Re: [MMUSIC] Questions about ICE candidates with BUNDLE - suggested text

[Christer Holmberg <[e-mail]>]

Hi Roman,

My intention was to replace “ICE candidates” with “SDP ‘candidate’ attributes” when related to m= lines. Seems like I forgot about it once I got past the General section… :)

Regards,

Christer

From: Roman Shpount [mailto:[e-mail]]
Sent: 22 February 2016 21:29
To: Christer Holmberg <[e-mail]>
Cc: [e-mail]; Paul Kyzivat <[e-mail]>; Peter Thatcher <[e-mail]>; Ari Keränen <[e-mail]>
Subject: Re: [MMUSIC] Questions about ICE candidates with BUNDLE - suggested text

On Mon, Feb 22, 2016 at 5:10 AM, Christer Holmberg <[e-mail]<mailto:[e-mail]>> wrote:
Assuming we will only associated ICE candidates to the “m=” line associated with the offerer/answerer BUNDLE-tag, below is a first suggested of modified ‘ICE Considerations’ text:

-----------------------

11.  ICE Considerations

11.1.  General

   This section describes how to use the BUNDLE grouping extension
   together with the Interactive Connectivity Establishment (ICE)
   mechanism [RFC5245].

   The generic procedures for negotiating usage of ICE using SDP,
   defined in [I-D.ietf-mmusic-ice-sip-sdp], also apply to usage of ICE
   with BUNDLE, with the following exceptions:

   o  When BUNDLE addresses for a BUNDLE group have been selected for
      both endpoints, ICE connectivity checks and keep-alives only need
      to be performed for the whole BUNDLE group, instead of per bundled
      "m=" line.

   o  Among bundled "m=" lines with which the offerer has associated a
      shared address, the offerer only associates ICE-related media-
      level SDP attributes with the "m=" line associated with the
      offerer BUNDLE-tag.

   o  Among bundled "m=" lines with which the answerer has associated a
      shared address, the answerer only associates ICE-related media-
      level SDP attributes with the "m=" line associated with the
      answerer BUNDLE-tag.

   Support and usage of ICE mechanism together with the BUNDLE extension
   is OPTIONAL.

11.2.  SDP Offer/Answer Procedures

11.2.1.  General

   When an offerer associates a unique address with a bundled "m=" line
   (excluding any bundle-only "m=" line), it MUST also associate unique
   ICE candidates to the "m=" line, according to the procedures in
   [I-D.ietf-mmusic-ice-sip-sdp].

   An offerer MUST NOT associate ICE candidates with a bundle-only "m="
   line with a zero port value.

   NOTE: The bundle-only "m=" line, if accepted by the answerer, will
   inherit the candidates associated with the selected offerer BUNDLE
   address.  An answerer that does not support BUNDLE would not accept a
   bundle-only "m=" line.

   When an offerer or answerer associates a shared address (i.e. a
   previously selected BUNDLE address) with one or more bundled "m="
   lines, the offerer (or answerer) MUST only associate SDP 'candidate'
   attributes with the "m=" line associated with the offerer BUNDLE-tag
   (or the answerer BUNDLE-tag) address).  The offerer or answerer MUST
   NOT associate 'candidiate' attributes with any other bundled "m="
   line to which the offerer (or answerer) associates a shared address.
   This also apply to any other ICE-related media-level SDP attribute.

   NOTE: The following ICE-related media-level SDP attributes are
   defined in [I-D.ietf-mmusic-ice-sip-sdp]: 'candidiate', 'remote-
   candidates', 'ice-mismatch', 'ice-ufrag', 'ice-pwd', and 'ice-
   pacing'.

11.2.2.  Generating the Initial SDP Offer

   When an offerer generates an initial offer, it associates unique ICE
   candidates with the bundled "m=" lines, according to Section 11.2.1.

11.2.3.  Generating the SDP Answer

   When an answerer generates an answer that contains a BUNDLE group,
   the answerer MUST only associate SDP 'candidate' attributes (and
   other ICE-related media-level SDP attributes) with the "m=" line
   associated with the answerer BUNDLE-tag.

11.2.4.  Offerer Processing of the SDP Answer

   When an offerer receives an answer, if the answerer supports and uses
   the ICE mechanism and the BUNDLE extension, the offerer MUST
   associate the same ICE candidates, associated with the "m=" line
   representing the offerer BUNDLE address (selected by the answerer),
   with each bundled "m=" line.

11.2.5.  Modifying the Session

   When an offerer generates a subsequent offer, it associates unique or
   shared ICE candidates with the bundled "m=" lines, according to
   (Section 11.2.1).


I am not 100% sure about what exactly is meant by ICE candidate being associated with an m= line. Does this mean ICE candidate is created for this m= line and "candidate" SDP attribute is included in this m= line?

Overall the text is good, but I would explicitly replace "ICE candidates" with "ICE candidates or any other ICE-related media-level SDP attributes" to avoid any potential confusion. This will also make the phrase "This also apply to any other ICE-related media-level SDP attribute" unnecessary.
_____________
Roman Shpount