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

[Christer Holmberg <[e-mail]>]

Hi,

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:

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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).

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

Regards,

Christer


From: mmusic [mailto:[e-mail]] On Behalf Of Christer Holmberg
Sent: 21 February 2016 12:12
To: Roman Shpount <[e-mail]>
Cc: Paul Kyzivat <[e-mail]>; [e-mail]
Subject: Re: [MMUSIC] Questions about ICE candidates with BUNDLE

Hi Roman,

I didn't check whether some of the ICE attributes were session-level, but I agree with what you say: the same rule should apply to all media-level ICE attributes.

Regards,

Christer

Sent from my Windows Phone
________________________________
From: Roman Shpount<mailto:[e-mail]>
Sent: ‎21/‎02/‎2016 08:21
To: Christer Holmberg<mailto:[e-mail]>
Cc: Peter Thatcher<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>; Paul Kyzivat<mailto:[e-mail]>
Subject: Re: [MMUSIC] Questions about ICE candidates with BUNDLE
On Sat, Feb 20, 2016 at 12:57 PM, Christer Holmberg <[e-mail]<mailto:[e-mail]>> wrote:
>> Correct, and that's one reason I suggest that we limit the scope to ICE, eventhough we probably
>> could do the same thing for any IDENTICAL and TRANSPORT category attribute.
>
​> While it would be nice to remove any duplication, the duplication is particularly painful for ICE candidates, because
> there can be a lot of them, and because they change without any offer/answer action (thanks to trickle ICE). ​
> So if we just covered that candidates, we'd be getting most of the value.

Assuming the scope is ICE, shouldn't the same still apply also to other ICE related attributes? I assume the values for the "remote-candidates",  "ice-lite", "ice-mismatch", "ice-ufrag", "ice-pwd", "ice-pacing" and "ice-options" attributes will be identical within a BUNDLE group, so...

"ice-lite" and "ice-options" are session level only candidates, so they should not be in the m= line BUNDLE or any other type. The same logic that applies to ICe candidates should apply to other media level ICE SDP attributes or things will break

Regards,
_____________
Roman Shpount