 1/draftietfippmspatialcomposition00.txt 20060629 05:12:51.000000000 +0200
+++ 2/draftietfippmspatialcomposition01.txt 20060629 05:12:51.000000000 +0200
@@ 1,19 +1,19 @@
Network Working Group A. Morton
InternetDraft AT&T Labs
Expires: August 30, 2006 E. Stephan
+Expires: December 26, 2006 E. Stephan
France Telecom Division R&D
 February 26, 2006
+ June 24, 2006
Spatial Composition of Metrics
 draftietfippmspatialcomposition00
+ draftietfippmspatialcomposition01
Status of this Memo
By submitting this InternetDraft, each author represents that any
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
aware will be disclosed, in accordance with Section 6 of BCP 79.
InternetDrafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
@@ 24,21 +24,21 @@
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use InternetDrafts as reference
material or to cite them other than as "work in progress."
The list of current InternetDrafts can be accessed at
http://www.ietf.org/ietf/1idabstracts.txt.
The list of InternetDraft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
 This InternetDraft will expire on August 30, 2006.
+ This InternetDraft will expire on December 26, 2006.
Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
This memo utilizes IPPM metrics that are applicable to both complete
paths and subpaths, and defines relationships to compose a complete
path metric from the subpath metrics with some accuracy w.r.t. the
@@ 58,87 +58,86 @@
Table of Contents
1. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Scope, Application, and Terminology . . . . . . . . . . . . . 5
3.1. Scope of work . . . . . . . . . . . . . . . . . . . . . . 5
3.2. Application . . . . . . . . . . . . . . . . . . . . . . . 6
3.3. Terminology . . . . . . . . . . . . . . . . . . . . . . . 6
 4. Oneway Delay Composition Metrics and Statistics . . . . . . . 7
+ 4. Oneway Delay Composed Metrics and Statistics . . . . . . . . 7
4.1. Name:
TypePFiniteOnewayDelayPoisson/PeriodicStream . . . 7
4.1.1. Metric Parameters: . . . . . . . . . . . . . . . . . . 7
4.1.2. Definition and Metric Units . . . . . . . . . . . . . 8
4.1.3. Discussion and other details . . . . . . . . . . . . . 8
 4.1.4. Mean Statistic . . . . . . . . . . . . . . . . . . . . 8
 4.1.5. Composition Relationship: Sum of Means . . . . . . . . 9
+ 4.1.4. Mean Statistic . . . . . . . . . . . . . . . . . . . . 9
+ 4.1.5. Composition Function: Sum of Means . . . . . . . . . . 9
4.1.6. Statement of Conjecture . . . . . . . . . . . . . . . 9
 4.1.7. Justification of Composite Relationship . . . . . . . 9
 4.1.8. Sources of Error . . . . . . . . . . . . . . . . . . . 10
+ 4.1.7. Justification of the Composition Function . . . . . . 10
+ 4.1.8. Sources of Deviation from the Ground Truth . . . . . . 10
4.1.9. Specific cases where the conjecture might fail . . . . 10
4.1.10. Application of Measurement Methodology . . . . . . . . 10
5. Loss Metrics and Statistics . . . . . . . . . . . . . . . . . 11
5.1. Name:
TypePOnewayPacketLossPoisson/PeriodicStream . . . . 11
5.1.1. Metric Parameters: . . . . . . . . . . . . . . . . . . 11
5.1.2. Definition and Metric Units . . . . . . . . . . . . . 11
5.1.3. Discussion and other details . . . . . . . . . . . . . 11
5.1.4. Statistic:
TypePOnewayPacketLossEmpiricalProbability . . . 11
 5.1.5. Composition Relationship: Composition of Empirical
 Probabilities . . . . . . . . . . . . . . . . . . . . 11
+ 5.1.5. Composition Function: Composition of Empirical
+ Probabilities . . . . . . . . . . . . . . . . . . . . 12
5.1.6. Statement of Conjecture . . . . . . . . . . . . . . . 12
 5.1.7. Justification of Composite Relationship . . . . . . . 12
 5.1.8. Sources of Error . . . . . . . . . . . . . . . . . . . 12
