Re: [rtcweb] Agenda requests for Atlanta meeting

"Richard Shockey" <> Tue, 09 October 2012 16:19 UTC

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From: Richard Shockey <>
To: 'Cullen Jennings' <>, 'Roman Shpount' <>
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Date: Tue, 09 Oct 2012 12:18:55 -0400
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Subject: Re: [rtcweb] Agenda requests for Atlanta meeting
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+1 to that idea.

Richard Shockey
Shockey Consulting
Chairman of the Board of Directors SIP Forum
skype-linkedin-facebook: rshockey101

-----Original Message-----
From: [] On Behalf Of
Cullen Jennings
Sent: Monday, October 08, 2012 8:48 PM
To: Roman Shpount
Subject: Re: [rtcweb] Agenda requests for Atlanta meeting

One other thought on this. I think this just points out that it would be
really nice to have a draft that showed how to build a RTCWeb / SIP gateway.

On Oct 8, 2012, at 17:42 , Cullen Jennings <> wrote:

> Check out text from RFC 3311 that says 
>      o  If the UPDATE is being sent before the completion of the INVITE
>         transaction, and the initial INVITE contained an offer, the
>         UPDATE cannot be sent with an offer unless the callee has
>         generated an answer in a reliable provisional response, has
>         received a PRACK for that reliable provisional response, has
>         not received any requests (PRACK or UPDATE) with offers that it
>         has not answered, and has not sent any UPDATE requests
>         containing offers that have not been answered.
> So the 183 would be need to be sent reliably at which case I would expect
the gateways to map it to a final offer in RTCWeb not a provisional one. At
that point when the update comes along with an offer, it just mapped to
RTCweb offer. 
> On Oct 8, 2012, at 16:21 , Roman Shpount <>
> wrote:
>> The scenario is:
>> WebRTC is placing a call through some sort of gateway to a SIP end point.
It sends an offer that gets translated into INVITE with SDP. SIP end point
sends back 183 with SDP that gets delivered to the WebRTC end point as
PRANSWER. Then SIP end point sends an UPDATE with SDP in early dialog. And
then finally SIP end point sends 200 OK with different SDP. I am not sure
how to translate the SDP in UPDATE and the final answer in WebRTC API calls.
I would guess this is not something that can be supported without cloning.
>> _____________
>> Roman Shpount
>> On Mon, Oct 8, 2012 at 7:09 PM, Cullen Jennings <> wrote:
>> Walk me through what the call flow would like it both endpoints were SIP
UA's so I understand it better.
>> Note - I'm not against folks trying to figure out clone. I'm saying that
we should not get rid of PRANSWER.
>> On Oct 8, 2012, at 15:58 , Roman Shpount <> wrote:
>>> Cullen,
>>> I have an existing interop problem with SIP serial forking that I cannot
solve with the proposed schema. With PRANSWER, how would I handle SIP UPDATE
sith SDP received in early dialog?
>>> Regards,
>>> _____________
>>> Roman Shpount
>>> On Mon, Oct 8, 2012 at 6:53 PM, Cullen Jennings (fluffy)
<> wrote:
>>> On Oct 8, 2012, at 2:47 , Christer Holmberg
<> wrote:
>>>> Hi,
>>>> I would like to discuss the different alternatives in order to support
forking, e.g. whether we use cloning, whether we simply set additional local
descriptor, and whether we can get rid of PRANSWER.
>>> Seriously? we have discussed this so many times and always come to the
same conclusion. I have not seen anything on the list that suggests why we
need to remove this or how mapping to SIP 180 with sequential forking is
going to work without it. It also has other important uses. There are a
bunch of changes that are needed to the JSEP draft to remove some of the
inconsistencies in this and clarify some parts but I'd rather wait till we
had that updated before we got into a whole discussion about exploding it
yet again.
>>> Why don't we have a phone call to try and outline what the problems you
are trying to solve that the current solution does not work for then figure
out how much we want to explode this.
>>> I'll note that current clone text has lots of "miracles happen here,
insert supper fluffy hand wave" in it and plenty of weasel room on failure
to allocate required resources on the clone. It's more or less a sketch of
an idea at this point. I'm perfectly happy to see people try and sort out
the details on clone but using it explode the consensus we have come to
around PRANSWER seems like a really bad idea at this point.
>>> Cullen
>>> _______________________________________________
>>> rtcweb mailing list
>>> _______________________________________________
>>> rtcweb mailing list

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