Re: [rtcweb] Use of offer / answer semantics
Paul Kyzivat <pkyzivat@alum.mit.edu> Thu, 08 September 2011 17:11 UTC
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Date: Thu, 08 Sep 2011 13:14:12 -0400
From: Paul Kyzivat <pkyzivat@alum.mit.edu>
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Subject: Re: [rtcweb] Use of offer / answer semantics
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On 9/8/11 12:05 PM, Roman Shpount wrote: > If the goal is to create something that will interop with an existing > SIP infrastructure using a signalling proxy only, we would need is to > fully support RFC 3264. I think what we will need is an ability to > generate an initial offer (as SDP), process the provisional SDP > response, process final SDP response, process an offer and generate the > response, and generate a new offer for the existing call (similar to the > response to the SIP INVITE with no body) in accordance with rules in RFC > 3264. We will need to decide which SDP related RFC would need to be > supported, but I think RFC 4566, RFC 3551, RFC 5245, and RFC 3605 are > the minimum. If I understand you, then I think we are in agreement. Thanks, Paul > _____________ > Roman Shpount > > > On Thu, Sep 8, 2011 at 11:52 AM, Paul Kyzivat <pkyzivat@alum.mit.edu > <mailto:pkyzivat@alum.mit.edu>> wrote: > > On 9/8/11 12:45 AM, Bernard Aboba wrote: > > > > > 1) The media negotiations will be done using the same SDP > offer/answer semantics that are used in SIP. > > To be precise - you're suggesting that we use RFC 3264 > offer/answer > > semantics. (That RFC is 25 pages long. RFC 3261, the core SIP > document, > > is 269 pages, and is NOT a normative reference from 3264. I > am anxious > > to avoid having a normative dependency on 3261.) > > > > I agree with this. > > [BA] I do *not* agree that RTCWEB should have to support every > aspect of > SDP offer/answer. Basic offer/answer, sure. All potential corner > cases? > Not necessarily. > > > I'm not sure where you are going here? > Are you suggesting that all the mandatory to implement O/A semantics > of 3264 might not be supported? Or are you saying that O/A support > may not work for all defined SDP extensions? > > I think that all mandatory O/A should be supported. If you have > something specific in mind that is problematic, then maybe we should > investigate why you think it needs to be excluded. My guess is that > maybe it is something broken in the spec that ought to be fixed there. > > > > > 2) It will be possible to gateway between legacy SIP > devices that > support ICE and appropriate RTP / SDP mechanisms and codecs without > using a media gateway. A signaling gateway to convert between the > signaling on the web side to the SIP signaling may be needed. > > > I agree with this - I think the "may be needed" will turn out > to be > > "will be needed", but some portion of that gateway can be > implemented by > > Javascript running in the browser, if desirable. > > [BA] This seems like a good principle, but I'm not clear that it > will > work with all use cases. For example, what happens in the E911 > use cases > when an RTCWEB implementation attempts to make a call to a PSAP > implementing NENA i3 Stage 3? If you don't have a media gateway, > then > the browser will need to implement one of the mandated codecs on the > PSAP side. So in those use cases, eliminating the media gateway > implies > making G.711 and H.264 mandatory-to-implement. > > > AFAIK, not every rtcweb application will be obligated to support E911. > (In particular, any application that doesn't identify callees by > phone number is a good candidate to be exempt from E911. > > Certainly a server without a media gateway will be limited in what > it can call based on codec compatibility. That may or may not be a > limitation, depending on the application. Those that find it an > unacceptable limitation will probably find a way to incorporate a > transcoder when needed. > > Thanks, > Paul > > _________________________________________________ > rtcweb mailing list > rtcweb@ietf.org <mailto:rtcweb@ietf.org> > https://www.ietf.org/mailman/__listinfo/rtcweb > <https://www.ietf.org/mailman/listinfo/rtcweb> > > > > > _______________________________________________ > rtcweb mailing list > rtcweb@ietf.org > https://www.ietf.org/mailman/listinfo/rtcweb
- [rtcweb] Use of offer / answer semantics Cullen Jennings
- Re: [rtcweb] Use of offer / answer semantics Colin Perkins
- Re: [rtcweb] Use of offer / answer semantics Matthew Kaufman
- Re: [rtcweb] Use of offer / answer semantics Emil Ivov
- Re: [rtcweb] Use of offer / answer semantics Emil Ivov
- Re: [rtcweb] Use of offer / answer semantics Colin Perkins
- Re: [rtcweb] Use of offer / answer semantics Emil Ivov
- Re: [rtcweb] Use of offer / answer semantics Cullen Jennings
- Re: [rtcweb] Use of offer / answer semantics Cullen Jennings
- Re: [rtcweb] Use of offer / answer semantics Cullen Jennings
- Re: [rtcweb] Use of offer / answer semantics Harald Alvestrand
- Re: [rtcweb] Use of offer / answer semantics Henry Sinnreich
- Re: [rtcweb] Use of offer / answer semantics Bernard Aboba
- Re: [rtcweb] Use of offer / answer semantics Tim Panton
- Re: [rtcweb] Use of offer / answer semantics Harald Alvestrand
- Re: [rtcweb] Use of offer / answer semantics Olle E. Johansson
- Re: [rtcweb] Use of offer / answer semantics Roman Shpount
- Re: [rtcweb] Use of offer / answer semantics Paul Kyzivat
- Re: [rtcweb] Use of offer / answer semantics Dzonatas Sol
- Re: [rtcweb] Use of offer / answer semantics Paul Kyzivat
- Re: [rtcweb] Use of offer / answer semantics Hadriel Kaplan
- Re: [rtcweb] Use of offer / answer semantics Olle E. Johansson
- [rtcweb] Supporting legacy PSTN interop (was: Use… Hadriel Kaplan
- Re: [rtcweb] Supporting legacy PSTN interop (was:… Ravindran Parthasarathi
- Re: [rtcweb] Use of offer / answer semantics Randell Jesup
- Re: [rtcweb] Use of offer / answer semantics Hadriel Kaplan