RE: [Sip] RE: Delivering request-URI and parameters to UAS via proxy

"Christer Holmberg" <christer.holmberg@ericsson.com> Mon, 14 January 2008 11:56 UTC

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Subject: RE: [Sip] RE: Delivering request-URI and parameters to UAS via proxy
Date: Mon, 14 Jan 2008 12:56:15 +0100
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From: "Christer Holmberg" <christer.holmberg@ericsson.com>
To: "Francois Audet" <audet@nortel.com>
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Cc: sip@ietf.org, "Elwell, John" <john.elwell@siemens.com>, Paul Kyzivat <pkyzivat@cisco.com>, "DRAGE, Keith \(Keith\)" <drage@alcatel-lucent.com>
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Hi Francois, 

>I think what you meant by Target was more the "Current" 
>target as opposed to the Initiatl Target.

Yes.
 
>And if that's the case, then I don't see why it is different 
>from P-Called-ID (although I might be missing something with 
>what the P-Called_ID is supposed to be).

In the draft we try to explain the difference. But, we are working on
the text to make it more clear.

The P-CPI is inserted when the R-URI is rewritten by the Contact address
of the UAS. RFC3455 calls that operation "retargeting", but we don't
think that is the definition for retarget used in the ua-loose-route
draft, which says:

"When a home proxy receives a request and accesses a location
service, the resulting contact(s) obtained from the location
service are considered the last hop in the route towards the
entity addressed by the Request-URI.  Since that target, almost
by definition, can claim the identity of the URI prior to
translation, the operation is one of routing and not retargeting."

So, if we follow the definitions in the ua-loose-route draft, P-CPI
would be inserted due to a reroute - not retarget.

But, no matter whether we call it retarget or reroute, the point is that
the P-CPI is inserted when the R-URI is rewritten with the Contact
address of the UAS. The scope of Target is wider than that, and can be
used in any retargeting situation.

Regards,

Christer



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