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RE: [AVT] Offer/answer questions on RFC 4585

"Christer Holmberg" <christer.holmberg@ericsson.com> Tue, 02 October 2007 12:13 UTC

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Subject: RE: [AVT] Offer/answer questions on RFC 4585
Date: Tue, 02 Oct 2007 14:13:19 +0200
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Thread-Topic: RE: [AVT] Offer/answer questions on RFC 4585
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From: Christer Holmberg <christer.holmberg@ericsson.com>
To: avt@ietf.org
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Hi Roni,

>>I have a couple of questions on RFC 4585, regarding the usage with
offer/answer.
>>
>>My FIRST question is: are there any TECHNICAL reasons (I know it's
probably not allowed by RFC 3264) why a user receiving an AVPF offer,
but doesn't 
>>support it, can't reply with AVP answer (instead of rejecting the
stream)? My understanding is that if you offer AVPF you still have to be
able to do 
>>AVP, so...
>>(The receiver of course needs to understand the "AVPF" string in the
SDP)

>[RE:] I think that is this case the offer will include a=rtcp-fb with
rtcp-fb-vals. Since the receiver understands AVPF but do not support any
feedback 
>message it will remove all rtcp-fb-val in the answers.
>To me that looks like support of AVP so why do you want to change the
avpf to avp.

Ok, if it works that way.

So, if I have an MGCF/MGW I can do the following:

- The MGCF answers with AVPF, but without rtcp-fb-val

- The MGCF sends AVP down to the MGW (e.g using H.248)

Regards,

Christer



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