Re: [rtcweb] Use of offer / answer semantics

Cullen Jennings <> Wed, 07 September 2011 00:58 UTC

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From: Cullen Jennings <>
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Date: Tue, 06 Sep 2011 18:59:45 -0600
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To: Emil Ivov <>
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Subject: Re: [rtcweb] Use of offer / answer semantics
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On Sep 6, 2011, at 9:49 AM, Emil Ivov wrote:

>> 1) The media negotiations will be done using the same SDP
>> offer/answer semantics that are used in SIP.
> Does this cover media format negotiation only or does it also cover
> transport negotiation? I believe you once mentioned you were a fan of
> "sending ICE candidates as they become available" and for that to happen
> we'd probably need something more XMPP-like than SIP/SDP-like.

The SDP offer / answer cover both and in fact mix them together in a way that is a bit hard to untangle,  so yes, what I am proposing here is that it would cover both. 

In general, I am a fan of the separating the setup of the ICE transport channels from the negotiation of what goes over them but I think we are just too late at this point to really get into doing that and I don't see much support for it. The hard part of this is how to design a signaling GW that does not require a media GW but can map between this and SIP. Thought we might be able to do this, and I think it would be architecturally cleaner, it's a lot more complicated to done. I don't see the work happening to make something like this happen in a time span where it will be relevant. I think people are just looking for something much closer to existing implementations in Chrome and Firefox.