Re: [Sipping] 答复: Re: 答复: Re: 答复: Re: 答复: Re: 答复: Re: 答复: Re: 答复: Re: Closing the offer/answer rollback issue

[Gonzalo Camarillo <Gonzalo.Camarillo at ericsson.com>]

Hi,

> [Gao] RFC3261:
> If a UA receives a non-2xx final response to a re-INVITE, the session
>    parameters MUST remain unchanged, as if no re-INVITE had been issued.
> 
> However, the
>    failure of the re-INVITE does not cause the existing call to fail -
>    the session continues using the previously negotiated
>    characteristics.  

yes, as I explained in my original email, the consensus in the WG has
been that we are willing to lose this atomicity property. It is a
tradeoff between keeping that property and doing the right thing.

> [Gao] Why think after 4xx, the "most" case is that user prefer to using 
> the media negotiated in Re-INVITE.
> I think rejecting is the "most" case.
> But this is subjective branching :).

the assumption we are working on is that the user would prefer that the
failure of the re-INVITE does not trigger a sudden media change. That
is, the media session would continue unchanged when the 4xx for the
re-INVITE arrives.

> if a stream is rejected, it will not be in use. We do not indent to
> change that rule anywhere.
> 
> [Gao] I think the usage should be restricted by signaling, while not end 
> users' consciousness. :)

We are talking about signalling here.

Cheers,

Gonzalo