Re: [rtcweb] SDP_PRANSWER followed by SDP_OFFER scenario in JSEP

Justin Uberti <juberti@google.com> Thu, 10 May 2012 20:56 UTC

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From: Justin Uberti <juberti@google.com>
Date: Thu, 10 May 2012 16:56:07 -0400
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To: Martin Thomson <martin.thomson@gmail.com>
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Cc: Randell Jesup <randell-ietf@jesup.org>, "rtcweb@ietf.org" <rtcweb@ietf.org>
Subject: Re: [rtcweb] SDP_PRANSWER followed by SDP_OFFER scenario in JSEP
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The other use case is the one Partha originally mentioned, and recently
resurfaced:

Issue 2)  UPDATE support within SIP early dialog in the non-forking
scenario. Here, the cloning will not solve issue as the answerer originated
the new offer during SDP_PRANSWER state . Issue 2 is the title of this mail
thread.

which I think expands to:
1. local PC1 sends offer, forks to remote PC1 and PC2
2. remote PC1 receives offer, sends pranswer
3. local PC1 applies this pranswer
4. remote PC2 receives offer, sends pranswer
5. local PC1 applies this pranswer
6. remote PC1 sends update (i.e. new offer)
7. local PC1 does ???

Richard mentioned that this could be solved by cloning, and I think I agree.
local PC1 can clone at step 5, and create local PC2. local PC2 stays in the
pranswer state; local PC1 applies the previous pranswer as final, and then
handles the new offer (update).


On Thu, May 10, 2012 at 3:53 PM, Martin Thomson <martin.thomson@gmail.com>wrote;wrote:

> On 10 May 2012 12:05, Cullen Jennings <fluffy@iii.ca> wrote:
> > I'm a very confused on what type of forking (with ICE) use case people
> want to satisfy.
>
> Here's the use case as I understand it:
>
> create offer and send to some thing
> the offer actually hits multiple things
> multiple answers arrive
> want to establish sessions with all of them
>
> That's the use case.  Adding it to the use cases draft (or not) is
> probably something that needs to be debated more.
>
> --Martin
>
> p.s. How the offer reaches multiple things doesn't matter much.  I see
> too many emails on these lists that include the letters S, I and P
> together.
> _______________________________________________
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>