答复: Re: 答复: Re: PRACK: Chan ge MUST requirement to include SDP offer in f irst reliable provisional response

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Newsgroups gmane.ietf.sipping
Message-ID <OF843EA60C.C6DB6893-ON48257597.0000690F-48257597.00008E30@zte.com.cn>
Hi,

Why you answer the mail you have answered? :)

And the newer mails(on 2009-04-09) you have not answered yet.

Thanks.

Gao





Christer Holmberg <[email protected]> 
发件人:  <[email protected]>
2009-04-07 15:43

收件人
<[email protected]>, Paul Kyzivat <[email protected]>
抄送
<[email protected]>, <[email protected]>
主题
Re: [Sipping]   答复: Re:  PRACK: Change MUST requirement to include SDP 
offer in        first reliable provisional response






Hi,
 
I think we already a while ago agreed on the principle that it shall be 
possible to send a non-200 response to a PRACK (not only for offer/answer, 
but possibly also due to other reasons).
 
And, in that case, why would an intermeidate be allowed to reject a PRACK, 
but not the UAS?
 
Regards,
 
Christer
 
 

From: [email protected] [mailto:[email protected]] On Behalf 
Of [email protected]
Sent: Tuesday, April 07, 2009 4:33 AM
To: Paul Kyzivat
Cc: [email protected]; [email protected]; Christer Holmberg
Subject: [Sipping] 答复: Re: PRACK: Change MUST requirement to include SDP 
offer in first reliable provisional response


More points of view to this question: 

By RFC3262: 
1. "Retransmissions of the reliable provisional response cease when a 
matching PRACK is received by the UA core." 

2. "If the PRACK does match an unacknowledged reliable provisional 
response, it MUST be responded to 
   with a 2xx response." 

So, when UAs receive a matching PRACK, it will stop re-transmit the 
reliable provisional response(18x). And the response 
to PRACK MUST be 2xx. 

It is simple and clear. And when UAs receive non-2xx response to PRACK, it 
is clear that the other side do not receive the 
PRACK. It can send a new PRACK(CSeq++, the same RAck). 

And now, we can use PRACK to send "precondition notification" and "codec 
refine". When we need to issue session modification like adding codec, 
adding/removing media streams, we MUST using Re-INVITE/UPDATE. 

I think we should not re-write RFC3262 to allow the UA to reject the 
PRACK. 





Paul Kyzivat <[email protected]> 
发件人:  [email protected] 
2009-04-06 20:16 


收件人
"Rockson Li (zhengyli)" <[email protected]> 
抄送
[email protected], Christer Holmberg <[email protected]> 
主题
Re: [Sipping] PRACK: Change MUST requirement to include SDP offer in  
first reliable provisional response








I think I also agree. There are a lot of things that in hindsight we 
probably would have done differently. But that is water over the dam. We 
are where we are.

                Paul

Rockson Li (zhengyli) wrote:
> I totally agree with Hadriel's insight here.
> 
> It should have been avoided to put too many jobs into PRACK,
> 
> I miss KISS(Keep It Simple and Stupid) principle
> 
> 
> 
> Regards,
> 
> -Rockson
> 
> ------------------------------------------------------------------------
> *From:* [email protected] [mailto:[email protected]] *On 
> Behalf Of *Hadriel Kaplan
> *Sent:* Tuesday, March 31, 2009 9:50 PM
> *To:* Christer Holmberg; [email protected]
> *Subject:* Re: [Sipping] PRACK: Change MUST requirement to include SDP 
> offer in first reliable provisional response
> 
> 
> 
> 
> 
> In hindsight I’m thinking we probably also shouldn’t have made the SDP 

> answer (or another offer) required or even possible in the PRACK 
> either.  I think it should have been for one and only one purpose: to 
> acknowledge receipt of the provisional response. 
> 
> 
> 
> -hadriel
> 
> 
> 
> 
> 
> 
> ------------------------------------------------------------------------
> 
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> This list is for NEW development of the application of SIP
> Use [email protected] for questions on current sip
> Use [email protected] for new developments of core SIP
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This list is for NEW development of the application of SIP
Use [email protected] for questions on current sip
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