Packet Delay Variation Applicability Statement
RFC 5481
Network Working Group A. Morton
Request for Comments: 5481 AT&T Labs
Category: Informational B. Claise
Cisco Systems, Inc.
March 2009
Packet Delay Variation Applicability Statement
Status of This Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents in effect on the date of
publication of this document (http://trustee.ietf.org/license-info).
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document.
This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
Morton & Claise Informational [Page 1]
RFC 5481 Delay Variation AS March 2009
Abstract
Packet delay variation metrics appear in many different standards
documents. The metric definition in RFC 3393 has considerable
flexibility, and it allows multiple formulations of delay variation
through the specification of different packet selection functions.
Although flexibility provides wide coverage and room for new ideas,
it can make comparisons of independent implementations more
difficult. Two different formulations of delay variation have come
into wide use in the context of active measurements. This memo
examines a range of circumstances for active measurements of delay
variation and their uses, and recommends which of the two forms is
best matched to particular conditions and tasks.
Table of Contents
1. Introduction ....................................................4
1.1. Requirements Language ......................................5
1.2. Background Literature in IPPM and Elsewhere ................5
1.3. Organization of the Memo ...................................6
2. Purpose and Scope ...............................................7
3. Brief Descriptions of Delay Variation Uses ......................7
3.1. Inferring Queue Occupation on a Path .......................7
3.2. Determining De-Jitter Buffer Size ..........................8
3.3. Spatial Composition .......................................10
3.4. Service-Level Comparison ..................................10
3.5. Application-Layer FEC Design ..............................10
4. Formulations of IPDV and PDV ...................................10
4.1. IPDV: Inter-Packet Delay Variation ........................11
4.2. PDV: Packet Delay Variation ...............................11
4.3. A "Point" about Measurement Points ........................12
4.4. Examples and Initial Comparisons ..........................12
5. Survey of Earlier Comparisons ..................................13
5.1. Demichelis' Comparison ....................................13
5.2. Ciavattone et al. .........................................15
5.3. IPPM List Discussion from 2000 ............................16
5.4. Y.1540 Appendix II ........................................18
5.5. Clark's ITU-T SG 12 Contribution ..........................18
6. Additional Properties and Comparisons ..........................18
6.1. Packet Loss ...............................................18
6.2. Path Changes ..............................................19
6.2.1. Lossless Path Change ...............................20
6.2.2. Path Change with Loss ..............................21
6.3. Clock Stability and Error .................................22
6.4. Spatial Composition .......................................24
6.5. Reporting a Single Number (SLA) ...........................24
6.6. Jitter in RTCP Reports ....................................25
Morton & Claise Informational [Page 2]
Show full document text