draft-ietf-ippm-spatial-composition-11.txt | draft-ietf-ippm-spatial-composition-12.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: October 16, 2010 France Telecom Division R&D | Expires: December 1, 2010 France Telecom Division R&D | |||

April 14, 2010 | May 30, 2010 | |||

Spatial Composition of Metrics | Spatial Composition of Metrics | |||

draft-ietf-ippm-spatial-composition-11 | draft-ietf-ippm-spatial-composition-12 | |||

Abstract | Abstract | |||

This memo utilizes IPPM metrics that are applicable to both complete | This memo utilizes IP Performance Metrics that are applicable to both | |||

paths and sub-paths, and defines relationships to compose a complete | complete paths and sub-paths, and defines relationships to compose a | |||

path metric from the sub-path metrics with some accuracy w.r.t. the | complete path metric from the sub-path metrics with some accuracy | |||

actual metrics. This is called Spatial Composition in RFC 2330. The | w.r.t. the actual metrics. This is called Spatial Composition in RFC | |||

memo refers to the Framework for Metric Composition, and provides | 2330. The memo refers to the Framework for Metric Composition, and | |||

background and motivation for combining metrics to derive others. | provides background and motivation for combining metrics to derive | |||

The descriptions of several composed metrics and statistics follow. | others. The descriptions of several composed metrics and statistics | |||

follow. | ||||

Requirements Language | Requirements Language | |||

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", | The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", | |||

"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this | "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this | |||

document are to be interpreted as described in RFC 2119 [RFC2119]. | document are to be interpreted as described in RFC 2119 [RFC2119]. | |||

In this memo, the characters "<=" should be read as "less than or | In this memo, the characters "<=" should be read as "less than or | |||

equal to" and ">=" as "greater than or equal to". | equal to" and ">=" as "greater than or equal to". | |||

skipping to change at page 1, line 46 | skipping to change at page 1, line 47 | |||

Internet-Drafts are working documents of the Internet Engineering | Internet-Drafts are working documents of the Internet Engineering | |||

Task Force (IETF). Note that other groups may also distribute | Task Force (IETF). Note that other groups may also distribute | |||

working documents as Internet-Drafts. The list of current Internet- | working documents as Internet-Drafts. The list of current Internet- | |||

Drafts is at http://datatracker.ietf.org/drafts/current/. | Drafts is at http://datatracker.ietf.org/drafts/current/. | |||

Internet-Drafts are draft documents valid for a maximum of six months | Internet-Drafts are draft documents valid for a maximum of six months | |||

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." | |||

This Internet-Draft will expire on October 16, 2010. | This Internet-Draft will expire on December 1, 2010. | |||

Copyright Notice | Copyright Notice | |||

Copyright (c) 2010 IETF Trust and the persons identified as the | Copyright (c) 2010 IETF Trust and the persons identified as the | |||

document authors. All rights reserved. | document authors. All rights reserved. | |||

This document is subject to BCP 78 and the IETF Trust's Legal | This document is subject to BCP 78 and the IETF Trust's Legal | |||

Provisions Relating to IETF Documents | Provisions Relating to IETF Documents | |||

(http://trustee.ietf.org/license-info) in effect on the date of | (http://trustee.ietf.org/license-info) in effect on the date of | |||

publication of this document. Please review these documents | publication of this document. Please review these documents | |||

carefully, as they describe your rights and restrictions with respect | carefully, as they describe your rights and restrictions with respect | |||

skipping to change at page 3, line 25 | skipping to change at page 3, line 25 | |||

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 . . . . . . . . 11 | 4.1.10. Application of Measurement Methodology . . . . . . . . 12 | |||

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 . . . . . . . . . . . . . 12 | 5.1.3. Discussion and other details . . . . . . . . . . . . . 13 | |||

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 . . . . . . 14 | 5.2.7. Justification of the Composition Function . . . . . . 15 | |||

5.2.8. Sources of Deviation from the Ground Truth . . . . . . 14 | 5.2.8. Sources of Deviation from the Ground Truth . . . . . . 15 | |||

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 . . . . . . 16 | 5.3.7. Justification of the Composition Function . . . . . . 17 | |||

5.3.8. Sources of Deviation from the Ground Truth . . . . . . 16 | 5.3.8. Sources of Deviation from the Ground Truth . . . . . . 17 | |||

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 . . . 17 | Type-P-One-way-Packet-Loss-Empirical-Probability . . . 18 | |||