 5.1.9. Specific cases where the conjecture might fail . . . . 12
+ 5.1.7. Justification of the Composition Function . . . . . . 12
+ 5.1.8. Sources of Deviation from the Ground Truth . . . . . . 12
+ 5.1.9. Specific cases where the conjecture might fail . . . . 13
5.1.10. Application of Measurement Methodology . . . . . . . . 13
6. Delay Variation Metrics and Statistics . . . . . . . . . . . . 13
6.1. Name:
 TypePOnewayipdvrefminPoisson/PeriodicStream . . . . 13
 6.1.1. Metric Parameters: . . . . . . . . . . . . . . . . . . 13
+ TypePOnewayipdvrefminPoisson/PeriodicStream . . . . 14
+ 6.1.1. Metric Parameters: . . . . . . . . . . . . . . . . . . 14
6.1.2. Definition and Metric Units . . . . . . . . . . . . . 14
 6.1.3. Discussion and other details . . . . . . . . . . . . . 14
 6.1.4. Statistics: Mean, Variance, Skewness, Quanitle . . . . 14
 6.1.5. Composition Relationships: . . . . . . . . . . . . . . 15
+ 6.1.3. Discussion and other details . . . . . . . . . . . . . 15
+ 6.1.4. Statistics: Mean, Variance, Skewness, Quanitle . . . . 15
+ 6.1.5. Composition Functions: . . . . . . . . . . . . . . . . 16
6.1.6. Statement of Conjecture . . . . . . . . . . . . . . . 16
 6.1.7. Justification of Composite Relationship . . . . . . . 16
 6.1.8. Sources of Error . . . . . . . . . . . . . . . . . . . 16
+ 6.1.7. Justification of the Composition Function . . . . . . 16
+ 6.1.8. Sources of Deviation from the Ground Truth . . . . . . 16
6.1.9. Specific cases where the conjecture might fail . . . . 16
6.1.10. Application of Measurement Methodology . . . . . . . . 16
7. Other Metrics and Statistics: Oneway Combined Metric . . . . 16
7.1. Metric Name: . . . . . . . . . . . . . . . . . . . . . . . 16
7.1.1. Metric Parameters: . . . . . . . . . . . . . . . . . . 16
 7.1.2. Definition and Metric Units . . . . . . . . . . . . . 16
+ 7.1.2. Definition and Metric Units . . . . . . . . . . . . . 17
7.1.3. Discussion and other details . . . . . . . . . . . . . 17
7.1.4. TypePOnewayCombosubpathesstream . . . . . . . . 17
 7.1.5. TypePOnewaycomposition . . . . . . . . . . . . . . 17
 7.1.6. TypePOnewaycomposition . . . . . . . . . . . . . . 17
+ 7.1.5. TypePOnewaycomposition . . . . . . . . . . . . . . 18
+ 7.1.6. TypePOnewaycomposition . . . . . . . . . . . . . . 18
7.1.7. Statement of Conjecture . . . . . . . . . . . . . . . 18
7.1.8. Justification of Composite Relationship . . . . . . . 18
 7.1.9. Sources of Error . . . . . . . . . . . . . . . . . . . 18
 7.1.10. Specific cases where the conjecture might fail . . . . 18
 7.1.11. Application of Measurement Methodology . . . . . . . . 18
+ 7.1.9. Sources of Error . . . . . . . . . . . . . . . . . . . 19
+ 7.1.10. Specific cases where the conjecture might fail . . . . 19
+ 7.1.11. Application of Measurement Methodology . . . . . . . . 19
8. Security Considerations . . . . . . . . . . . . . . . . . . . 19
8.1. Denial of Service Attacks . . . . . . . . . . . . . . . . 19
8.2. User Data Confidentiality . . . . . . . . . . . . . . . . 19
 8.3. Interference with the metrics . . . . . . . . . . . . . . 19
 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
 10. Security Considerations . . . . . . . . . . . . . . . . . . . 20
 11. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 20
 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 21
 13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
 13.1. Normative References . . . . . . . . . . . . . . . . . . . 21
 13.2. Informative References . . . . . . . . . . . . . . . . . . 21
 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22
 Intellectual Property and Copyright Statements . . . . . . . . . . 23
+ 8.3. Interference with the metrics . . . . . . . . . . . . . . 20
