Adding something about rejecting.
*pure* preconditon notification is just refreshing state table defined in RFC3312. So, *pure* preconditon notification can not be rejected by RFC3312.
And I think others in session *modification request* can be rejected, including "codec refine"(though "codec refine" almost not be rejected).
| "Christer Holmberg"
<christer.holmberg@xxxxxxxxxxxx>
2009-04-07 19:33 |
|
Hi,
>>I mean rejectable in app-level. 491 is beneath app-level.
>> And precondition notification is not a rejectable usage in app-level.
>
>Ok, so where is all that defined?
>
>[Gao] By RFC3312: The offerer generates a transaction
> status table, identical to its local status table, and sends it to
> the answerer in the offer. The answerer uses the information of this
> transaction status table to update its local status table. The
> answerer also updates the transaction status table fields that were
> out of date and returns this table to the offerer in the answer. The
> offerer can then update its local status table with the information
> received in the answer. After this offer/answer exchange, the local
> status tables of both user agents are synchronised.
>
>The precondition state is just notification/updating, not negotiating.
And where is it said that a notification/updating request cannot be rejected?
I have nothing against recommending that PRACKs are only used for notifications etc, but I don't think that will ensure that a PRACK is never rejected.
>>BTW, I saw some points of view (just today and yesterday) which want to make it simple.
>
>I also want to make it simple.
>
>Saying that something must never happen is a very simple solution. We sould do that for other things also, and our specs would become very short... :)
>
>[Gao] I am not sure we are talking the same thing :)
>I mean that some people do not want modification here.
I am only talking based on agreements we have made. If the group decides to change those agreements - fine.
Regards,
Christer
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).
>
>[Gao] Then, it is a modification of RFC3262.
Yes.
>And, in that case, why would an intermeidate be allowed to reject a PRACK, but not the UAS?
>
>[Gao] I think, by RFC3262, it is not suitable to put too much usage in the PRACK to make it rejectable.
Every request is rejectable, no matter how much or little usage you have in it.
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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