RFC 2597 (rfc2597) - Page 1 of 11
Assured Forwarding PHB Group
Alternative Format: Original Text Document
Network Working Group J. Heinanen
Request for Comments: 2597 Telia Finland
Category: Standards Track F. Baker
Cisco Systems
W. Weiss
Lucent Technologies
J. Wroclawski
MIT LCS
June 1999
Assured Forwarding PHB Group
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 (1999). All Rights Reserved.
Abstract
This document defines a general use Differentiated Services (DS)
[Blake] Per-Hop-Behavior (PHB) Group called Assured Forwarding (AF).
The AF PHB group provides delivery of IP packets in four
independently forwarded AF classes. Within each AF class, an IP
packet can be assigned one of three different levels of drop
precedence. A DS node does not reorder IP packets of the same
microflow if they belong to the same AF class.
1. Purpose and Overview
There is a demand to provide assured forwarding of IP packets over
the Internet. In a typical application, a company uses the Internet
to interconnect its geographically distributed sites and wants an
assurance that IP packets within this intranet are forwarded with
high probability as long as the aggregate traffic from each site does
not exceed the subscribed information rate (profile). It is
desirable that a site may exceed the subscribed profile with the
understanding that the excess traffic is not delivered with as high
probability as the traffic that is within the profile. It is also
Heinanen Standards Track