1. the situation of inconsistent media level
UAC UAS
Re-INVITE---------->(Offer)
<----------------183(Answer)
PRACK-------------->
Offer is optional;
Answer is mandatory;
UAS is the resumer of suspended session, so:
A UAS that is not capable of unilaterally meeting all of the
mandatory preconditions MUST include a confirm-status attribute in
the SDP (offer or answer) that it sends (see Section 7).
If UAC do not conf the UAS，UAC could never see the Precondition OK by SDP.
So, it can be that UAS see the Precondition OK, but UAC do not.
Then, after 4xx of Re-INVITE, UAS's "in use" media is the one after Re-INVITE. In your examle, that is:
audio stream: audio codec 2
video stream: video codec 2 (subject to preconditions OK)
And UAC's "in use" media is the one before Re-INVITE.
audio stream: audio codec 2
video stream: video codec 1 (subject to preconditions is not OK)
You tell me yesterday:
If you could provide a valid example, it would help us understand
if there is a problem here.
In any case, if endpoints end up with an inconsistent view of the
parameters in use, it would be a bigger problem than the issue we are
talking about here, because it would mean that the media session between
them would not work.
I think it is. Do you think it is? YES/NO
2. illegal of media use
It is a real problem, no matter in signalling level what the state should be.
I want to ask could end user using the session parameters? YES/NO
3. violation of session continuity
It is a real problem. Do you think so? YES/NO
And the accessorial is that is it the most case?
I know your answer.
| Gonzalo Camarillo <Gonzalo.Camarillo@xxxxxxxxxxxx>
2009-02-27 16:40 |
|
Hi,
I have already addressed your concerns on the three points below in this
email thread. If you think something is not completely or properly
addressed, explain it or provide an example. Going in circles and
discussing again what we have already discussed would be pointless.
Thanks,
Gonzalo
gao.yang2@xxxxxxxxxx wrote:
>
> Dear Gonzalo Camarillo
>
> And I think:
>
> 1. the situation of inconsistent media level
>
> 2. illegal of media use
>
> 3. violation of session continuity
>
> Still exist.
>
> And talking about "the situation of inconsistent media level", I just
> talk the session state can be inconsistent from two sides.
> But you think it is "signalling-media synchronization" issue. I do not
> think it is.
>
> And talking "illegal of media use", you restrcited me talking media
> level usage.
>
> And talking "violation of session continuity", you think it is not the
> most case.
>
> Gao
>
>
>
>
> *Gonzalo Camarillo <Gonzalo.Camarillo@xxxxxxxxxxxx>*
>
> 2009-02-27 16:08
>
>
> 收件人
> gao.yang2@xxxxxxxxxx
> 抄送
> christer.holmberg@xxxxxxxxxxxx, sipping@xxxxxxxx
> 主题
> Re: 答复: Re: [Sipping] Closing the offer/answer rollback issue
> //discussion: the situation of inconsistent media level
>
>
>
>
>
>
>
>
> Hi,
>
> > Current definition of "in use" is the one proposed by Holmberg yesterday:
>
> no, we are discussing the proposal in my original email. As I have said
> before, the idea is to have focused discussions without jumping from
> topic to topic before resolving any of them.
>
> In any case, so far we have not found any requirement that would not be
> met by the straw-man proposal in my original email. If we do not find
> any soon, we will be making a decision shortly.
>
> Cheers,
>
> Gonzalo
>
>
>
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