+ 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
+ 10. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 20
+ 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 21
+ 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
+ 12.1. Normative References . . . . . . . . . . . . . . . . . . . 21
+ 12.2. Informative References . . . . . . . . . . . . . . . . . . 22
+ Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 23
+ Intellectual Property and Copyright Statements . . . . . . . . . . 24
1. Contributors
Thus far, the following people have contributed useful ideas,
suggestions, or the text of sections that have been incorporated into
this memo:
 Phil Chimento
 Reza Fardid
@@ 150,33 +149,34 @@
 Al Morton
 Emile Stephan
 Lei Liang
2. Introduction
The IPPM framework RFC 2330 [RFC2330] describes two forms of metric
composition, spatial and temporal. The new composition framework
 [FRMWK] expands and further qualifies these original forms into three
 categories. This memo describes Spatial Composition, one of the
 categories of metrics under the umbrella of the composition
 framework.
+ [ID.ietfippmframeworkcompagg] expands and further qualifies these
+ original forms into three categories. This memo describes Spatial
+ Composition, one of the categories of metrics under the umbrella of
+ the composition framework.
Spatial composition encompasses the definition of performance metrics
that are applicable to a complete path, based on metrics collected on
various subpaths.
 The purpose of this memo is to define relationships that yield the
 complete path metrics using metrics of the subpaths. The
 effectiveness of such metrics is dependent on their usefulness in
 analysis and applicability with practical measurement methods.
+ The main purpose of this memo is to define the deterministic
+ functions that yield the complete path metrics using metrics of the
+ subpaths. The effectiveness of such metrics is dependent on their
+ usefulness in analysis and applicability with practical measurement
+ methods.
The relationships may involve conjecture, and [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 composition in terms of
making analysis of the path using Aframe concepts more effective,
@@ 185,74 +185,74 @@
o an analysis of how the conjecture could be incorrect.
RFC 2330 also gives an example where a conjecture that the delay of a
path is very nearly the sum of the delays of the exchanges and clouds
of the corresponding path digest. This example is particularly
relevant to those who wish to assess the performance of an Inter
domain path without direct measurement, and the performance estimate
of the complete path is related to the measured results for various
subpaths instead.
 Approximate relationships between the subpath and complete path
 metrics are useful, with knowledge of the circumstances where the
+ Approximate functions between the subpath and complete path metrics
+ are useful, with knowledge of the circumstances where the
relationships are/are not applicable. For example, we would not
expect that delay singletons from each subpath would sum to produce
an accurate estimate of a delay singleton for the complete path
(unless all the delays were essentially constant  very unlikely).
However, other delay statistics (based on a reasonable sample size)
may have a sufficiently large set of circumstances where they are
applicable.
2.1. Motivation
Oneway metrics defined in other IPPM RFCs all assume that the
measurement can be practically carried out between the source and the
destination of the interest. Sometimes there are reasons that the
measurement can not be executed from the source to the destination.
