RFC 1633 (rfc1633) - Page 2 of 33

Integrated Services in the Internet Architecture: an Overview

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
   overload, while allowing "unused" bandwidth to be available at other
   times.  These classes may represent different user groups or
   different protocol families, for example.  Such a management facility
   is commonly called controlled link-sharing.  We use the term
   integrated services (IS) for an Internet service model that includes
   best-effort service, real-time service, and controlled link sharing.

   The requirements and mechanisms for integrated services have been the
   subjects of much discussion and research over the past several years



Braden, Clark & Shenker