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 . . . . . . 18 | 6.1.8. Sources of Deviation from the Ground Truth . . . . . . 19 | |||

6.1.9. Specific cases where the conjecture might fail . . . . 18 | 6.1.9. Specific cases where the conjecture might fail . . . . 19 | |||

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 | |||

skipping to change at page 4, line 43 | skipping to change at page 4, line 43 | |||

8. Security Considerations . . . . . . . . . . . . . . . . . . . 23 | 8. Security Considerations . . . . . . . . . . . . . . . . . . . 23 | |||

8.1. Denial of Service Attacks . . . . . . . . . . . . . . . . 23 | 8.1. Denial of Service Attacks . . . . . . . . . . . . . . . . 23 | |||

8.2. User Data Confidentiality . . . . . . . . . . . . . . . . 23 | 8.2. User Data Confidentiality . . . . . . . . . . . . . . . . 23 | |||

8.3. Interference with the metrics . . . . . . . . . . . . . . 24 | 8.3. Interference with the metrics . . . . . . . . . . . . . . 24 | |||

9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24 | 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24 | |||

10. Acknowlegements . . . . . . . . . . . . . . . . . . . . . . . 24 | 10. Acknowlegements . . . . . . . . . . . . . . . . . . . . . . . 24 | |||

11. Issues (Open and Closed) . . . . . . . . . . . . . . . . . . . 24 | 11. Issues (Open and Closed) . . . . . . . . . . . . . . . . . . . 24 | |||

12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 26 | 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 26 | |||

13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 26 | 13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 26 | |||

13.1. Normative References . . . . . . . . . . . . . . . . . . . 26 | 13.1. Normative References . . . . . . . . . . . . . . . . . . . 26 | |||

13.2. Informative References . . . . . . . . . . . . . . . . . . 26 | 13.2. Informative References . . . . . . . . . . . . . . . . . . 27 | |||

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 | Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 | |||

Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 27 | Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 27 | |||

1. Contributors | 1. Contributors | |||

Thus far, the following people have contributed useful ideas, | Thus far, the following people have contributed useful ideas, | |||

suggestions, or the text of sections that have been incorporated into | suggestions, or the text of sections that have been incorporated into | |||

this memo: | this memo: | |||

- Phil Chimento <vze275m9@verizon.net> | - Phil Chimento <vze275m9@verizon.net> | |||

skipping to change at page 6, line 33 | skipping to change at page 6, line 33 | |||

an accurate estimate of a delay singleton for the complete path | an accurate estimate of a delay singleton for the complete path | |||

(unless all the delays were essentially constant - very unlikely). | (unless all the delays were essentially constant - very unlikely). | |||

However, other delay statistics (based on a reasonable sample size) | However, other delay statistics (based on a reasonable sample size) | |||

may have a sufficiently large set of circumstances where they are | may have a sufficiently large set of circumstances where they are | |||

applicable. | applicable. | |||

2.1. Motivation | 2.1. Motivation | |||

One-way metrics defined in other IPPM RFCs all assume that the | One-way metrics defined in other IPPM RFCs all assume that the | |||

measurement can be practically carried out between the source and the | measurement can be practically carried out between the source and the | |||

destination of the interest. Sometimes there are reasons that the | destination of interest. Sometimes there are reasons that the | |||

measurement can not be executed from the source to the destination. | measurement can not be executed from the source to the destination. | |||

For instance, the measurement path may cross several independent | For instance, the measurement path may cross several independent | |||

domains that have conflicting policies, measurement tools and | domains that have conflicting policies, measurement tools and | |||

methods, and measurement time assignment. The solution then may be | methods, and measurement time assignment. The solution then may be | |||

the composition of several sub-path measurements. This means each | the composition of several sub-path measurements. This means each | |||

domain performs the One-way measurement on a sub path between two | domain performs the One-way measurement on a sub path between two | |||

nodes that are involved in the complete path following its own | nodes that are involved in the complete path following its own | |||

policy, using its own measurement tools and methods, and using its | policy, using its own measurement tools and methods, and using its | |||

own measurement timing. Under the appropriate conditions, one can | own measurement timing. Under the appropriate conditions, one can | |||

combine the sub-path One-way metric results to estimate the complete | combine the sub-path One-way metric results to estimate the complete | |||

skipping to change at page 7, line 19 | skipping to change at page 7, line 19 | |||

function may utilize: | function may utilize: | |||

o the same metric for each sub-path; | o the same metric for each sub-path; | |||

o multiple metrics for each sub-path (possibly one that is the same | o multiple metrics for each sub-path (possibly one that is the same | |||

as the complete path metric); | as the complete path metric); | |||

o a single sub-path metric that is different from the complete path | o a single sub-path metric that is different from the complete path | |||

metric; | metric; | |||

o different measurement techniques like active and passive | o different measurement techniques like active [RFC2330], [RFC3432] | |||

