
4.5. Higher Order Composition . . . . . . . . . . . . . . . . . 9 4.5. Higher Order Composition . . . . . . . . . . . . . . . . . 9
5. Requirements for Composed Metrics . . . . . . . . . . . . . . 9 5. Requirements for Composed Metrics . . . . . . . . . . . . . . 9
6. Guidelines for Defining Composed Metrics . . . . . . . . . . . 10 6. Guidelines for Defining Composed Metrics . . . . . . . . . . . 10
6.1. Ground Truth: Comparison with other IPPM Metrics . . . . . 10 6.1. Ground Truth: Comparison with other IPPM Metrics . . . . . 10
6.1.1. Ground Truth for Temporal Aggregation . . . . . . . . 12 6.1.1. Ground Truth for Temporal Aggregation . . . . . . . . 12
6.1.2. Ground Truth for Spatial Aggregation . . . . . . . . . 13 6.1.2. Ground Truth for Spatial Aggregation . . . . . . . . . 13
6.2. Deviation from the Ground Truth . . . . . . . . . . . . . 13 6.2. Deviation from the Ground Truth . . . . . . . . . . . . . 13
6.3. Incomplete Information . . . . . . . . . . . . . . . . . . 13 6.3. Incomplete Information . . . . . . . . . . . . . . . . . . 13
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
8. Security Considerations . . . . . . . . . . . . . . . . . . . 14 8. Security Considerations . . . . . . . . . . . . . . . . . . . 14
skipping to change at page 5, line 20 skipping to change at page 5, line 20
sampling plan. Also, certain summary statistics are more conducive sampling plan. Also, certain summary statistics are more conducive
to composition than others, and this figures prominently in the to composition than others, and this figures prominently in the
design of measurements and when reporting the results. design of measurements and when reporting the results.
2. Purpose and Scope 2. Purpose and Scope
The purpose of this memo is provide a common framework for the The purpose of this memo is provide a common framework for the
various classes of metrics based on composition of primary metrics. various classes of metrics based on composition of primary metrics.
The scope is limited to the definitions of metrics that are composed The scope is limited to the definitions of metrics that are composed
from primary metrics using a deterministic function. Key information from primary metrics using a deterministic function. Key information
about each metric, such as its assumptions under which the about each metric, such as the assumptions under which the
relationship holds, and possible sources of error/circumstances where relationship holds and possible sources of error/circumstances where
the composition may fail, are included. the composition may fail, are included.
At this time, the scope of effort is limited to the metrics for At this time, the scope of effort is limited to the metrics for
packet loss, delay, and delay variation. Composition of packet packet loss, delay, and delay variation. Composition of packet
reordering metrics is considered a research topic, and beyond the reordering metrics is considered a research topic at the time this
scope at the time this memo was prepared. memo was prepared, and beyond its scope.
This memo will retain the terminology of the IPPM Framework This memo will retain the terminology of the IPPM Framework
[RFC2330]as much as possible, but will extend the terminology when [RFC2330]as much as possible, but will extend the terminology when
necessary. It is assumed that the reader is familiar with the necessary. It is assumed that the reader is familiar with the
concepts introduced in [RFC2330], as they will not be repeated here. concepts introduced in [RFC2330], as they will not be repeated here.
3. Terminology 3. Terminology
This section defines the terminology applicable to the processes of This section defines the terminology applicable to the processes of
Metric Composition and Aggregation. Metric Composition and Aggregation.
skipping to change at page 6, line 21 skipping to change at page 6, line 21
The complete path metric is the Source to Destination metric that a The complete path metric is the Source to Destination metric that a
composed metric is estimating. A complete path metric represents the composed metric is estimating. A complete path metric represents the
ground-truth for a composed metric. ground-truth for a composed metric.
3.4. Composed Metric 3.4. Composed Metric
A composed metric is an estimate of an actual metric describing the A composed metric is an estimate of an actual metric describing the
performance of a path over some time interval. A composed metric is performance of a path over some time interval. A composed metric is
derived from other metrics by applying a deterministic process or derived from other metrics by applying a deterministic process or
function (e.g., a composition function). function (e.g., a composition function). The process may use metrics
that are identical to the metric being composed, or metrics that are
dissimilar, or some combination of both types.
3.5. Composition Function 3.5. Composition Function
A composition function is a deterministic process applied to A composition function is a deterministic process applied to
individual metrics to derive another metric (such as a Composed individual metrics to derive another metric (such as a Composed
metric). metric).
3.6. Ground Truth 3.6. Index
An Index is a composed metric for which the output value range has
been selected for convenience or clarity, and the behavior of which
is selected to support ease of understanding. The composition
function for an index is often developed after the index range and
index behavior have been determined. Examples include the R factor,
as described in [G.107].
3.7. Ground Truth
As applied here, the notion of ground truth is defined as the actual As applied here, the notion of ground truth is defined as the actual
performance of a network path over some time interval. The ground performance of a network path over some time interval. The ground
truth is metric based on the (unavailable) measurement that a truth is metric based on the (unavailable) measurement that a
composed metric seeks to estimate. composed metric seeks to estimate.
3.7. Sub-interval 3.8. Sub-interval
A Sub-interval is a time interval that is included in another A Sub-interval is a time interval that is included in another
interval. interval.
3.8. Sub-path 3.9. Sub-path
A Sub-path is a portion of the complete path where at least the Sub- A Sub-path is a portion of the complete path where at least the Sub-
path Source and Destination hosts are constituents of the complete path Source and Destination hosts are constituents of the complete
path. We say that this sub-path is "involved" in the complete path. path. We say that this sub-path is "involved" in the complete path.
