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Thank you for the comments Ingemar. As Jean-Francois noted, we have
been through this issue many times before and the solution specified in
the draft reflects WG consensus, which you also supported in the past
(after admittedly considerable discussion). I think it's worth taking a
step back again, and look at what it is you actually want to do here,
and how we can address it. Quoting from an earlier exchange on this
subject ("SDPCapNeg, modified m-line issue", 5/21/2008 on the MMUSIC
list): <quote> Taking a step back, I believe the essence of your comments are, that if we want to use SDP Capability Negotiation to establish media streams, then we cannot do that in a single offer/answer exchange. Instead, you want to have a mechanism whereby we first exchange capabilities between the offerer and the answerer (without establishing a stream) followed by another exchange where we actually negotiate the media stream parameters. In other words, the current single-roundtrip O/A exchange provided by RFC 3264 and supported by SDPCapNeg is replaced by a two-roundtrip solution. <snip> Note however, that the SDPCapNeg framework as currently defined can be used more or less the way you seem to prefer by merely including capabilities in the offer without the actual potential configuration attributes (which are used to trigger the extended O/A exchange). The thing that would be missing is expressing valid combinations of capabilites as well as preferences, however this is part of what the media capabilities extension document is addressing by introducing the "latent configuration" attribute, which you could then use. </quote> In lieu of all the discussion and WG consensus on the currently specified mechanism, can you please explain why the above cannot be used to address your concerns, i.e. either just send capabilities initially, or define an extension that provides the exact semantics you are looking for ? Thanks -- Flemming Ingemar Johansson S wrote: Hi I believe the threads below pretty much summarizes the previous discussions around this topic. The difference is that the new effort is to introduce an extra indicator that essentially says that the 1st offer/answer is only capability exhange in the sense that if "a=spdcapneg-acfg-indication-only" (or something with the same meaning) is present at the session level of the offer SDP, then the answerer MUST only specify actual configuration on the a=acfg line. As mentioned before the proposed change is minimal and as far as I can see it does not break the framework. The indicator is not mandatory to use other than that it may be specified as mandatory in another standards text that use the SDP Capability Negotiation Framework (for instance a 3GPP specification). /Ingemar-----Original Message----- From: Jean-Francois Mule [mailto:jf.mule at cablelabs.com] Sent: den 7 oktober 2008 23:08 To: Ingemar Johansson S; Christer Holmberg Cc: Flemming Andreasen; mmusic at ietf.org Subject: RE: [MMUSIC] Last Call:draft-ietf-mmusic-sdp-capability-negotiation (SDP CapabilityNegotiation) to Proposed Standard (Removing ietf at ietf.org to discuss your Last Call comment on the mmusic list.) Ingemar, Christer, Thank you for the comment. I would like to note the following history related to your IETF Last Call comment: - On June 17, 2008, an email thread "Closing on the SDPCapNeg modified m-line issue" was initiated: http://www.ietf.org/mail-archive/web/mmusic/current/msg06939.html It was addressed to Flemming, Ingemar and Christer explicitly, copied to the list. - Between June 17 and July 7, 3 folks responded to the thread in favor of moving forward (including Ingemar), and there were not one email asking to reopen or address the issue: http://www.ietf.org/mail-archive/web/mmusic/current/msg06940.html http://www.ietf.org/mail-archive/web/mmusic/current/msg06941.html http://www.ietf.org/mail-archive/web/mmusic/current/msg07002.html - at IETF#72, on 8/1, Joerg and I put up the WG status slides (http://www.ietf.org/proceedings/08jul/slides/mmusic-8.pdf, page 5) showing SDP capneg as intended for publication request as soon as draft 09 was out. Both of you were at the meeting and commented on other draft discussions. - On 8/29, the mmusic WG meeting minutes were posted and announced to the list. The minutes (http://www.ietf.org/proceedings/08jul/minutes/mmusic.html) show the ID is awaiting publication request. Just to make sure I get the facts right, was there any new email on this that I missed? If so, please resend. Thank you Jean-Francois. MMUSIC co-chair-----Original Message----- From: mmusic-bounces at ietf.org [mailto:mmusic-bounces at ietf.org] On Behalf Of Ingemar Johansson S Sent: Tuesday, October 07, 2008 6:38 AM To: ietf at ietf.org Cc: Flemming Andreasen; mmusic at ietf.org; Christer Holmberg Subject: Re: [MMUSIC] Last Call:draft-ietf-mmusic-sdp-capability- negotiation (SDP CapabilityNegotiation) to Proposed Standard Hi In draft-ietf-mmusic-sdp-capability-negotiation it is proposed that the transport in the m-line is modified in the SDP answer. |
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