An Expedited Forwarding PHB (Per-Hop Behavior)
RFC 3246
Document | Type |
RFC - Proposed Standard
(March 2002; No errata)
Obsoletes RFC 2598
|
|
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Authors | William Courtney , Dimitrios Stiliadis , Jon Bennett , Shahram Davari , Jean-Yves Le Boudec , Kent Benson , Victor Firoiu , Bruce Davie , Anna Charny | ||
Last updated | 2013-03-02 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 3246 (Proposed Standard) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group B. Davie Request for Comments: 3246 A. Charny Obsoletes: 2598 Cisco Systems, Inc. Category: Standards Track J.C.R. Bennett Motorola K. Benson Tellabs J.Y. Le Boudec EPFL W. Courtney TRW S. Davari PMC-Sierra V. Firoiu Nortel Networks D. Stiliadis Lucent Technologies March 2002 An Expedited Forwarding PHB (Per-Hop Behavior) Status of this Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (2001). All Rights Reserved. Abstract This document defines a PHB (per-hop behavior) called Expedited Forwarding (EF). The PHB is a basic building block in the Differentiated Services architecture. EF is intended to provide a building block for low delay, low jitter and low loss services by ensuring that the EF aggregate is served at a certain configured rate. This document obsoletes RFC 2598. Davie, et. al. Standards Track [Page 1] RFC 3246 An Expedited Forwarding PHB March 2002 Table of Contents 1 Introduction ........................................... 2 1.1 Relationship to RFC 2598 ............................... 3 2 Definition of EF PHB ................................... 3 2.1 Intuitive Description of EF ............................ 3 2.2 Formal Definition of the EF PHB ........................ 5 2.3 Figures of merit ....................................... 8 2.4 Delay and jitter ....................................... 8 2.5 Loss ................................................... 9 2.6 Microflow misordering .................................. 9 2.7 Recommended codepoint for this PHB ..................... 9 2.8 Mutability ............................................. 10 2.9 Tunneling .............................................. 10 2.10 Interaction with other PHBs ............................ 10 3 Security Considerations ................................ 10 4 IANA Considerations .................................... 11 5 Acknowledgments ........................................ 11 6 References ............................................. 11 Appendix: Implementation Examples .............................. 12 Authors' Addresses ............................................. 14 Full Copyright Statement ....................................... 16 1. Introduction Network nodes that implement the differentiated services enhancements to IP use a codepoint in the IP header to select a per-hop behavior (PHB) as the specific forwarding treatment for that packet [3, 4]. This memo describes a particular PHB called expedited forwarding (EF). The intent of the EF PHB is to provide a building block for low loss, low delay, and low jitter services. The details of exactly how to build such services are outside the scope of this specification. The dominant causes of delay in packet networks are fixed propagation delays (e.g. those arising from speed-of-light delays) on wide area links and queuing delays in switches and routers. Since propagation delays are a fixed property of the topology, delay and jitter are minimized when queuing delays are minimized. In this context, jitter is defined as the variation between maximum and minimum delay. The intent of the EF PHB is to provide a PHB in which suitably marked packets usually encounter short or empty queues. Furthermore, if queues remain short relative to the buffer space available, packetShow full document text