IANA Registration of the 'image' Media Type for the Session Description Protocol (SDP)
RFC 6466

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Internet Engineering Task Force (IETF)                      G. Salgueiro
Request for Comments: 6466                                 Cisco Systems
Category: Standards Track                                  December 2011
ISSN: 2070-1721

              IANA Registration of the 'image' Media Type
               for the Session Description Protocol (SDP)

Abstract

   This document describes the usage of the 'image' media type and
   registers it with IANA as a top-level media type for the Session
   Description Protocol (SDP).  This media type is primarily used by SDP
   to negotiate and establish T.38 media streams.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6466.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Salgueiro                    Standards Track                    [Page 1]
RFC 6466             'image' Media Type Registration       December 2011

Table of Contents

   1.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
   2.  Conventions Used in This Document . . . . . . . . . . . . . . . 3
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 3
   4.  Security Considerations . . . . . . . . . . . . . . . . . . . . 4
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 4
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 5
     6.1.  Normative References  . . . . . . . . . . . . . . . . . . . 5
     6.2.  Informative References  . . . . . . . . . . . . . . . . . . 5

1.  Overview

   In an earlier version of the SDP specification [RFC2327] of
   packetized media types, such as those used with the Real-time
   Transport Protocol (RTP) [RFC3550], share the namespace with
   Multipurpose Internet Mail Extensions (MIME) media types registry
   [RFC4288] [RFC4289] (i.e., "MIME media types").  This is in contrast
   to the latest version of the SDP specification [RFC4566], which
   requested that an SDP-specific media type registry be created and
   maintained by IANA.  The top-level SDP media content types registered
   by RFC 4566 [RFC4566] are 'audio', 'video', 'text', 'application',
   and 'message'.  A glaring omission from this list is the 'image'
   media type.

   The 'image' media type is an existing top-level MIME media type and
   is widely used in SDP implementations for setting up T.38 Real-Time
   Facsimile [T38] media streams.  This media type is extensively
   referenced by examples in ITU-T T.38 [T38] and IETF Standards Track
   documents like RFC 4145 [RFC4145].  The following example shows the
   media description of a T.38 media stream as commonly found in a
   Session Initiation Protocol (SIP) [RFC3261] INVITE; it contains an
   SDP offer for T.38 over both UDP Transport Layer (UDPTL) and TCP.
   For the sake of brevity, only the SDP body of the SIP INVITE request
   is displayed in this example.

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RFC 6466             'image' Media Type Registration       December 2011

       v=0
       o=alice 53655765 2353687637 IN IP4 pc33.example.com
       s=SDP image example
       c=IN IP4 192.0.2.2
       t=0 0
       m=image 49170 udptl t38
       a=T38FaxVersion:0
       a=T38MaxBitRate:14400
       a=T38FaxRateManagement:transferredTCF
       a=T38FaxMaxBuffer:262
       a=T38FaxMaxDatagram:90
       a=T38FaxUdpEC:t38UDPRedundancy
       a=sendrecv
       m=image 49172 tcp t38
       a=T38FaxRateManagement:localTCF

   The purpose of this document is to register with IANA the 'image'
   media type as a top-level SDP media type.  This ensures seamless
   continuity with documentation that uses the 'image' MIME media type
   and the previously registered MIME media sub-types like 'image/t38'
   [RFC3362] that are used as SDP media descriptors for T.38 [T38].