RE: [Sip] RE: Delivering request-URI and parameters to UAS via proxy -new version of the draft-holmberg-sip-target-uri-delivery draft

"Elwell, John" <john.elwell@siemens.com> Wed, 16 January 2008 13:52 UTC

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Date: Wed, 16 Jan 2008 13:52:32 +0000
From: "Elwell, John" <john.elwell@siemens.com>
Subject: RE: [Sip] RE: Delivering request-URI and parameters to UAS via proxy -new version of the draft-holmberg-sip-target-uri-delivery draft
In-reply-to: A <CA9998CD4A020D418654FCDEF4E707DF04173CB8@esealmw113.eemea.ericsson.se>
To: Christer Holmberg <christer.holmberg@ericsson.com>, sip@ietf.org
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Christer,

I don't think the entity using the mechanism needs to know about next
hop support for the loose route mechanism - only whether the UAS
supports it. If the UA registers, then the loose route draft provides an
automatic mechanism. If the UA does not register, support would need to
be indicated by provisioning. I am not sure this ranks as a significant
limitation, since a certain amount of provisioning needs to be done
anyway for UAs such as gateways that do not register.

John 

> -----Original Message-----
> From: Christer Holmberg [mailto:christer.holmberg@ericsson.com] 
> Sent: 16 January 2008 11:51
> To: Elwell, John; sip@ietf.org
> Cc: Paul Kyzivat; DRAGE,Keith (Keith); Francois Audet
> Subject: RE: [Sip] RE: Delivering request-URI and parameters 
> to UAS via proxy -new version of the 
> draft-holmberg-sip-target-uri-delivery draft
> 
> 
> Hi, 
> 
> >I hear what you are saying, but I don't really see that the 
> points you
> raised in section 4 are real limitations of the loose route mechanism.
> 
> I think it is a limitation that an entity using the mechanism has to
> know whether the the next hop supports it or not, and that 
> the mechanism
> can only be used if the subsequent hops support it.
> 
> Regards,
> 
> Christer
> 
> 
> 
> 
> > > -----Original Message-----
> > > From: Christer Holmberg [mailto:christer.holmberg@ericsson.com]
> > > Sent: 16 January 2008 11:06
> > > To: Elwell, John; sip@ietf.org
> > > Cc: Paul Kyzivat; DRAGE, Keith (Keith); Francois Audet
> > > Subject: [Sip] RE: Delivering request-URI and parameters 
> to UAS via 
> > > proxy - new version of the draft-holmberg-sip-target-uri-delivery 
> > > draft
> > > 
> > > 
> > > Hi John,
> > > 
> > > >Thanks for this revision, which makes things somewhat 
> > clearer. I do 
> > > >have a couple of comments:
> > > > 
> > > >1. I am not sure I agree with the assertions in section 4 
> > concerning 
> > > >issues with the mechanisms in loose-route. Taking example 1, the 
> > > >Route header field should contain enough entries to get 
> you to the 
> > > >registered contact, not just to an intermediate proxy. 
> > Therefore this 
> > > >situation should not arise with a correctly implemented 
> > home proxy. 
> > > >It is not clear to me how example 2 could arise either, 
> > for similar 
> > > >reasons. The MGC case can be resolved by taking into account the 
> > > >option tag in the REGISTER request, or if it is permanently 
> > > >registered, through provisioning.
> > > 
> > > The examples are not meant to show bugs in the loose-route 
> > mechanism.
> > > They are meant to help people understand the limitations with the 
> > > loose-route mechanism.
> > >  
> > > >2. Comparing the mechanism proposed with the loose-route 
> > mechanism, 
> > > >my understanding is:
> > > >a)When retargeting occurs, the loose-route mechanism 
> > places the new 
> > > >target in the Request URI. Your proposal places the new 
> target in 
> > > >both the Request-URI and the Target header field.
> > > >b) When rerouting, the loose-route mechanism places the 
> new route 
> > > >(i.e., the registered contact) in the Route header field. Your 
> > > >proposal places the new route in the Request-URI (the 
> > latter as per 
> > > >RFC 3261).
> > > >So the two mechanisms solve exactly the same problems using a 
> > > >slightly different mechanism. Correct?
> > > 
> > > Yes. The two solutions intend to solve the same problem.
> > >  
> > > >3. How P-Called-Party-ID fits into this is not really 
> > relevant from 
> > > >an IETF perspective - it seems there are some 3GPP-specific 
> > > >situations where the contents of P-Called-Party-ID will 
> > not equal the 
> > > >contents of Target. Correct?
> > > 
> > > Correct.
> > > 
> > > >4. If my suggestion in point 1 above that the loose-route 
> > mechanism 
> > > >does not suffer from the problems suggested, then each 
> > mechanism will 
> > > >work and each addresses the same problem.
> > > >So it is just down to a beauty contest between the two. Correct?
> > > 
> > > See question 1.
> > > 
> > > We believe that our solution does not have the same 
> > limitations as the 
> > > loose-route solution. But, again, both solutions intend to 
> > solve the 
> > > same problem.
> > > 
> > > Regards,
> > > 
> > > Christer
> > > 
> > > 
> > > 
> > > 
> > > 
> > > 
> > > > > -----Original Message-----
> > > > > From: Christer Holmberg 
> [mailto:christer.holmberg@ericsson.com]
> > > > > Sent: 16 January 2008 08:41
> > > > > To: sip@ietf.org
> > > > > Cc: DRAGE, Keith (Keith); Paul Kyzivat; Elwell, John; 
> > Jeroen van 
> > > > > Bemmel; Francois Audet
> > > > > Subject: Delivering request-URI and parameters to UAS via
> > > > proxy - new
> > > > > version of the draft-holmberg-sip-target-uri-delivery draft
> > > > > 
> > > > > 
> > > > > Hi,
> > > > > 
> > > > > We've uploaded a new version (-01) of the Target draft.
> > > > > 
> > > > > We've tried to make things more clear. I've also 
> > removed all text 
> > > > > about P-Called-Party-ID, except from one chapter where 
> > we try to 
> > > > > explain the semantical difference between Target and P-CPI.
> > > > > 
> > > > > You can also find the draft from:
> > > > > http://users.piuha.net/cholmber/drafts/draft-holmberg-sip-targ
> > > > > et-uri-del
> > > > > ivery-01.txt
> > > > > 
> > > > > Regards,
> > > > > 
> > > > > Christer
> > > > > 
> > > > 
> > > 
> > > 
> > > _______________________________________________
> > > Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
> > > This list is for NEW development of the core SIP Protocol Use 
> > > sip-implementors@cs.columbia.edu for questions on current sip Use 
> > > sipping@ietf.org for new developments on the application of sip
> > > 
> > 
> > 
> > _______________________________________________
> > Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
> > This list is for NEW development of the core SIP Protocol Use 
> > sip-implementors@cs.columbia.edu for questions on current sip 
> > Use sipping@ietf.org for new developments on the application of sip
> > 
> 


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