draft-ietf-ippm-spatial-composition-09.txt   draft-ietf-ippm-spatial-composition-10.txt 
Network Working Group A. Morton Network Working Group A. Morton
Internet-Draft AT&T Labs Internet-Draft AT&T Labs
Intended status: Standards Track E. Stephan Intended status: Standards Track E. Stephan
Expires: December 23, 2009 France Telecom Division R&D Expires: April 21, 2010 France Telecom Division R&D
June 21, 2009 October 18, 2009
Spatial Composition of Metrics Spatial Composition of Metrics
draft-ietf-ippm-spatial-composition-09 draft-ietf-ippm-spatial-composition-10
Status of this Memo Status of this Memo
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4.1. Name: Type-P . . . . . . . . . . . . . . . . . . . . . . . 8 4.1. Name: Type-P . . . . . . . . . . . . . . . . . . . . . . . 8
4.1.1. Metric Parameters . . . . . . . . . . . . . . . . . . 8 4.1.1. Metric Parameters . . . . . . . . . . . . . . . . . . 8
4.1.2. Definition and Metric Units . . . . . . . . . . . . . 9 4.1.2. Definition and Metric Units . . . . . . . . . . . . . 9
4.1.3. Discussion and other details . . . . . . . . . . . . . 9 4.1.3. Discussion and other details . . . . . . . . . . . . . 9
4.1.4. Statistic: . . . . . . . . . . . . . . . . . . . . . . 9 4.1.4. Statistic: . . . . . . . . . . . . . . . . . . . . . . 9
4.1.5. Composition Function . . . . . . . . . . . . . . . . . 9 4.1.5. Composition Function . . . . . . . . . . . . . . . . . 9
4.1.6. Statement of Conjecture and Assumptions . . . . . . . 9 4.1.6. Statement of Conjecture and Assumptions . . . . . . . 9
4.1.7. Justification of the Composition Function . . . . . . 10 4.1.7. Justification of the Composition Function . . . . . . 10
4.1.8. Sources of Deviation from the Ground Truth . . . . . . 10 4.1.8. Sources of Deviation from the Ground Truth . . . . . . 10
4.1.9. Specific cases where the conjecture might fail . . . . 11 4.1.9. Specific cases where the conjecture might fail . . . . 11
4.1.10. Application of Measurement Methodology . . . . . . . . 12 4.1.10. Application of Measurement Methodology . . . . . . . . 11
5. One-way Delay Composed Metrics and Statistics . . . . . . . . 12 5. One-way Delay Composed Metrics and Statistics . . . . . . . . 12
5.1. Name: 5.1. Name:
Type-P-Finite-One-way-Delay-Poisson/Periodic-Stream . . . 12 Type-P-Finite-One-way-Delay-Poisson/Periodic-Stream . . . 12
5.1.1. Metric Parameters . . . . . . . . . . . . . . . . . . 12 5.1.1. Metric Parameters . . . . . . . . . . . . . . . . . . 12
5.1.2. Definition and Metric Units . . . . . . . . . . . . . 12 5.1.2. Definition and Metric Units . . . . . . . . . . . . . 12
5.1.3. Discussion and other details . . . . . . . . . . . . . 13 5.1.3. Discussion and other details . . . . . . . . . . . . . 12
5.1.4. Statistic: . . . . . . . . . . . . . . . . . . . . . . 13 5.1.4. Statistic: . . . . . . . . . . . . . . . . . . . . . . 13
5.2. Name: Type-P-Finite-Composite-One-way-Delay-Mean . . . . . 13 5.2. Name: Type-P-Finite-Composite-One-way-Delay-Mean . . . . . 13
5.2.1. Metric Parameters . . . . . . . . . . . . . . . . . . 13 5.2.1. Metric Parameters . . . . . . . . . . . . . . . . . . 13
5.2.2. Definition and Metric Units of the Mean Statistic . . 13 5.2.2. Definition and Metric Units of the Mean Statistic . . 13
5.2.3. Discussion and other details . . . . . . . . . . . . . 14 5.2.3. Discussion and other details . . . . . . . . . . . . . 14
5.2.4. Statistic: . . . . . . . . . . . . . . . . . . . . . . 14 5.2.4. Statistic: . . . . . . . . . . . . . . . . . . . . . . 14
5.2.5. Composition Function: Sum of Means . . . . . . . . . . 14 5.2.5. Composition Function: Sum of Means . . . . . . . . . . 14
5.2.6. Statement of Conjecture and Assumptions . . . . . . . 14 5.2.6. Statement of Conjecture and Assumptions . . . . . . . 14
5.2.7. Justification of the Composition Function . . . . . . 15 5.2.7. Justification of the Composition Function . . . . . . 14
5.2.8. Sources of Deviation from the Ground Truth . . . . . . 15 5.2.8. Sources of Deviation from the Ground Truth . . . . . . 14