(recognizing that PSAMP WG will define capabilities to sample | and passive [RFC5474]. | |||

packets to support measurement). | ||||

We note a possibility: Using a complete path metric and all but one | We note a possibility: Using a complete path metric and all but one | |||

sub-path metric to infer the performance of the missing sub-path, | sub-path metric to infer the performance of the missing sub-path, | |||

especially when the "last" sub-path metric is missing. However, such | especially when the "last" sub-path metric is missing. However, such | |||

de-composition calculations, and the corresponding set of issues they | de-composition calculations, and the corresponding set of issues they | |||

raise, are beyond the scope of this memo. | raise, are beyond the scope of this memo. | |||

3.2. Application | 3.2. Application | |||

The new composition framework [RFC5835] requires the specification of | The new composition framework [RFC5835] requires the specification of | |||

skipping to change at page 9, line 4 | skipping to change at page 8, line 49 | |||

4.1.1. Metric Parameters | 4.1.1. Metric Parameters | |||

o Src, the IP address of a host | o Src, the IP address of a host | |||

o Dst, the IP address of a host | o Dst, the IP address of a host | |||

o T, a time (start of test interval) | o T, a time (start of test interval) | |||

o Tf, a time (end of test interval) | o Tf, a time (end of test interval) | |||

o lambda, a rate in reciprocal seconds (for Poisson Streams) | ||||

o lambda, a rate in reciprocal seconds (for Poisson Streams) | ||||

o incT, the nominal duration of inter-packet interval, first bit to | o incT, the nominal duration of inter-packet interval, first bit to | |||

first bit (for Periodic Streams) | first bit (for Periodic Streams) | |||

o T0, a time that MUST be selected at random from the interval [T, | o T0, a time that MUST be selected at random from the interval [T, | |||

T+dT] to start generating packets and taking measurements (for | T+dT] to start generating packets and taking measurements (for | |||

Periodic Streams) | Periodic Streams) | |||

o TstampSrc, the wire time of the packet as measured at MP(Src) | 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), | o TstampDst, the wire time of the packet as measured at MP(Dst), | |||

skipping to change at page 9, line 30 | skipping to change at page 9, line 28 | |||

packets that are discarded (lost), thus the distribution of delay | packets that are discarded (lost), thus the distribution of delay | |||

is not truncated. | is not truncated. | |||

o M, the total number of packets sent between T0 and Tf | o M, the total number of packets sent between T0 and Tf | |||

o N, the total number of packets received at Dst (sent between T0 | o N, the total number of packets received at Dst (sent between T0 | |||

and Tf) | and Tf) | |||

o S, the number of sub-paths involved in the complete Src-Dst path | o S, the number of sub-paths involved in the complete Src-Dst path | |||

o Type-P, as defined in [RFC2330], which includes any field that may | ||||

affect a packet's treatment as it traverses network | ||||

4.1.2. Definition and Metric Units | 4.1.2. Definition and Metric Units | |||

This section is unique for every metric. | This section is unique for every metric. | |||

4.1.3. Discussion and other details | 4.1.3. Discussion and other details | |||

This section is unique for every metric. | This section is unique for every metric. | |||

4.1.4. Statistic: | 4.1.4. Statistic: | |||

skipping to change at page 11, line 34 | skipping to change at page 11, line 34 | |||

ground truth metric between a source and a destination, even when the | ground truth metric between a source and a destination, even when the | |||

route between them is undefined. | route between them 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 on route (due | |||

encapsulation for security reasons), this will influence delay | to encapsulation), this can influence delay performance. However, | |||

performance. | the main error source may be the additional processing associated | |||

with encapsulation and encryption/decryption if not experienced or | ||||

accounted for in sub-path measurements. | ||||

Fragmentation is a major issue for compostion accuracy, since all | Fragmentation is a major issue for composition accuracy, since all | |||

metrics require all fragments to arrive before proceeding, and | metrics require all fragments to arrive before proceeding, and | |||

fragmented complete path performance is likely to be different from | fragmented complete path performance is likely to be different from | |||

performance with non-fragmented packets and composed metrics based on | performance with non-fragmented packets and composed metrics based on | |||

non-fragmented sub-path measurements. | non-fragmented sub-path measurements. | |||