For instance, the measurement path may cross several independent
domains that have conflicting policies, measurement tools and
 methods, and measurement time slot assignment. The solution then may
 be the composition of several subpath measurements. That means each
+ methods, and measurement time assignment. The solution then may be
+ the composition of several subpath measurements. This means each
domain performs the Oneway measurement on a sub path between two
nodes that are involved in the complete path following its own
 policy, using its own measurement tools and methods, and within its
 own measurement time slot. Under the appropriate conditions, one can
+ policy, using its own measurement tools and methods, and using its
+ own measurement timing. Under the appropriate conditions, one can
combine the subpath Oneway metric results to estimate the complete
 path Oneway measurement metric with some accuracy.
+ path Oneway measurement metric with some degree of accuracy.
3. Scope, Application, and Terminology
3.1. Scope of work
 For the primary IPPM metrics (currently Loss, Delay, and Delay
 Variation), this memo gives a set of complete path metrics that can
 be composed from the same or similar subpath metrics. This means
 that the complete path metric may be composed from:
+ For the primary IPPM metrics of Loss, Delay, and Delay Variation,
+ this memo gives a set of complete path metrics that can be composed
+ from the same or similar subpath metrics. This means that the
+ complete path metric may be composed from:
o the same metric for each subpath;
o multiple metrics for each subpath (possibly one that is the same
as the complete path metric);
o a single subpath metrics that is different from the complete path
metric;
o different measurement techniques like active and passive
(recognizing that PSAMP WG will define capabilities to sample
packets to support measurement).
3.2. Application
 The new composition framework [FRMWK] requires the specification of
 the applicable circumstances for each metric. In particular, the
 application of Spatial Composition metrics are addressed as to
 whether the metric:
+ The new composition framework [ID.ietfippmframeworkcompagg]
+ requires the specification of the applicable circumstances for each
+ metric. In particular, the application of Spatial Composition
+ metrics are addressed as to whether the metric:
Requires the same test packets to traverse all subpaths, or may use
similar packets sent and collected separately in each subpath.
Requires homogeneity of measurement methodologies, or can allow a
degree of flexibility (e.g., active or passive methods produce the
"same" metric). Also, the applicable sending streams will be
specified, such as Poisson, Periodic, or both.
Needs information or access that will only be available within an
@@ 279,43 +279,43 @@
The complete path is the true path that a packet would follow as it
traverses from the packet's Source to its Destination.
Complete path metric:
The complete path metric is the Source to Destination metric that a
composed metric is estimating. A complete path metric represents the
groundtruth for a composed metric.
 Composite Metric (or Composed Metric):
+ Composed Metric:
 A composite metric is type of metric that is derived from other
 metrics principally by applying a composition relationship.
+ A composed metric is derived from other metrics principally by
+ applying a composition function.
 Composition Relationship:
+ Composition Function:
 A composition relationship is a deterministic process applied to Sub
 path metrics to derive another metric (such as a Composite metric).
+ A composition function is a deterministic process applied to Subpath
+ metrics to derive another metric (such as a Composed metric).
Subpath:
A Subpath is a portion of the complete path where at least the Sub
path Source and Destination hosts are constituents of the complete
path. We say that this subpath is "involved" in the complete path.
Subpath metrics:
A subpath path metric is an element of the process to derive a
Composite metric, quantifying some aspect of the performance a
particular subpath from its Source to Destination.
4. Oneway Delay Composition Metrics and Statistics
+4. Oneway Delay Composed Metrics and Statistics
4.1. Name: TypePFiniteOnewayDelayPoisson/PeriodicStream
This metric is a necessary element of Delay Composition metrics, and
its definition does not formally exist elsewhere in IPPM literature.
4.1.1. Metric Parameters:
o Src, the IP address of a host + Dst, the IP address of a host
o T, a time (start of test interval)
@@ 329,50 +329,63 @@
o T0, a time that MUST be selected at random from the interval [T,
T+dT] to start generating packets and taking measurements (for
Periodic Streams)
o TstampSrc, the wire time of the packet as measured at MP(Src)
o TstampDst, the wire time of the packet as measured at MP(Dst),
assigned to packets that arrive within a "reasonable" time.
 o Tmax, a maximum waiting time for packets at the destination.
