Re: [MMUSIC] Last Call: <draft-ietf-mmusic-rfc4566bis-34.txt> (SDP: Session Description Protocol) to Proposed Standard

Magnus Westerlund <> Thu, 11 April 2019 08:14 UTC

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From: Magnus Westerlund <>
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CC: Adam Roach <>, "" <>, "" <>, "" <>
Thread-Topic: [MMUSIC] Last Call: <draft-ietf-mmusic-rfc4566bis-34.txt> (SDP: Session Description Protocol) to Proposed Standard
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Subject: Re: [MMUSIC] Last Call: <draft-ietf-mmusic-rfc4566bis-34.txt> (SDP: Session Description Protocol) to Proposed Standard
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MMUSIC WG, Document Editors

In the processing of draft-ietf-mmusic-data-channel-sdpneg-25 an interesting question arose regarding text strings in SDP attribute values.

Currently the document says:

4.5.  Internationalization

   The SDP specification recommends the use of the ISO 10646 character
   set in the UTF-8 encoding [RFC3629] to allow many different languages
   to be represented.  However, to assist in compact representations,
   SDP also allows other character sets such as ISO 8859-1 to be used
   when desired.  Internationalization only applies to free-text sub-
   fields (session name and background information), and not to SDP as a

If one like to include UTF-8 field for attributes it would be good if
the requirement would be clear going forward that there is an expectancy
that at least parser can process any UTF-8 strings that may occur in any

That would allow future SDP field values to use UTF-8 strings without risks
and simplify processing. Like in the case of the data channel SDP mapping
where the extra step of encoding lable characters not visually safe as escaped
characters could be avoided.

Does anyone have input if making such a change would have significant impact on
the interoperability?



On 2019-03-22 15:46, The IESG wrote:

The IESG has received a request from the Multiparty Multimedia Session
Control WG (mmusic) to consider the following document: - 'SDP: Session
Description Protocol'
  <draft-ietf-mmusic-rfc4566bis-34.txt> as Proposed Standard

The IESG plans to make a decision in the next few weeks, and solicits final
comments on this action. Please send substantive comments to the<> mailing lists by 2019-04-12. Exceptionally, comments may be
sent to<> instead. In either case, please retain the beginning of
the Subject line to allow automated sorting.


   This memo defines the Session Description Protocol (SDP).  SDP is
   intended for describing multimedia sessions for the purposes of
   session announcement, session invitation, and other forms of
   multimedia session initiation.  This document obsoletes RFC 4566.

The file can be obtained via

IESG discussion can be tracked via

No IPR declarations have been submitted directly on this I-D.

mmusic mailing list<>


Magnus Westerlund

Network Architecture & Protocols, Ericsson Research
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