5.2.9. Specific cases where the conjecture might fail . . . . 15 5.2.9. Specific cases where the conjecture might fail . . . . 15
5.2.10. Application of Measurement Methodology . . . . . . . . 15 5.2.10. Application of Measurement Methodology . . . . . . . . 15
5.3. Name: Type-P-Finite-Composite-One-way-Delay-Minimum . . . 15 5.3. Name: Type-P-Finite-Composite-One-way-Delay-Minimum . . . 15
5.3.1. Metric Parameters . . . . . . . . . . . . . . . . . . 15 5.3.1. Metric Parameters . . . . . . . . . . . . . . . . . . 15
5.3.2. Definition and Metric Units of the Minimum 5.3.2. Definition and Metric Units of the Minimum
Statistic . . . . . . . . . . . . . . . . . . . . . . 15 Statistic . . . . . . . . . . . . . . . . . . . . . . 15
5.3.3. Discussion and other details . . . . . . . . . . . . . 16 5.3.3. Discussion and other details . . . . . . . . . . . . . 16
5.3.4. Statistic: . . . . . . . . . . . . . . . . . . . . . . 16 5.3.4. Statistic: . . . . . . . . . . . . . . . . . . . . . . 16
5.3.5. Composition Function: Sum of Minima . . . . . . . . . 16 5.3.5. Composition Function: Sum of Minima . . . . . . . . . 16
5.3.6. Statement of Conjecture and Assumptions . . . . . . . 16 5.3.6. Statement of Conjecture and Assumptions . . . . . . . 16
5.3.7. Justification of the Composition Function . . . . . . 17 5.3.7. Justification of the Composition Function . . . . . . 16
5.3.8. Sources of Deviation from the Ground Truth . . . . . . 17 5.3.8. Sources of Deviation from the Ground Truth . . . . . . 16
5.3.9. Specific cases where the conjecture might fail . . . . 17 5.3.9. Specific cases where the conjecture might fail . . . . 17
5.3.10. Application of Measurement Methodology . . . . . . . . 17 5.3.10. Application of Measurement Methodology . . . . . . . . 17
6. Loss Metrics and Statistics . . . . . . . . . . . . . . . . . 17 6. Loss Metrics and Statistics . . . . . . . . . . . . . . . . . 17
6.1. Type-P-Composite-One-way-Packet-Loss-Empirical-Probability 17 6.1. Type-P-Composite-One-way-Packet-Loss-Empirical-Probability 17
6.1.1. Metric Parameters: . . . . . . . . . . . . . . . . . . 17 6.1.1. Metric Parameters: . . . . . . . . . . . . . . . . . . 17
6.1.2. Definition and Metric Units . . . . . . . . . . . . . 17 6.1.2. Definition and Metric Units . . . . . . . . . . . . . 17
6.1.3. Discussion and other details . . . . . . . . . . . . . 17 6.1.3. Discussion and other details . . . . . . . . . . . . . 17
6.1.4. Statistic: 6.1.4. Statistic:
Type-P-One-way-Packet-Loss-Empirical-Probability . . . 18 Type-P-One-way-Packet-Loss-Empirical-Probability . . . 17
6.1.5. Composition Function: Composition of Empirical 6.1.5. Composition Function: Composition of Empirical
Probabilities . . . . . . . . . . . . . . . . . . . . 18 Probabilities . . . . . . . . . . . . . . . . . . . . 18
6.1.6. Statement of Conjecture and Assumptions . . . . . . . 18 6.1.6. Statement of Conjecture and Assumptions . . . . . . . 18
6.1.7. Justification of the Composition Function . . . . . . 18 6.1.7. Justification of the Composition Function . . . . . . 18
6.1.8. Sources of Deviation from the Ground Truth . . . . . . 19 6.1.8. Sources of Deviation from the Ground Truth . . . . . . 18
6.1.9. Specific cases where the conjecture might fail . . . . 19 6.1.9. Specific cases where the conjecture might fail . . . . 18
6.1.10. Application of Measurement Methodology . . . . . . . . 19 6.1.10. Application of Measurement Methodology . . . . . . . . 19
7. Delay Variation Metrics and Statistics . . . . . . . . . . . . 19 7. Delay Variation Metrics and Statistics . . . . . . . . . . . . 19
7.1. Name: Type-P-One-way-pdv-refmin-Poisson/Periodic-Stream . 19 7.1. Name: Type-P-One-way-pdv-refmin-Poisson/Periodic-Stream . 19
7.1.1. Metric Parameters: . . . . . . . . . . . . . . . . . . 19 7.1.1. Metric Parameters: . . . . . . . . . . . . . . . . . . 19
7.1.2. Definition and Metric Units . . . . . . . . . . . . . 20 7.1.2. Definition and Metric Units . . . . . . . . . . . . . 20
7.1.3. Discussion and other details . . . . . . . . . . . . . 20 7.1.3. Discussion and other details . . . . . . . . . . . . . 20
