Integrated Services in the Internet Architecture: an Overview
RFC 1633

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Network Working Group                                          R. Braden
Request for Comments: 1633                                           ISI
Category: Informational                                         D. Clark
                                                                     MIT
                                                              S. Shenker
                                                              Xerox PARC
                                                               June 1994

     Integrated Services in the Internet Architecture: an Overview

Status of this Memo

   This memo provides information for the Internet community.  This memo
   does not specify an Internet standard of any kind.  Distribution of
   this memo is unlimited.

Abstract

   This memo discusses a proposed extension to the Internet architecture
   and protocols to provide integrated services, i.e., to support real-
   time as well as the current non-real-time service of IP.  This
   extension is necessary to meet the growing need for real-time service
   for a variety of new applications, including teleconferencing, remote
   seminars, telescience, and distributed simulation.

   This memo represents the direct product of recent work by Dave Clark,
   Scott Shenker, Lixia Zhang, Deborah Estrin, Sugih Jamin, John
   Wroclawski, Shai Herzog, and Bob Braden, and indirectly draws upon
   the work of many others.

Table of Contents

   1. Introduction ...................................................2
   2. Elements of the Architecture ...................................3
      2.1 Integrated Services Model ..................................3
      2.2 Reference Implementation Framework .........................6
   3. Integrated Services Model ......................................11
      3.1 Quality of Service Requirements ............................12
      3.2 Resource-Sharing Requirements and Service Models ...........16
      3.3 Packet Dropping ............................................18
      3.4 Usage Feedback .............................................19
      3.5 Reservation Model ..........................................19
   4. Traffic Control Mechanisms .....................................20
      4.1 Basic Functions ............................................20
      4.2 Applying the Mechanisms ....................................23
      4.3 An example .................................................24
   5. Reservation Setup Protocol .....................................25

Braden, Clark & Shenker                                         [Page 1]
RFC 1633            Integrated Services Architecture           June 1994

      5.1 RSVP Overview ..............................................25
      5.2 Routing and Reservations ...................................28
   6. Acknowledgments ................................................30
   References ........................................................31
   Security Considerations ...........................................32
   Authors' Addresses ................................................33

1. Introduction

   The multicasts of IETF meetings across the Internet have formed a
   large-scale experiment in sending digitized voice and video through a
   packet-switched infrastructure.  These highly-visible experiments
   have depended upon three enabling technologies.  (1) Many modern
   workstations now come equipped with built-in multimedia hardware,
   including audio codecs and video frame-grabbers, and the necessary
   video gear is now inexpensive.  (2) IP multicasting, which is not yet
   generally available in commercial routers, is being provided by the
   MBONE, a temporary "multicast backbone".  (3) Highly-sophisticated
   digital audio and video applications have been developed.

   These experiments also showed that an important technical element is
   still missing: real-time applications often do not work well across
   the Internet because of variable queueing delays and congestion
   losses.  The Internet, as originally conceived, offers only a very
   simple quality of service (QoS), point-to-point best-effort data
   delivery.  Before real-time applications such as remote video,
   multimedia conferencing, visualization, and virtual reality can be
   broadly used, the Internet infrastructure must be modified to support
   real-time QoS, which provides some control over end-to-end packet
   delays.  This extension must be designed from the beginning for
   multicasting; simply generalizing from the unicast (point-to-point)
   case does not work.

   Real-time QoS is not the only issue for a next generation of traffic
   management in the Internet.  Network operators are requesting the
   ability to control the sharing of bandwidth on a particular link
   among different traffic classes.  They want to be able to divide
   traffic into a few administrative classes and assign to each a
   minimum percentage of the link bandwidth under conditions of