T.140 Text Conversation over WebRTC Data Channels
draft-holmberg-mmusic-t140-usage-data-channel-00

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MMUSIC Working Group                                         C. Holmberg
Internet-Draft                                                  Ericsson
Intended status: Standards Track                          August 9, 2019
Expires: February 10, 2020

           T.140 Text Conversation over WebRTC Data Channels
            draft-holmberg-mmusic-t140-usage-data-channel-00

Abstract

   This document specifies how a WebRTC data channel can be used as a
   transport mechanism for the ITU-T Protocol for multimedia application
   text conversation (Recommendation ITU-T T.140), and how the SDP
   offer/answer mechanism can be used to negotiate such data channel,
   referred to as T.140 data channel.

Status of This Memo

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   This Internet-Draft will expire on February 10, 2020.

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   Copyright (c) 2019 IETF Trust and the persons identified as the
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  SDP Considerations  . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Use of dcmap Attribute  . . . . . . . . . . . . . . . . .   3
     3.2.  Use of dcsa Attribute . . . . . . . . . . . . . . . . . .   4
     3.3.  Example . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  T.140 Considerations  . . . . . . . . . . . . . . . . . . . .   5
     4.1.  Session Layer Functions . . . . . . . . . . . . . . . . .   5
     4.2.  Data Encoding and Sending . . . . . . . . . . . . . . . .   5
     4.3.  Data Buffering  . . . . . . . . . . . . . . . . . . . . .   5
   5.  Gateway Considerations  . . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  IANA considerations . . . . . . . . . . . . . . . . . . . . .   6
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   The ITU-T Protocol for multimedia application text conversation
   (Recommendation ITU-T T.140) [T140] defines a protocol for text
   conversation, also known as realtime text or text telephony.  The
   native transport for IP networks is based on the Real-time Transport
   Protocol (RTP) [RFC4103].

   This document specifies how a WebRTC data channel
   [I-D.ietf-rtcweb-data-channel] can be used as a transport mechanism
   for T.140, and how the SDP offer/answer mechanism
   [I-D.ietf-mmusic-data-channel-sdpneg] can be used to negotiate such
   data channel.

   In this document, a T.140 data channel refers to a WebRTC data
   channel for which the instantiated sub-protocol is "t140", and where
   the channel is negotiated using the SDP-based external negotiation
   method [I-D.ietf-mmusic-data-channel-sdpneg].

   NOTE - This WebRTC term of a "T.140 data channel" is actually synonym
   to the originally introduced concept of a "T.140 data channel"] for
   the T.140 protocol back in 1998, see Section 4.3 of [T140].

   NOTE - The decision to transport realtime text over a data channel,
   instead of using RTP based transport [RFC4103], in WebRTC is
   constituted by use-case "U-C 5: Realtime text chat during an audio

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