7.1.4. Statistics: Mean, Variance, Skewness, Quanitle . . . . 20 7.1.4. Statistics: Mean, Variance, Skewness, Quanitle . . . . 20
7.1.5. Composition Functions: . . . . . . . . . . . . . . . . 21 7.1.5. Composition Functions: . . . . . . . . . . . . . . . . 21
7.1.6. Statement of Conjecture and Assumptions . . . . . . . 22 7.1.6. Statement of Conjecture and Assumptions . . . . . . . 22
7.1.7. Justification of the Composition Function . . . . . . 22 7.1.7. Justification of the Composition Function . . . . . . 22
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elements on the complete path. For example, the network exchange elements on the complete path. For example, the network exchange
points might be excluded unless a cooperative measurement is points might be excluded unless a cooperative measurement is
conducted. In this example, test packets on the previous sub-path conducted. In this example, test packets on the previous sub-path
are received just before the exchange point and test packets on the are received just before the exchange point and test packets on the
next sub-path are injected just after the same exchange point. next sub-path are injected just after the same exchange point.
Clearly, the set of sub-path measurements SHOULD cover all critical Clearly, the set of sub-path measurements SHOULD cover all critical
network elements in the complete path. network elements in the complete path.
4.1.8.4. Absence of route 4.1.8.4. Absence of route
******************** At a specific point in time, no viable route exists between the
complete path source and destination. The routes selected for one or
Note: this section may be expressing the point of 4.1.8.1 in more sub-paths therefore differs from the complete path.
different words - its status is TBD. Consequently, spatial composition may produce finite estimation of a
ground truth metric between a source and a destination, even when the
******************** route between them is undefined.
Sub-path destination addresses and complete path addresses do not
belong to the same network. Therefore routes selected to reach each
sub-path destinations differ from the route that would be selected to
reach the destination address of the complete path. Consequently
spatial composition may produce finite estimation of a ground true
metric between a source Src and a destination Dst when the route
between Src and Dst is undefined.
4.1.9. Specific cases where the conjecture might fail 4.1.9. Specific cases where the conjecture might fail
This section is unique for most metrics (see the metric-specific This section is unique for most metrics (see the metric-specific
sections). sections).
For delay-related metrics, One-way delay always depends on packet For delay-related metrics, One-way delay always depends on packet
size and link capacity, since it is measured in [RFC2679] from first size and link capacity, since it is measured in [RFC2679] from first
bit to last bit. If the size of an IP packet changes (due to bit to last bit. If the size of an IP packet changes (due to
encapsulation for security reasons), this will influence delay encapsulation for security reasons), this will influence delay
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objective is to estimate a quantile of the complete path delay objective is to estimate a quantile of the complete path delay
variation distribution. The composed quantile will be estimated variation distribution. The composed quantile will be estimated
using information from the sub-path delay variation distributions. using information from the sub-path delay variation distributions.
7.1.5.1. Approximate Convolution 7.1.5.1. Approximate Convolution
The Type-P-Finite-One-way-Delay-Poisson/Periodic-Stream samples from The Type-P-Finite-One-way-Delay-Poisson/Periodic-Stream samples from
each sub-path are summarized as a histogram with 1 ms bins each sub-path are summarized as a histogram with 1 ms bins
representing the one-way delay distribution. representing the one-way delay distribution.