Highly manipulated routing can cause measurement error if not | ||||

expected and compensated. For example, policy-based MPLS routing | ||||

could modify the class of service for the sub-paths and complete | ||||

path. | ||||

4.1.10. Application of Measurement Methodology | 4.1.10. Application of Measurement Methodology | |||

The methodology: | The methodology: | |||

SHOULD use similar packets sent and collected separately in each sub- | SHOULD use similar packets sent and collected separately in each sub- | |||

path. | path, where "similar" in this case means that the Type-P contains as | |||

many equal attributes as possible, while recognizing that there will | ||||

be differences. Note that Type-P includes stream characteristics | ||||

(e.g., Poisson, Periodic). | ||||

Allows a degree of flexibility regarding test stream generation | Allows a degree of flexibility regarding test stream generation | |||

(e.g., active or passive methods can produce an equivalent result, | (e.g., active or passive methods can produce an equivalent result, | |||

but the lack of control over the source, timing and correlation of | but the lack of control over the source, timing and correlation of | |||

passive measurements is much more challenging). | passive measurements is much more challenging). | |||

Poisson and/or Periodic streams are RECOMMENDED. | Poisson and/or Periodic streams are RECOMMENDED. | |||

Applies to both Inter-domain and Intra-domain composition. | Applies to both Inter-domain and Intra-domain composition. | |||

skipping to change at page 14, line 30 | skipping to change at page 14, line 45 | |||

Then the | Then the | |||

Type-P-Finite-Composite-One-way-Delay-Mean = | Type-P-Finite-Composite-One-way-Delay-Mean = | |||

S | S | |||

--- | --- | |||

\ | \ | |||

CompMeanDelay = > (MeanDelay [s]) | CompMeanDelay = > (MeanDelay [s]) | |||

/ | / | |||

--- | --- | |||

s = 1 | s = 1 | |||

where sub-paths s = 1 to S are invloved in the complete path. | where sub-paths s = 1 to S are involved in the complete path. | |||

5.2.6. Statement of Conjecture and Assumptions | 5.2.6. Statement of Conjecture and Assumptions | |||

The mean of a sufficiently large stream of packets measured on each | The mean of a sufficiently large stream of packets measured on each | |||

sub-path during the interval [T, Tf] will be representative of the | sub-path during the interval [T, Tf] will be representative of the | |||

ground truth mean of the delay distribution (and the distributions | ground truth mean of the delay distribution (and the distributions | |||

themselves are sufficiently independent), such that the means may be | themselves are sufficiently independent), such that the means may be | |||

added to produce an estimate of the complete path mean delay. | added to produce an estimate of the complete path mean delay. | |||

It is assumed that the one-way delay distributions of the sub-paths | It is assumed that the one-way delay distributions of the sub-paths | |||

and the complete path are continuous. The mean of bi-modal | and the complete path are continuous. The mean of multi-modal | |||

distributions have the unfortunate property that such a value may | distributions have the unfortunate property that such a value may | |||

never occur. | never occur. | |||

5.2.7. Justification of the Composition Function | 5.2.7. Justification of the Composition Function | |||

See the common section. | See the common section. | |||

5.2.8. Sources of Deviation from the Ground Truth | 5.2.8. Sources of Deviation from the Ground Truth | |||

See the common section. | See the common section. | |||

5.2.9. Specific cases where the conjecture might fail | 5.2.9. Specific cases where the conjecture might fail | |||

If any of the sub-path distributions are bimodal, then the measured | If any of the sub-path distributions are multi-modal, then the | |||

means may not be stable, and in this case the mean will not be a | measured means may not be stable, and in this case the mean will not | |||

particularly useful statistic when describing the delay distribution | be a particularly useful statistic when describing the delay | |||

of the complete path. | distribution of the complete path. | |||

The mean may not be sufficiently robust statistic to produce a | The mean may not be sufficiently robust statistic to produce a | |||

reliable estimate, or to be useful even if it can be measured. | reliable estimate, or to be useful even if it can be measured. | |||

If a link contributing non-negligible delay is erroneously included | If a link contributing non-negligible delay is erroneously included | |||

or excluded, the composition will be in error. | or excluded, the composition will be in error. | |||

