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" <[e-mail]>]

Christer,

We still seem to have a disconnect in our understanding. See below.

John 

> -----Original Message-----
> From: Christer Holmberg [mailto:[e-mail]] 
> Sent: 16 January 2008 14:32
> To: Elwell, John; [e-mail]
> 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
> 
> 
> John,
> 
> According to the UA-loose-route draft, every proxy in the path need to
> support the mechanism in order for the "current target" to be retained
> in the R-URI. A good example is the "Service Invocation" use 
> case in the
> UA loose route draft.
[JRE] The Service Invocation section in loose-route tells me nothing
about proxies on the path. It simply talks about invocation of a service
at the UAS.

> 
> Maybe the "loose route" wording is confusing (I think it is also
> mentioned in the UA-loose-route draft that a better naming may be
> needed)?
> 
> Also, maybe one can assume that a home proxy knows what entities not
> registering (MGCs etc) support. But, again, we are not only talking
> about home proxies.
[JRE] Surely it is only the home proxy that takes an AoR and determines
a contact URI to route to. Maybe my understanding of home proxy is
different.

> 
> Regards,
> 
> Christer 
> 
> 
> 
> 
> 
> > -----Original Message-----
> > From: Elwell, John [mailto:[e-mail]] 
> > Sent: 16. tammikuuta 2008 15:53
> > To: Christer Holmberg; [e-mail]
> > 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
> > 
> > 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:[e-mail]]
> > > Sent: 16 January 2008 11:51
> > > To: Elwell, John; [e-mail]
> > > 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:[e-mail]]
> > > > > Sent: 16 January 2008 11:06
> > > > > To: Elwell, John; [e-mail]
> > > > > 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:[e-mail]]
> > > > > > > Sent: 16 January 2008 08:41
> > > > > > > To: [e-mail]
> > > > > > > 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
> > > > > > > 
> > > > > > 
> > > > > 
> > > > > 
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> > > > 
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> > > 
> > 
> 
> 
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