+ o Tmax, a maximum waiting time for packets at the destination, set
+ sufficiently long to disambiguate packets with long delays from
+ packets that are discarded (lost), thus the distribution of delay
+ is not truncated.
4.1.2. Definition and Metric Units
Using the parameters above, we obtain the value of TypePOneway
Delay singleton as per RFC 2679 [RFC2679].
For each packet [i] that has a finite Oneway Delay (in other words,
 excluding packets which have undefined, or infinite oneway delay):
+ excluding packets which have undefined oneway delay):
TypePFiniteOnewayDelayPoisson/PeriodicStream[i] =
FiniteDelay[i] = TstampDst  TstampSrc
4.1.3. Discussion and other details
 The "TypePFiniteOnewayDelay" metric allows calculation of the
 mean statistic. This avoids the need to include lost packets in the
 sample (whose delay is undefined), and the issue with the prescribed
 assignment of infinite delay to lost packets when practical systems
 can only assign some very large value.
+ The "TypePFiniteOnewayDelay" metric permits calculation of the
+ sample mean statistic. This resolves the problem of including lost
+ packets in the sample (whose delay is undefined), and the issue with
+ the informal assignment of infinite delay to lost packets (practical
+ systems can only assign some very large value).
+
+ The FiniteOnewayDelay approach handles the problem of lost packets
+ by reducing the event space. We consider conditional statistics, and
+ estimate the mean oneway delay conditioned on the event that all
+ packets in the sample arrive at the destination (within the specified
+ waiting time, Tmax). This offers a way to make some valid statements
+ about oneway delay, and at the same time avoiding events with
+ undefined outcomes. This approach is derived from the treatment of
+ lost packets in [RFC3393], and is similar to[Y.1540] .
4.1.4. Mean Statistic
We add the following parameter:
o N, the total number of packets received at Dst (sent between T0
and Tf)
and define
+
TypePFiniteOnewayDelayMean =
N

1 \
 * > (FiniteDelay [i])
N /

i = 1
where all packets i= 1 through N have finite singleton delays.
@@ 370,21 +383,21 @@
N

1 \
 * > (FiniteDelay [i])
N /

i = 1
where all packets i= 1 through N have finite singleton delays.
4.1.5. Composition Relationship: Sum of Means
+4.1.5. Composition Function: Sum of Means
The TypePFiniteCompositeOnewayDelayMean, or CompMeanDelay for
the complete Source to Destination path can be calculated from sum of
the Mean Delays of all its S constituent subpaths.
o S, the number of subpaths involved in the complete SrcDst path.
Then the
TypePFiniteCompositeOnewayDelayMean =
@@ 392,37 +405,37 @@
CompMeanDelay = (1/S)Sum(from i=1 to S, MeanDelay[i])
4.1.6. Statement of Conjecture
The mean of a sufficiently large stream of packets measured on each
subpath during the interval [T, Tf] will be representative of the
true mean of the delay distribution (and the distributions themselves
are sufficiently independent), such that the means may be added to
produce an estimate of the complete path mean delay.
4.1.7. Justification of Composite Relationship
+4.1.7. Justification of the Composition Function
It is sometimes impractical to conduct active measurements between
every SrcDst pair. For example, it may not be possible to collect
the desired sample size in each test interval when access link speed
is limited, because of the potential for measurement traffic to
degrade the user traffic performance. The conditions on a lowspeed
access link may be understood wellenough to permit use of a small
sample size/rate, while a larger sample size/rate may be used on
other subpaths.
Also, since measurement operations have a real monetary cost, there
is value in reusing measurements where they are applicable, rather
than launching new measurements for every possible sourcedestination
pair.
