An Expedited Forwarding PHB (Per-Hop Behavior)
RFC 3246
| Document | Type |
RFC - Proposed Standard
(March 2002; No errata)
Obsoletes RFC 2598
|
|
|---|---|---|---|
| Last updated | 2013-03-02 | ||
| Stream | IETF | ||
| Formats | plain text pdf html 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
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