Spatial Composition of Metrics
RFC 6049

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Internet Engineering Task Force (IETF)                         A. Morton
Request for Comments: 6049                                     AT&T Labs
Category: Standards Track                                     E. Stephan
ISSN: 2070-1721                                    France Telecom Orange
                                                            January 2011

                     Spatial Composition of Metrics

Abstract

   This memo utilizes IP performance metrics that are applicable to both
   complete paths and sub-paths, and it defines relationships to compose
   a complete path metric from the sub-path metrics with some accuracy
   with regard to the actual metrics.  This is called "spatial
   composition" in RFC 2330.  The memo refers to the framework for
   metric composition, and provides background and motivation for
   combining metrics to derive others.  The descriptions of several
   composed metrics and statistics follow.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6049.

Morton & Stephan             Standards Track                    [Page 1]
RFC 6049                   Spatial Composition              January 2011

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Morton & Stephan             Standards Track                    [Page 2]
RFC 6049                   Spatial Composition              January 2011

Table of Contents

   1. Introduction ....................................................4
      1.1. Motivation .................................................6
      1.2. Requirements Language ......................................6
   2. Scope and Application ...........................................6
      2.1. Scope of Work ..............................................6
      2.2. Application ................................................7
      2.3. Incomplete Information .....................................7
   3. Common Specifications for Composed Metrics ......................8
      3.1. Name: Type-P ...............................................8
           3.1.1. Metric Parameters ...................................8
           3.1.2. Definition and Metric Units .........................9
           3.1.3. Discussion and Other Details ........................9
           3.1.4. Statistic ...........................................9
           3.1.5. Composition Function ................................9
           3.1.6. Statement of Conjecture and Assumptions ............10
           3.1.7. Justification of the Composition Function ..........10
           3.1.8. Sources of Deviation from the Ground Truth .........10
           3.1.9. Specific Cases where the Conjecture Might Fail .....11
           3.1.10. Application of Measurement Methodology ............12
   4. One-Way Delay Composed Metrics and Statistics ..................12
      4.1. Name: Type-P-Finite-One-way-Delay-<Sample>-Stream .........12
           4.1.1. Metric Parameters ..................................12
           4.1.2. Definition and Metric Units ........................12
           4.1.3. Discussion and Other Details .......................13