3.9. Sub-path metrics 3.10. Sub-path metrics
A sub-path path metric is an element of the process to derive a A sub-path path metric is an element of the process to derive a
Composite metric, quantifying some aspect of the performance a Composite metric, quantifying some aspect of the performance a
particular sub-path from its Source to Destination. particular sub-path from its Source to Destination.
4. Description of Metric Types 4. Description of Metric Types
This section defines the various classes of Composition. There are This section defines the various classes of Composition. There are
two classes more accurately described as aggregation over time and two classes more accurately described as aggregation over time and
space, and the third involves concatenation in space. space, and the third involves concatenation in space.
skipping to change at page 9, line 33 skipping to change at page 9, line 49
The definitions for all composed metrics MUST include sections to The definitions for all composed metrics MUST include sections to
treat the following topics. treat the following topics.
The description of each metric will clearly state: The description of each metric will clearly state:
1. the definition (and statistic, where appropriate); 1. the definition (and statistic, where appropriate);
2. the composition or aggregation relationship; 2. the composition or aggregation relationship;
3. the specific conjecture on which the relationship is based; 3. the specific conjecture on which the relationship is based and
assumptions of the statistical model of the process being
measured, if any (see [RFC2330] section 12);
4. a justification of practical utility or usefulness for analysis 4. a justification of practical utility or usefulness for analysis
using the A-frame concepts; using the A-frame concepts;
5. one or more examples of how the conjecture could be incorrect and 5. one or more examples of how the conjecture could be incorrect and
lead to inaccuracy; lead to inaccuracy;
6. the information to be reported. 6. the information to be reported.
Each metric will require a relationship to determine the aggregated For each metric, the applicable circumstances will be defined, in
or composed metric. The relationships may involve conjecture, and terms of whether the composition or aggregation:
[RFC2330] lists four points that the metric definitions should
include:
o the specific conjecture applied to the metric,
o a justification of the practical utility of the composition, in
terms of making accurate measurements of the metric on the path,
o a justification of the usefulness of the aggregation or
composition in terms of making analysis of the path using A-frame
concepts more effective, and
o an analysis of how the conjecture could be incorrect.
For each metric, the applicable circumstances are defined, in terms
of whether the composition or aggregation:
o Requires homogeneity of measurement methodologies, or can allow a o Requires homogeneity of measurement methodologies, or can allow a
degree of flexibility (e.g., active or passive methods produce the degree of flexibility (e.g., active or passive methods produce the
"same" metric). Also, the applicable sending streams will be "same" metric). Also, the applicable sending streams will be
specified, such as Poisson, Periodic, or both. specified, such as Poisson, Periodic, or both.
o Needs information or access that will only be available within an o Needs information or access that will only be available within an
operator's domain, or is applicable to Inter-domain composition. operator's domain, or is applicable to Inter-domain composition.
o Requires precisely synchronized measurement time intervals in all o Requires precisely synchronized measurement time intervals in all
skipping to change at page 14, line 16 skipping to change at page 14, line 16
The security considerations that apply to any active measurement of The security considerations that apply to any active measurement of
live networks are relevant here as well. See [RFC4656]. live networks are relevant here as well. See [RFC4656].
9. Acknowledgements 9. Acknowledgements
The authors would like to thank Maurizio Molina, Andy Van Maele, The authors would like to thank Maurizio Molina, Andy Van Maele,
Andreas Haneman, Igor Velimirovic, Andreas Solberg, Athanassios Andreas Haneman, Igor Velimirovic, Andreas Solberg, Athanassios
Liakopulos, David Schitz, Nicolas Simar and the Geant2 Project. We Liakopulos, David Schitz, Nicolas Simar and the Geant2 Project. We
also acknowledge comments and suggestions from Phil Chimento, Emile also acknowledge comments and suggestions from Phil Chimento, Emile
Stephan, Lei Liang, and Stephen Wolff. Stephan, Lei Liang, Stephen Wolff, and Alan Clark.
10. References 10. References
10.1. Normative References 10.1. Normative References
[I-D.ietf-ippm-multimetrics] [I-D.ietf-ippm-multimetrics]
Stephan, E., "IP Performance Metrics (IPPM) for spatial Stephan, E., "IP Performance Metrics (IPPM) for spatial
and multicast", draft-ietf-ippm-multimetrics-04 (work in and multicast", draft-ietf-ippm-multimetrics-04 (work in
progress), July 2007. progress), July 2007.
skipping to change at page 15, line 5 skipping to change at page 14, line 40
[RFC2330] Paxson, V., Almes, G., Mahdavi, J., and M. Mathis, [RFC2330] Paxson, V., Almes, G., Mahdavi, J., and M. Mathis,
"Framework for IP Performance Metrics", RFC 2330, "Framework for IP Performance Metrics", RFC 2330,
May 1998. May 1998.
[RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. [RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.
Zekauskas, "A One-way Active Measurement Protocol Zekauskas, "A One-way Active Measurement Protocol
(OWAMP)", RFC 4656, September 2006. (OWAMP)", RFC 4656, September 2006.
10.2. Informative References 10.2. Informative References
[G.107] ITU-T Recommendation G.107, ""The E-model, a computational
model for use in transmission planning"", March 2005.
Authors' Addresses Authors' Addresses
Al Morton (editor) Al Morton (editor)
AT&T Labs AT&T Labs
200 Laurel Avenue South 200 Laurel Avenue South
Middletown,, NJ 07748 Middletown,, NJ 07748
USA USA
Phone: +1 732 420 1571 Phone: +1 732 420 1571
Fax: +1 732 368 1192 Fax: +1 732 368 1192
 End of changes. 17 change blocks. 
38 lines changed or deleted 40 lines changed or added

This html diff was produced by rfcdiff 1.34. The latest version is available from http://tools.ietf.org/tools/rfcdiff/