Subject: Re: [Sipping] Question on dialog construction

From: "Peili Xu" <[email-masked]>
Date: Sat, 1 Sep 2007 22:13:42 +0800

Hi Rockson,

Maybe it will be helpful for you to read rfc4916 which talks about
"Connected Identity in the Session Initiation Protocol (SIP)"

Peili

2007/8/31, Rockson Li (zhengyli) <[email-masked]>:
>
>
> Tanu,
>
> Thanks, it's confirmed with my initial thoughts.
> But I just wonder why the spec does not permit remote target change from
> early dialog to confirmed dialog as route set?
> which looks just like adding an extra sentence.
>
> and in early dialog, as I said earlier, called UA could be moving somewhere,
> why not permit remote target update there in spec,
> I am not totally sure the rationale behind.
>
> Regards,
> -Rockson
>
>  ________________________________
>  From: Tanu Kapoor [mailto:[email-masked]]
> Sent: Friday, August 31, 2007 7:43 PM
> To: Rockson Li (zhengyli)
> Cc: [email-masked]; [email-masked]
> Subject: Re: [Sipping] Question on dialog construction
>
>
>
> Hi,
>
> To my understanding, the 1xx response cannot update the dialog routeset. The
> dialog routeset will be modified only with the 2xx reponse and further
> requests within dialog will not update the routeset of the dialog, but the
> target refresh request( Re-invite for a dialog established iwth Invite) can
> update the remote target URI.
>
> Regards,
> -Tanu.
>
>
> On 8/31/07, Rockson Li (zhengyli) <[email-masked]> wrote:
> > Hi, currently we have some disputes on routeset and remote target update
> > in early and confirmed dialog.
> >
> > questions are,
> >
> > 1) can routeset and contact be updated with 1xx response to ini-INVITE
> > in early dialog?
> >     like
> >
> >      A                          B
> >              INVITE
> >        ------------------------->
> >             First  1xx with contact ,to tag and Record-Route
> >        <-------------------------
> >             Second  1xx with contact ,to tag and Record-Route
> >        <-------------------------
> >
> >     can second 1xx update the early dialog's routeset and remote
> > target, which is created by first 1xx.
> >     From the 3261, looks not it can NOT
> >     Section 12.1.2:
> >
> >        When a UAC receives a response that establishes a dialog, it
> >        constructs the state of the dialog. This state MUST be
> > maintained
> >        for the duration of the dialog.
> >
> >        But why? If B is a mobile moving to somewhere else.....
> >
> > 2)         A                          B
> >              INVITE
> >        ------------------------->
> >             First  1xx with contact ,to tag and Record-Route
> >        <-------------------------
> >             Second  1xx with contact ,to tag and Record-Route
> >        <-------------------------
> >            2xx
> >        <-------------------------
> >
> > When dialog change to confirmed state on receipt of 2xx,  3261 says
> >
> > sec 13.2.2.4
> > If the dialog identifier in the 2xx response matches the dialog
> > identifier of an existing dialog, the dialog MUST be transitioned to
> > the "confirmed" state, and the route set for the dialog MUST be
> > recomputed based on the 2xx response using the procedures of Section
> > 12.2.1.2. Otherwise, a new dialog in the "confirmed" state MUST be
> > constructed using the procedures of Section 12.1.2.
> >
> > How about update remote target?
> > Does  2xx with different contact from previous 1xx make sense?
> >
> >
> > Regards,
> > Rockson Li (Zhengyu Li)
> >
> > Software Engineer
> > Cisco R&D Center, Shanghai, PRC
> > Phone(Office) : (8621) 24057003
> > Email: [email-masked]
> >
> >
> >
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> >
>
>
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