RFC 2598 (rfc2598) - Page 1 of 11


An Expedited Forwarding PHB



Alternative Format: Original Text Document



Network Working Group                                        V. Jacobson
Request for Comments: 2598                                    K. Nichols
Category: Standards Track                                  Cisco Systems
                                                               K. Poduri
                                                            Bay Networks
                                                               June 1999


                      An Expedited Forwarding PHB

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

   The definition of PHBs (per-hop forwarding behaviors) is a critical
   part of the work of the Diffserv Working Group.  This document
   describes a PHB called Expedited Forwarding. We show the generality
   of this PHB by noting that it can be produced by more than one
   mechanism and give an example of its use to produce at least one
   service, a Virtual Leased Line.  A recommended codepoint for this PHB
   is given.

   A pdf version of this document is available at
   ftp://ftp.ee.lbl.gov/papers/ef_phb.pdf

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 [RFC 2474,
   RFC 2475].  This memo describes a particular PHB called expedited
   forwarding (EF). The EF PHB can be used to build a low loss, low
   latency, low jitter, assured bandwidth, end-to-end service through DS
   domains.  Such a service appears to the endpoints like a point-to-
   point connection or a "virtual leased line".  This service has also
   been described as Premium service [2BIT].





Jacobson, et al.            Standards Track