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: sipping-bounces@xxxxxxxx [mailto:sipping-bounces@xxxxxxxx] On Behalf Of gao.yang2@xxxxxxxxxx
Sent: Tuesday, April 07, 2009 4:33 AM
To: Paul Kyzivat
Cc: sipping-bounces@xxxxxxxx; sipping@xxxxxxxx; 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
<pkyzivat@xxxxxxxxx> 发件人: sipping-bounces@xxxxxxxx 2009-04-06 20:16 |
|
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:* sipping-bounces@xxxxxxxx [mailto:sipping-bounces@xxxxxxxx] *On
> Behalf Of *Hadriel Kaplan
> *Sent:* Tuesday, March 31, 2009 9:50 PM
> *To:* Christer Holmberg; sipping@xxxxxxxx
> *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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