4.1.8. Sources of Error
+4.1.8. Sources of Deviation from the Ground Truth
The measurement packets, each having source and destination addresses
intended for collection at edges of the subpath, may take a
different specific path through the network equipment and parallel
exchanges than packets with the source and destination addresses of
the complete path. Therefore, the subpath measurements may differ
from the performance experienced by packets on the complete path.
Multiple measurements employing sufficient subpath address pairs
might produce bounds on the extent of this error.
@@ 480,67 +493,66 @@
o L, either zero or one, where L=1 indicates loss and L=0 indicates
arrival at the destination within TstampSrc + Tmax.
5.1.3. Discussion and other details
5.1.4. Statistic: TypePOnewayPacketLossEmpiricalProbability
Given the following stream parameter
 o N, the total number of packets sent between T0 and Tf
+ o M, the total number of packets sent between T0 and Tf
We can define the Empirical Probability of Loss Statistic (Ep),
consistent with Average Loss in [RFC2680], as follows:
TypePOnewayPacketLossEmpiricalProbability =
+ Ep = (1/M)Sum(from i=1 to M, L[i])
 Ep = (1/N)Sum(from i=1 to N, L[i])

 where all packets i= 1 through N have a value for L.
+ where all packets i= 1 through M have a value for L.
5.1.5. Composition Relationship: Composition of Empirical Probabilities
+5.1.5. Composition Function: Composition of Empirical Probabilities
The TypePOnewayCompositePacketLossEmpiricalProbability, or
CompEp for the complete Source to Destination path can be calculated
by combining Ep of all its constituent subpaths (Ep1, Ep2, Ep3, ...
Epn) as
TypePOnewayCompositePacketLossEmpiricalProbability = CompEp =
1  {(1  Ep1) x (1  Ep2) x (1  Ep3) x ... x (1  Epn)}
5.1.6. Statement of Conjecture
The empirical probability of loss calculated on a sufficiently large
stream of packets measured on each subpath during the interval [T,
Tf] will be representative of the true loss probability (and the
probabilities themselves are sufficiently independent), such that the
subpath probabilities may be combined to produce an estimate of the
complete path loss probability.
5.1.7. Justification of Composite Relationship
+5.1.7. Justification of the Composition Function
It is sometimes impractical to conduct active measurements between
every SrcDst pair. For example, it may not be possible to collect
the desired sample size in each test interval when access link speed
is limited, because of the potential for measurement traffic to
degrade the user traffic performance. The conditions on a lowspeed
access link may be understood wellenough to permit use of a small
sample size/rate, while a larger sample size/rate may be used on
other subpaths.
Also, since measurement operations have a real monetary cost, there
is value in reusing measurements where they are applicable, rather
than launching new measurements for every possible sourcedestination
pair.
5.1.8. Sources of Error
+5.1.8. Sources of Deviation from the Ground Truth
The measurement packets, each having source and destination addresses
intended for collection at edges of the subpath, may take a
different specific path through the network equipment and parallel
exchanges than packets with the source and destination addresses of
the complete path. Therefore, the subpath measurements may differ
from the performance experienced by packets on the complete path.
Multiple measurements employing sufficient subpath address pairs
might produce bounds on the extent of this error.
@@ 681,33 +693,33 @@

i = 1

/ \
 ( 3/2 ) 
\ (N  1) * VarIPDVRefMin /
We define the Quantile of the IPDVRefMin sample as the value where
the specified fraction of points is less than the given value.
6.1.5. Composition Relationships:
+6.1.5. Composition Functions:
The TypePOnewayCompositeipdvrefmin for the complete
Source to Destination path can be calculated by combining statistics
of all the constituent subpaths in the following process:
 < to be provided >
+ < see [Y.1541] >
6.1.6. Statement of Conjecture
6.1.7. Justification of Composite Relationship
+6.1.7. Justification of the Composition Function
6.1.8. Sources of Error
+6.1.8. Sources of Deviation from the Ground Truth
6.1.9. Specific cases where the conjecture might fail
6.1.10. Application of Measurement Methodology
7. Other Metrics and Statistics: Oneway Combined Metric
This definition may be the common part for the definition of "Loss
Metrics/Statistics" and for the definition of "Oneway Delay
Composition Metrics and Statistics".
