Re: [Sipping] Is SDP in an unreliable response "the answer" ???

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Hi, 

>> I don't disagree with what people are saying, but trying to read it 
>> from a I-am-a-new-implementor-and-I-would-like-to-get-it-right-from-
>> the-beginning perspective I don't think anything is clarified. Eg. 
>> talking about that an SDP sent after the answer would be 
>> "missunderstood as a new offer" is confusing. 
>	
>	I guess "missunderstood as a new offer" issue is clear: 
>	If the session-id of o= line is the same the ANSWER, UAC can treate it as just COPY of the answer; 
>	If the session-id is higher than the ANSWER's session-id, the UAC can treate it as *new* offer. As the UAC MUST ignore any SDP after ANSWER, it is OK for UAC doing nothing. But if UAC checks the SDP and find it is 
>	*new* offer and violation of O/A rules then terminate the session, I also think it is also OK(UAS do bad behavior at first). 

I am not talking about the UAC procedure. I fully support saying that the UAC ignores the SDP.

My problem is to say that the UAS shall not include SDP, because the UAC could "missunderstand it as a new offer". All we need to say is that the UAS MUST NOT include a new SDP.
	
Regards,

Christer













	> > -----Original Message-----
	> > From: sipping-bounces@xxxxxxxx 
	> > [mailto:sipping-bounces@xxxxxxxx] On Behalf Of OKUMURA Shinji
	> > Sent: 21. huhtikuuta 2010 8:45
	> > To: sipping@xxxxxxxx
	> > Subject: Re: [Sipping] Is SDP in an unreliable response "the 
	> > answer" ???
	> > 
	> > Hi,
	> > 
	> > Hans Erik van Elburg <ietf.hanserik@xxxxxxxxx> Tue, 20 Apr 
	> > 2010 21:53:17 +0200
	> > >On Tue, Apr 20, 2010 at 3:47 PM, Paul Kyzivat 
	> > <pkyzivat@xxxxxxxxx> wrote:
	> > >> Here is my attempt at summarizing the discussion conclusions:
	> > >>
	> > >> Normative things (stated or implied in existing RFCs):
	> > >>
	> > >> - If the UAC sent an offer in the INVITE, then after it 
	> > receives SDP 
	> > >> (the
	> > >> answer) in a reliable response to the INVITE, any SDP in 
	> > subsequent 
	> > >> responses to the INVITE MUST be ignored.
	> > >>
	> > >> - Further, if SDP is received in an unreliable response to 
	> > the invite 
	> > >> prior to receiving SDP in a reliable response, then it MUST be 
	> > >> treated as the answer for purposes of media processing, 
	> > but not for 
	> > >> purposes of determining when another offer may be sent or received.
	> > >>
	> > >[HE] I miss what the UAC should do in this case for subsequent 
	> > >responses, does the following hold as well:
	> > >"If the UAC sent an offer in the INVITE, then after it receives SDP 
	> > >(the answer) in an unreliable response to the INVITE, any SDP in 
	> > >subsequent responses to the INVITE MUST be ignored/granted/... ." ?
	> > 
	> > I agree. And it's certainly "ignored".
	> > 
	> > >Regardless what the correct behaviour is, it is missing in 
	> > your summary.
	> > >
	> > >> - if the UAS receives an offer in the INVITE, it MUST NOT 
	> > include SDP 
	> > >> in any response it sends until it has determined the 
	> > intended answer 
	> > >> SDP to the offer.
	> > >>
	> > >> - once the intended answer SDP is determined, it MUST be sent in a 
	> > >> reliable response to the INVITE. It MAY be sent in one or more 
	> > >> *preceding* unreliable provisional responses.
	> > >>
	> > >> Non-normative, best practice suggestions:
	> > >>
	> > >> - if the UAS receives an offer in the invite, once it has sent the 
	> > >> answer in a reliable response, it should not send any SDP in 
	> > >> subsequent responses to the INVITE.
	> > _______________________________________________
	> > Sipping mailing list  https://www.ietf.org/mailman/listinfo/sipping
	> > This list is for NEW development of the application of SIP 
	> > Use sip-implementors@xxxxxxxxxxxxxxx for questions on current 
	> > sip Use sip@xxxxxxxx for new developments of core SIP
	> > 
	> _______________________________________________
	> Sipping mailing list  https://www.ietf.org/mailman/listinfo/sipping
	> This list is for NEW development of the application of SIP
	> Use sip-implementors@xxxxxxxxxxxxxxx for questions on current sip
	> Use sip@xxxxxxxx for new developments of core SIP
	> 
	
	
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