5.2.10. Application of Measurement Methodology | 5.2.10. Application of Measurement Methodology | |||

The requirements of the common section apply here as well. | The requirements of the common section apply here as well. | |||

skipping to change at page 19, line 16 | skipping to change at page 19, line 25 | |||

physical route, then a single catastrophic event like a fire in a | physical route, then a single catastrophic event like a fire in a | |||

tunnel could cause an outage or congestion on remaining paths in | tunnel could cause an outage or congestion on remaining paths in | |||

multiple networks. Here it is important to ensure that measurements | multiple networks. Here it is important to ensure that measurements | |||

before the event and after the event are not combined to estimate the | before the event and after the event are not combined to estimate the | |||

composite performance. | composite performance. | |||

Or, when traffic volumes rise due to the rapid spread of an email- | Or, when traffic volumes rise due to the rapid spread of an email- | |||

born worm, loss due to queue overflow in one network may help another | born worm, loss due to queue overflow in one network may help another | |||

network to carry its traffic without loss. | network to carry its traffic without loss. | |||

others... | ||||

6.1.10. Application of Measurement Methodology | 6.1.10. Application of Measurement Methodology | |||

See the common section. | See the common section. | |||

7. Delay Variation Metrics and Statistics | 7. Delay Variation Metrics and Statistics | |||

7.1. Name: Type-P-One-way-pdv-refmin-Poisson/Periodic-Stream | 7.1. Name: Type-P-One-way-pdv-refmin-Poisson/Periodic-Stream | |||

This packet delay variation (PDV) metric is a necessary element of | This packet delay variation (PDV) metric is a necessary element of | |||

Composed Delay Variation metrics, and its definition does not | Composed Delay Variation metrics, and its definition does not | |||

skipping to change at page 19, line 44 | skipping to change at page 19, line 51 | |||

o TstampSrc[i], the wire time of packet[i] as measured at MP(Src) | o TstampSrc[i], the wire time of packet[i] as measured at MP(Src) | |||

(measurement point at the source) | (measurement point at the source) | |||

o TstampDst[i], the wire time of packet[i] as measured at MP(Dst), | o TstampDst[i], the wire time of packet[i] as measured at MP(Dst), | |||

assigned to packets that arrive within a "reasonable" time. | assigned to packets that arrive within a "reasonable" time. | |||

o B, a packet length in bits | o B, a packet length in bits | |||

o F, a selection function unambiguously defining the packets from | o F, a selection function unambiguously defining the packets from | |||

the stream that are selected for the packet-pair computation of | the stream that are selected for the packet-pair computation of | |||

this metric. F(first packet), the first packet of the pair, MUST | this metric. F(current packet), the first packet of the pair, | |||

have a valid Type-P-Finite-One-way-Delay less than Tmax (in other | MUST have a valid Type-P-Finite-One-way-Delay less than Tmax (in | |||

words, excluding packets which have undefined one-way delay) and | other words, excluding packets which have undefined one-way delay) | |||

MUST have been transmitted during the interval T, Tf. The second | and MUST have been transmitted during the interval T, Tf. The | |||

packet in the pair, F(second packet) MUST be the packet with the | second packet in the pair, F(min_delay packet) MUST be the packet | |||

minimum valid value of Type-P-Finite-One-way-Delay for the stream, | with the minimum valid value of Type-P-Finite-One-way-Delay for | |||

in addition to the criteria for F(first packet). If multiple | the stream, in addition to the criteria for F(current packet). If | |||

packets have equal minimum Type-P-Finite-One-way-Delay values, | multiple packets have equal minimum Type-P-Finite-One-way-Delay | |||

then the value for the earliest arriving packet SHOULD be used. | values, then the value for the earliest arriving packet SHOULD be | |||

used. | ||||

o MinDelay, the Type-P-Finite-One-way-Delay value for F(second | o MinDelay, the Type-P-Finite-One-way-Delay value for F(min_delay | |||

packet) given above. | packet) given above. | |||

o N, the number of packets received at the Destination meeting the | o N, the number of packets received at the Destination meeting the | |||

F(first packet) criteria. | F(current packet) criteria. | |||

7.1.2. Definition and Metric Units | 7.1.2. Definition and Metric Units | |||

Using the definition above in section 5.1.2, we obtain the value of | Using the definition above in section 5.1.2, we obtain the value of | |||

Type-P-Finite-One-way-Delay-Poisson/Periodic-Stream[n], the singleton | Type-P-Finite-One-way-Delay-Poisson/Periodic-Stream[n], the singleton | |||

for each packet[i] in the stream (a.k.a. FiniteDelay[i]). | for each packet[i] in the stream (a.k.a. FiniteDelay[i]). | |||