From [TBP], the distribution of the sum of independent random From [Stats], the distribution of the sum of independent random
variables can be derived using the relation: variables can be derived using the relation:
Type-P-Composite-One-way-pdv-refmin-quantile-a = Type-P-Composite-One-way-pdv-refmin-quantile-a =
/ / / /
P(X + Y + Z <= a) = | | P(X <= a-y-z) * P(Y = y) * P(Z = z) dy dz P(X + Y + Z <= a) = | | P(X <= a-y-z) * P(Y = y) * P(Z = z) dy dz
/ / / /
z y z y
where X, Y, and Z are random variables representing the delay where X, Y, and Z are random variables representing the delay
variation distributions of the sub-paths of the complete path (in variation distributions of the sub-paths of the complete path (in
this case, there are three sub-paths), and a is the quantile of this case, there are three sub-paths), and a is the quantile of
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Thanks Will. Thanks Will.
11. Issues (Open and Closed) 11. Issues (Open and Closed)
>>>>>>>>>>>>Issue: >>>>>>>>>>>>Issue:
Is Section 4.1.8.4 really describing a new error case, about Is Section 4.1.8.4 really describing a new error case, about
Alternate Routing? Or does Section 4.1.8.1 on sub-path differences Alternate Routing? Or does Section 4.1.8.1 on sub-path differences
cover it all? cover it all?
RESOLUTION: The section was re-worded in -10 version to make the
topic, Absence of a real Route between the Src and Dst, more clear.
>>>>>>>>>>>>
>>>>>>>>>>>>Issue: >>>>>>>>>>>>Issue:
What is the relationship between the decomposition and composition What is the relationship between the decomposition and composition
metrics? Should we put both kinds in one draft to make up a metrics? Should we put both kinds in one draft to make up a
framework? The motivation of decomposition is as follows: framework? The motivation of decomposition is as follows:
The One-way measurement can provide result to show what the network The One-way measurement can provide result to show what the network
performance between two end hosts is and whether it meets operator performance between two end hosts is and whether it meets operator
expectations or not. It cannot provide further information to expectations or not. It cannot provide further information to
engineers where and how to improve the performance between the source engineers where and how to improve the performance between the source
skipping to change at page 26, line 13 skipping to change at page 26, line 17
>>>>>>>>>>>>>>>>RESOLUTION: No and Yes. >>>>>>>>>>>>>>>>RESOLUTION: No and Yes.
12. Acknowledgements 12. Acknowledgements
13. References 13. References
13.1. Normative References 13.1. Normative References
[I-D.ietf-ippm-framework-compagg] [I-D.ietf-ippm-framework-compagg]
Morton, A., "Framework for Metric Composition", Morton, A., "Framework for Metric Composition",
draft-ietf-ippm-framework-compagg-07 (work in progress), draft-ietf-ippm-framework-compagg-08 (work in progress),
October 2008. June 2009.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[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.
[RFC2679] Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way [RFC2679] Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way
Delay Metric for IPPM", RFC 2679, September 1999. Delay Metric for IPPM", RFC 2679, September 1999.
skipping to change at page 26, line 41 skipping to change at page 26, line 45
November 2002. November 2002.
[RFC4148] Stephan, E., "IP Performance Metrics (IPPM) Metrics [RFC4148] Stephan, E., "IP Performance Metrics (IPPM) Metrics
Registry", BCP 108, RFC 4148, August 2005. Registry", BCP 108, RFC 4148, August 2005.
13.2. Informative References 13.2. Informative References
[I-D.ietf-ippm-multimetrics] [I-D.ietf-ippm-multimetrics]
Stephan, E., Liang, L., and A. Morton, "IP Performance Stephan, E., Liang, L., and A. Morton, "IP Performance
Metrics (IPPM) for spatial and multicast", Metrics (IPPM) for spatial and multicast",
draft-ietf-ippm-multimetrics-11 (work in progress), draft-ietf-ippm-multimetrics-12 (work in progress),
April 2009. September 2009.
[Stats] McGraw-Hill NY NY, "Introduction to the Theory of
Statistics, 3rd Edition,", 1974.
[Y.1540] ITU-T Recommendation Y.1540, "Internet protocol data [Y.1540] ITU-T Recommendation Y.1540, "Internet protocol data
communication service - IP packet transfer and communication service - IP packet transfer and
availability performance parameters", December 2002. availability performance parameters", December 2002.
[Y.1541] ITU-T Recommendation Y.1541, "Network Performance [Y.1541] ITU-T Recommendation Y.1541, "Network Performance
Objectives for IP-based Services", February 2006. Objectives for IP-based Services", February 2006.
Index Index
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