Subject: [Insipid] disaggregated media

From: Brett Tate <[email-masked]>
Date: Fri, 29 Mar 2013 15:10:11 +0000

Hi,

Concerning slides-86-insipid-5.pdf's "Disaggregated Media" slide, I thought that I'd mention that the call flow is a variant of the one that I originally sent.  I mention it mainly because the variant appears more like a conference since it relays media and doesn't accommodate end-to-end ACK; although, I'm not sure if that'd change anyone's opinion on the topic.

http://www.ietf.org/mail-archive/web/insipid/current/msg00429.html

Since there was some debate concerning if Session-ID values should be more like the slide or the above email, I thought that I'd mention that a common scenario is that INVITE to "Bob's computer" is quickly declined or cancelled after "Bob's phone" answers the INVITE.  That is one of the reasons why the Session-ID values mentioned within the above email might be more appropriate.  However if the Session-ID values of the slide is preferred, should "M" continue to be part of the Session-ID (i.e. instead of switching to be "A" and "Bp") when "Bob's computer" is not part of the answered call?

Thanks,
Brett

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From: James Polk <[email-masked]>
Date: Fri, 29 Mar 2013 12:38:29 -0500

At 10:10 AM 3/29/2013, Brett Tate wrote:
>Hi,
>
>Concerning slides-86-insipid-5.pdf's "Disaggregated Media" slide, I 
>thought that I'd mention that the call flow is a variant of the one 
>that I originally sent.  I mention it mainly because the variant 
>appears more like a conference since it relays media and doesn't 
>accommodate end-to-end ACK; although, I'm not sure if that'd change 
>anyone's opinion on the topic.
>
>Since there was some debate concerning if Session-ID values should 
>be more like the slide or the above email, I thought that I'd 
>mention that a common scenario is that INVITE to "Bob's computer" is 
>quickly declined or cancelled after "Bob's phone" answers the INVITE.

Brett - If this INVITE to Bob's computer is CANCELled (such as in the 
case of concurrent forking), then the SIP state engine for that UA 
would become "inactive" and would no longer be part of any active 
call, therefore wouldn't this defeat the purpose of originally having 
the intent of only the video being sent and displayed on Bob's 
computer? i.e., wouldn't the only active part of the call be from 
Alice to Bob's phone (in audio only mode)?

>That is one of the reasons why the Session-ID values mentioned 
>within the above email might be more appropriate.  However if the 
>Session-ID values of the slide is preferred,

I don't know if the slide was preferred, but I answered your email 
with a diagram on Jan 11th (the final message on the thread) and no 
one said I was wrong, so that's what I built the slide upon.

>should "M" continue to be part of the Session-ID (i.e. instead of 
>switching to be "A" and "Bp") when "Bob's computer" is not part of 
>the answered call?

That was one of the open questions to the room. If a conference call, 
I'd say yes. If not a conference, I'd say you have some special 
handling within the B2BUA that does the SDP splitting and some in the 
room wanted no special handling rules regardless the entity type - 
something I wasn't a fan of, BTW. I just believe one needs to clearly 
describe the scenario so everyone codes every entity the same way for 
every special case. I agree with limiting the number of special 
cases, but we're burying our heads in the sand if we think we can 
contain vendors from doing special one-offs, and customers from 
asking for one-offs. If we hope to be successful as a WG, we need to 
address the obvious one-offs in a uniform way IMO. That does NOT mean 
every one-off, just limited set of obvious ones.

James

>Thanks,
>Brett
>
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>is addressed and may contain confidential and/or privileged 
>information. If you are not the intended recipient and have received 
>this email in error, please notify BroadSoft, Inc. immediately by 
>replying to this message, and destroy all copies of this message, 
>along with any attachment, prior to reading, distributing or copying it.
>_______________________________________________
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---

From: Brett Tate <[email-masked]>
Date: Fri, 29 Mar 2013 20:22:50 +0000

Thanks for the response.  Reply is inline.

> computer? 

The service allows the called party (Bob) to decide to answer audio only (i.e. phone) or both audio/video (i.e. phone and computer).

> i.e., wouldn't the only active part of the call be from

Yes; since Bob decided not to answer video.

> one said I was wrong, so that's what I built the slide upon.

My impression from the 1/15 email was that the authors and working group were still thinking about it.

http://www.ietf.org/mail-archive/web/insipid/current/msg00457.html 

The slide doesn't appear to indicate your reply (at least the snippet shown below); however the slide does reflect the response from Paul Jones and Paul Kyzivat.  I currently don't have a strong preference.

"However,
 - from the B2BUA to Bob's phone, the Session-ID should be (A,Bp)
and
 - from the B2BUA to Bob's computer, the Session-ID should be (A,Bc)"