Subject: Re: [MEDIACTRL] SIP Control Framework

From: Sukanta ganguly <[email-masked]>
Date: Sun, 14 Oct 2007 08:36:48 -0700 (PDT)

I agree that the SBC and the active gateways do modify the tags and once they are modified uniqueness is difficult to maintain. So some other construct needs to be defined that can act as meta-tag.

SG

----- Original Message ----
From: Lorenzo Miniero <[email-masked]>
To: Christer Holmberg <[email-masked]>
Cc: [email-masked]
Sent: Sunday, October 14, 2007 8:16:58 AM
Subject: Re: [MEDIACTRL] SIP Control Framework

Hi Christer,

however, even if these tags are modified, once they've been setup they still 
should unique for each point-to-point SIP dialog, aren't they? If that's the 
case, the tags would still do the job anyway, considering each pair addresses 
a specific dialog between an AS and a MS. If not, you're absolutely right, 
and an alternative addressing solution should be considered.

Lorenzo

On Sunday 14 October 2007 17:00:52 Christer Holmberg wrote:
> Hi,
>
> I am not sure whether using the from- and/or to-tags to identify is the
> best solution. SBCs have a tendence to modify those along the path.
>
> Regards,
>
> Christer
>
> > -----Original Message-----
> > From: Salvatore Loreto [mailto:[email-masked]]
> > Sent: 8. lokakuuta 2007 17:20
> > To: Lorenzo Miniero
> > Cc: [email-masked]
> > Subject: Re: [MEDIACTRL] SIP Control Framework
> >
> > Hi Lorenzo,
> >
> > you are right Dialog-ID and connection-id are two different
> > things, and I see the way they are different, more or less
> >
> > :-) What confused me it is see in Section 7 the reference to
> >
> >     "See syntax defined in Section 16.1 in Appendix A and
> > examples in Section 9.6."
> >
> > Then we could start to argue it a from-tag and the to-tag are
> > enough to identify a resource inside a dialog.
> >
> > sal
> >
> > On Mon, 2007-10-08 at 15:16 +0200, Lorenzo Miniero wrote:
> > > Hi Salvatore,
> > >
> > > just a quick note inline upon one of the points you raised.
> > >
> > > <cut>
> > >
> > > > In Section 7 you state:
> > > >
> > > >    o  The 'Dialog-ID' message header is constructed by
> >
> > concatenating the
> >
> > > >       Local-tag, Call-ID and Remote-tag (as defined in
> >
> > Section 11.1)
> >
> > > >       from the SIP dialog and separating with a '~'.  See
> >
> > syntax defined
> >
> > > >       in Section 16.1 in Appendix A and examples in
> >
> > Section 9.6.  For
> >
> > > >       example, if the SIP dialog had values of 'Local-tag=HKJDH',
> > > >       'Remote-tag=JJSUSHJ' and
> >
> > 'Call-ID=[email-masked]' - the
> >
> > > >       'Dialog-ID' header would look like this:
> > > >       'Dialog-ID=[email-masked]~JJSUSHJ'.
> > > >
> > > > but then in 16.1 there is an error, because you don't use
> >
> > the Call-ID at all:
> > > >    If used within a
> > > >    package, the value contained in the 'connection-id'
> >
> > attribute MUST be
> >
> > > >    constructed by concatenating the 'Local' and 'Remote'
> >
> > SIP dialog
> >
> > > >    identifier tags as defined in RFC3261 [2].  They MUST then be
> > > >    separated using the '~' character.  So the format would be:
> > > >
> > > >                'Local Dialog tag' + '~' + 'Remote Dialog tag'
> > >
> > > The Dialog-ID refers to the identifier needed to correlate an
> > > AS-related SIP Dialog, i.e. a SIP dialog which is handling/going to
> > > handle a control channel, with the control channel itself. The
> > > connection-id, instead, refers to the negotiated media
> >
> > connection(s)
> >
> > > (e.g. audio or
> > > video) the MS is needed to manage. So they are not the same
> >
> > identifier.
> >
> > > Whether the connection-id as it is conceived is enough to always
> > > univocally address a connection or not (as the Dialog-ID does),
> > > instead, is another matter. Having it formed as the
> >
> > Dialog-ID may help
> >
> > > in this sense, even if I think it would add unneeded redundancy and
> > > probably weigh down the whole control channel communication.
> > >
> > >
> > > Cheers,
> > > Lorenzo
> >
> > _______________________________________________
> > MEDIACTRL mailing list
> > [email-masked]
> > https://www1.ietf.org/mailman/listinfo/mediactrl
> > Supplemental Web Site:
> > http://www.standardstrack.com/ietf/mediactrl

-- 
Lorenzo Miniero, Junior Researcher
Dipartimento di Informatica e Sistemistica
Università degli Studi di Napoli "Federico II"
Via Claudio 21 -- 80125 Napoli (Italy)
Phone: +390817683821 - Fax: +390817683816
Email: [email-masked]

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