Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcweb-signaling - More-coming and final answer (Section 5.2.3)

Christer Holmberg <> Wed, 19 October 2011 13:06 UTC

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From: Christer Holmberg <>
To: Cullen Jennings <>, "" <>
Date: Wed, 19 Oct 2011 15:06:20 +0200
Thread-Topic: [rtcweb] SDP Offer/Answer draft-jennings-rtcweb-signaling - More-coming and final answer (Section 5.2.3)
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Cc: Jonathan Rosenberg <>
Subject: Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcweb-signaling - More-coming and final answer (Section 5.2.3)
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A couple of questions regarding the usage of the more-coming flag:

Q1. If one sends an ANSWER with the more-coming flag set to 'true', is it allowed to later send *additional* ANSWER(s) with the flag set to 'true' (before sending the final ANSWER)?

Q2. Are there restrictions when it comes to changing information in a non-final answer and a final answer? Or, can the final answer be completely different from previously sent non-final ANSWERS? In "legacy" O/A there are restrictions.

Q3. Must the answerer wait for OK for a non-final ANSWER before sending a new ANSWER (non-final or final)?

Q4. If the answer to Q3 is "no", how does the answerer know to which ANSWER an OK message applies? AFAIK, the seq/sessionId values are identical for all ANSWERs associated with a specific OFFER.

Q5. The text says, that while the OFFER is "open", ie a final ANSWER has not been sent, the answerer is not allowed to send an OFFER. I assume that also applies to the offerer, ie it is not allowed to send a new OFFER until it has received a final ANSWER - even if it has received one or more non-final ANSWERs. Maybe it's obvious, but I think it would be good to explictily add some text about that (if my assumption is correct, that is :).



> -----Original Message-----
> From: 
> [] On Behalf Of Cullen Jennings
> Sent: 15. lokakuuta 2011 6:09
> To:;
> Cc: Jonathan Rosenberg
> Subject: [rtcweb] SDP Offer/Answer draft-jennings-rtcweb-signaling
> Jonathan and I submitted a new draft on setting up media 
> based on the SDP Offer/Answer model. The ASCII flows are a 
> bit hard to read so until I update them, I recommend reading 
> the PDF version at 
> Clearly the draft is an early stage but we plan to revise it 
> before the deadline for the IETF 82. Love to get input - 
> particularly on if this looks like generally the right 
> direction to go. 
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> rtcweb mailing list