RFC 1453 (rfc1453) - Page 1 of 10

A Comment on Packet Video Remote Conferencing and the Transport/Network Layers

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Network Working Group                                        W. Chimiak
Request for Comments: 1453                                         BGSM
                                                             April 1993


         A Comment on Packet Video Remote Conferencing and the
                        Transport/Network Layers

Status of this Memo

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

Abstract

   The new generation of multimedia applications demands new features
   and new mechanisms for proper performance.  ATM technology has moved
   from concept to reality, delivering very high bandwidths and new
   capabilities to the data link layer user.  In an effort to anticipate
   the high bandwidth-delay data link layer, Delta-t [Delta-t], NETBLT
   [RFC 988], and VMTP [RFC 1045] were developed.  The excellent
   insights and mechanisms pioneered by the creators of these
   experimental Internet protocols were used in the design of Xpress
   Transfer Protocol (XTP) [XTP92] with the goal of eventually
   delivering ATM bandwidths to a user process.  This RFC is a vehicle
   to inform the Internet community about XTP as it benefits from past
   Internet activity and targets general-purpose applications and
   multimedia applications with the emerging ATM networks in mind.

1.  Introduction

   Networking is no longer synonymous with analog telephony.  High-
   performance lower-layer networks have made possible exciting new
   applications: collaboratory environments, distributed client/server
   computing, remote conferencing, teleclassrooms, and distributed
   life-sciences imaging.  These applications normally demand a great
   deal of bandwidth and often create operating system bottlenecks.
   Enabling these new multimedia applications entails delivering
   bandwidth to the applications, not just having bandwidth available on
   the network.  This statement may appear obvious, but often solutions
   at the transport layer are satisfied by having bandwidth at that
   layer without sufficient sensitivity to higher-layer access to the
   bandwidth.  The unavailability of bandwidth at upper layers is
   becoming the real issue as the networks are becoming a high-
   performance virtual backplane without concomitant high-performance
   control schemes.  It appears that new services are needed that
   require communication with all layers.  The ATM architecture calls



Chimiak
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