Subject: [clue] CLUE Fallback

From: Christian Groves <[email-masked]>
Date: Tue, 10 Sep 2013 21:04:25 +1000

Hello

I've been having some off-line discussions with Paul K regarding whether 
a CLUE session needs to stay active for an entire session once 
established (barring any failures).

I mentioned a "fallback to audio scenario". E.g. a case where a user is 
participating through a CLUE enabled mobile or PC using video but then 
wants to transition back to audio mode (they don't require or have 
telepresence capabilities) because they want to start moving around or 
they don't want to be part of the video feed anymore.

In this case I think there could be a need for a procedure to allow an 
Advertiser to close a CLUE association but keep the audio from the 
session active. Effectively this is opposite procedure to first 
establishing a "legacy" media session and then upgrading it to a full 
CLUE session.

3GPP has similar type of functionality CS Multimedia drop back to audio 
and a requirement in IMS Multimedia to drop video streams back to audio.

What are people's thoughts?

Regards, Christian

---

From: "Roni Even" <[email-masked]>
Date: Tue, 10 Sep 2013 16:04:31 +0300

Hi Christian,
I think that the more general question is what happens if the CLUE channel
is closed. 
My thinking is that if the SDP still have the media channel open then the
media continues to flow. So for example in a point to point call once a
steady state is achieved is there a reason to keep the CLUE channel open?

In your example the closing of the CLUE channel will be followed by and
RFC3264 offer that will close the video channels.
Roni

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On Behalf Of
> Christian Groves
> Sent: 10 September, 2013 2:04 PM
> To: [email-masked]
> Subject: [clue] CLUE Fallback
> 
> Hello
> 
> I've been having some off-line discussions with Paul K regarding whether a
> CLUE session needs to stay active for an entire session once established
> (barring any failures).
> 
they
> don't want to be part of the video feed anymore.
> 
> Advertiser to close a CLUE association but keep the audio from the session
> active. Effectively this is opposite procedure to first establishing a
"legacy"
> media session and then upgrading it to a full CLUE session.
> 
and a
> requirement in IMS Multimedia to drop video streams back to audio.
> 
> _______________________________________________
> clue mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/clue

---

From: Paul Kyzivat <[email-masked]>
Date: Tue, 10 Sep 2013 09:11:36 -0400

(as individual)

I agree, now that Christian has provided a use case.

I think we need a way to signal a desire to cease CLUE behavior and 
return to legacy mode. At that point the clue channel can be closed.

Conversely, IMO, if the clue channel, or the SCTP association carrying 
it, is closed/dropped after clue mode has been established, then we 
should enter an error recovery mode where we attempt to reestablish the 
clue channel. And while that is going on I think media should continue 
to be processed according to the last successful configuration in each 
direction.

	Thanks,
	Paul