For each packet[n] that meets the F(first packet) criteria given | For each packet[n] that meets the F(first packet) criteria given | |||

above: Type-P-One-way-pdv-refmin-Poisson/Periodic-Stream[n] = | above: Type-P-One-way-pdv-refmin-Poisson/Periodic-Stream[n] = | |||

skipping to change at page 21, line 40 | skipping to change at page 21, line 40 | |||

\ / \ | \ / \ | |||

> | PDV[n]- MeanPDV | | > | PDV[n]- MeanPDV | | |||

/ \ / | / \ / | |||

--- | --- | |||

n = 1 | n = 1 | |||

----------------------------------- | ----------------------------------- | |||

/ \ | / \ | |||

| ( 3/2 ) | | | ( 3/2 ) | | |||

\ (N - 1) * VarPDV / | \ (N - 1) * VarPDV / | |||

We define the Quantile of the IPDVRefMin sample as the value where | We define the Quantile of the PDVRefMin sample as the value where the | |||

the specified fraction of singletons is less than the given value. | specified fraction of singletons is less than the given value. | |||

7.1.5. Composition Functions: | 7.1.5. Composition Functions: | |||

This section gives two alternative composition functions. The | This section gives two alternative composition functions. The | |||

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 | |||

skipping to change at page 24, line 36 | skipping to change at page 24, line 36 | |||

Metrics defined in this memo will be registered in the IANA IPPM | Metrics defined in this memo will be registered in the IANA IPPM | |||

METRICS REGISTRY as described in initial version of the registry | METRICS REGISTRY as described in initial version of the registry | |||

[RFC4148]. | [RFC4148]. | |||

10. Acknowlegements | 10. Acknowlegements | |||

A long time ago, in a galaxy far, far away (Minneapolis), Will Leland | A long time ago, in a galaxy far, far away (Minneapolis), Will Leland | |||

suggested the simple and elegant Type-P-Finite-One-way-Delay concept. | suggested the simple and elegant Type-P-Finite-One-way-Delay concept. | |||

Thanks Will. | Thanks Will. | |||

Yaakov Stein and Donald McLachlan also provided useful comments along | ||||

the way. | ||||

11. Issues (Open and Closed) | 11. Issues (Open and Closed) | |||

This section to be removed at publication. | ||||

>>>>>>>>>>>>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 | 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. | 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 32 | skipping to change at page 26, line 38 | |||

[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. | |||

[RFC2680] Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way | [RFC2680] Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way | |||

Packet Loss Metric for IPPM", RFC 2680, September 1999. | Packet Loss Metric for IPPM", RFC 2680, September 1999. | |||

[RFC3393] Demichelis, C. and P. Chimento, "IP Packet Delay Variation | [RFC3393] Demichelis, C. and P. Chimento, "IP Packet Delay Variation | |||

Metric for IP Performance Metrics (IPPM)", RFC 3393, | Metric for IP Performance Metrics (IPPM)", RFC 3393, | |||

November 2002. | 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 | [RFC4148] Stephan, E., "IP Performance Metrics (IPPM) Metrics | |||

Registry", BCP 108, RFC 4148, August 2005. | Registry", BCP 108, RFC 4148, August 2005. | |||

[RFC5474] Duffield, N., Chiou, D., Claise, B., Greenberg, A., | ||||

Grossglauser, M., and J. Rexford, "A Framework for Packet | ||||

Selection and Reporting", RFC 5474, March 2009. | ||||

[RFC5835] Morton, A. and S. Van den Berghe, "Framework for Metric | [RFC5835] Morton, A. and S. Van den Berghe, "Framework for Metric | |||

Composition", RFC 5835, April 2010. | Composition", RFC 5835, April 2010. | |||

13.2. Informative References | 13.2. Informative References | |||

[RFC5644] Stephan, E., Liang, L., and A. Morton, "IP Performance | [RFC5644] Stephan, E., Liang, L., and A. Morton, "IP Performance | |||

Metrics (IPPM): Spatial and Multicast", RFC 5644, | Metrics (IPPM): Spatial and Multicast", RFC 5644, | |||

October 2009. | October 2009. | |||

[Stats] McGraw-Hill NY NY, "Introduction to the Theory of | [Stats] McGraw-Hill NY NY, "Introduction to the Theory of | |||

End of changes. 34 change blocks. | ||||

53 lines changed or deleted | | 78 lines changed or added | ||

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