@@ 879,23 +890,21 @@
To discourage the kind of interference mentioned above, packet
interference checks, such as cryptographic hash, may be used.
9. IANA Considerations
Metrics defined in this memo will be registered in the IANA IPPM
METRICS REGISTRY as described in initial version of the registry RFC
4148 [RFC4148].
10. Security Considerations

11. Open Issues
+10. Open Issues
>>>>>>>>>>>>Open issue:
What is the relationship between the decomposition and composition
metrics? Should we put both kinds in one draft to make up a
framework? The motivation of decomposition is as follows:
The Oneway measurement can provide result to show what the network
performance between two end hosts is and whether it meets operator
expectations or not. It cannot provide further information to
@@ 903,83 +912,101 @@
and the destination. For instance, if the network performance is not
acceptable in terms of the Oneway measurement, in which part of the
network the engineers should put their efforts. This question can to
be answered by decompose the Oneway measurement to subpath
measurement to investigate the performance of different part of the
network.
Editor's Questions for clarification: What additional information
would be provided to the decomposition process, beyond the
measurement of the complete path?

Is the decomposition described above intended to estimate a metric
for some/all disjoint subpaths involved in the complete path?
+ >>>>>>>>>>>>>>>>>>RESOLUTION: treat this topic in a seperate memo
+
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>OPEN Issue
Section 7 defines a new type of metric, a "combination" of metrics
for oneway delay and packet loss. The purpose of this metric is to
link these two primary metrics in a convenient way.
Readers are asked to comment on the efficiency of the combination
metric.
+ >>>>>>>>>>>>>>>>>RESOLUTION: If a delay singleton is recorded as
+ having "undefined" delay when the packet does not arrive within the
+ waiting time Tmax, then this information is sufficient to determine
+ the fraction of lost packets in the sample, and the additional loss
+ indication of this combo is not needed.
+
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> OPEN Issue
How can we introduce multicast metrics here, without causing too much
confusion? Should the multicast version of this draft wait until the
Unicast concepts are stable (or maybe appear in a separate draft)?
12. Acknowledgements
+ >>>>>>>>>>>>>>>>RESOLUTION: Yes and Yes.
13. References
+11. Acknowledgements
13.1. Normative References
+12. References
 [FRMWK] Morton, A. and S.Van Den Berghe, "Framework for Metric
 Composition", February 2006.
+12.1. Normative References
+
+ [ID.ietfippmframeworkcompagg]
+ Morton, A. and S. Berghe, "Framework for Metric
+ Composition", draftietfippmframeworkcompagg00 (work
+ in progress), February 2006.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[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 Oneway
Delay Metric for IPPM", RFC 2679, September 1999.
[RFC2680] Almes, G., Kalidindi, S., and M. Zekauskas, "A Oneway
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.
[RFC4148] Stephan, E., "IP Performance Metrics (IPPM) Metrics
Registry", BCP 108, RFC 4148, August 2005.
13.2. Informative References
+12.2. Informative References
[ID.stephanippmmultimetrics]
Stephan, E., "IP Performance Metrics (IPPM) for spatial
and multicast", draftstephanippmmultimetrics02 (work
in progress), October 2005.
[Y.1540] ITUT Recommendation Y.1540, "Internet protocol data
communication service  IP packet transfer and
availability performance parameters", December 2002.
+ [Y.1541] ITUT Recommendation Y.1540, "Network Performance
+ Objectives for IPbased Services", February 2006.
+
Authors' Addresses
Al Morton
AT&T Labs
200 Laurel Avenue South
Middletown,, NJ 07748
USA
Phone: +1 732 420 1571
Fax: +1 732 368 1192