Re: SIPit 21: Question about offer answer

Hisham Khartabil wrote:
> My view on this is that if you don't want to send SDP
but you have to 
> when sending a re-INVITE, then send UPDATE without the
SDP. Can we 
> update session timer to say that?

I suppose we could, but you can only do that if both sides
support 
UPDATE. Since its optional, those who implement session
timer must be 
prepared to do it with reINVITE.

I really don't understand the issue here. If you send a
reINVITE with 
unchanged SDP and you get back an answer that is changed,
just deal with 
it. Why is this a problem?

	Paul

> Hisham
> 
>  
> On 21/11/2007, *Paul Kyzivat* <pkyzivatcisco.com

> <mailto:pkyzivatcisco.com>> wrote:
> 
> 
> 
>     Christer Holmberg wrote:
>      > Hi,
>      >
>      > What if the offerer is not
"prepared" to receive an updated
>     answer (it
>      > only included the "offer" because
it had to)? How can it "reject" the
>      > answer?
> 
>     It can't. At best it can make a counter offer after
the fact, or
>     terminate the call after the fact.
> 
>     But that clearly isn't a good policy. You should
design your UA so that
>     this isn't an issue. When you make an offer you
must always be prepared
>     for the answer be anything that is compatible with
the offer.
> 
>      > I personally think that an unchanged o- line
in the offer should not
>      > allow the answer to change.
>      >
>      > One could of course change the o- line in the
offer - even if the
>     offer
>      > itself hasn't changed - and that would then
allow the answer to be
>      > changed.
> 
>     Personally I think the o-line changing or not is
just an extra
>     complication that should never have been there as a
factor. Whether the
>     o-line changes or not isn't what matters. What
matters is whether the
>     rest of the SDP changes. At best the o-line is a
hint about whether the
>     rest changed or not, and simply introduces the
potential error case
>     where the SDP doesn't agree with what the o-line is
hinting. (So what
>     should you do if the o-line is unchanged but the
SDP is changed?)
> 
>     But as things are written, you are expected to make
the o-line the same
>     if the rest of the SDP is the same. The o-line in
the offer has
>     *nothing* to do with what is in the answer.
> 
>            Paul
> 
>      > Just some thinking...
>      >
>      > Regards,
>      >
>      > Christer
>      >
>      >
>      >
>      >> -----Original Message-----
>      >> From: Dale.Worleycomcast.net <mailtoale.Worl
eycomcast.net>
>     [mailtoale.Worl
eycomcast.net <mailtoale.Worl
eycomcast.net>]
>      >> Sent: 20. marraskuuta 2007 3:39
>      >> To: sipietf.org <mailto:sipietf.org>
>      >> Subject: Re: [Sip] SIPit 21: Question
about offer answer
>      >>
>      >>    From: Paul Kyzivat <pkyzivatcisco.com
>     <mailto:pkyzivatcisco.com>>
>      >>
>      >>    A 3pcc controller doing a transfer may
well send an
>      >> offerless invite to
>      >>    one UA and then send the offer it gets
back to an entirely
>      >> different UA
>      >>    than had been in the session before.
So of course the
>      >> answer will be
>      >>    entirely different.
>      >>
>      >> Hmmm, "my" music-on-hold
proposal does that, too.
>      >>
>      >> Dale
>      >>
>      >>
>      >>
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>     developments on the application of sip
>      >>
>      >
>      >
>      >
_______________________________________________
>      > Sip mailing list  https://ww
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>      > This list is for NEW development of the core
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>      > Use sip-implementorscs.columbia.edu
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<mailto:sippingietf.org> for new
>     developments on the application of sip
>      >
> 
> 
>     _______________________________________________
>     Sip mailing list  https://ww
w1.ietf.org/mailman/listinfo/sip
>     This list is for NEW development of the core SIP
Protocol
>     Use sip-implementorscs.columbia.edu
>     <mailto:sip-implementorscs.columbia.edu> for
questions on current sip
>     Use sippingietf.org <mailto:sippingietf.org> for new developments
>     on the application of sip
> 
> 

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Re: SIPit 21: Question about offer answer

Thread: Re: SIPit 21: Question about offer answer