Re: [Sip] Comparison of retargeting proposals

["Francois Audet" <audet at nortel.com>]

Re-Targeting (RTRG) is when a Proxy changes a Request-URI to a different one, outside of
normal routing.  That's ok. For example, bob at example.com to alice at example.com.

What is the difference between RRT (Re-Routing) and Routing (Routing)? I don't get it.

And I don't see in here the place where the Request-URI is changed to the Contact
that was used in the REGISTER (i.e., where example.com changes bob at example.com to
bob at bobpc.example.com). That is really the missing part, no?

Is that what you call RRT? And if so, why is there an extra leg between it and the
UAS? Is it because P4 is an outbound proxy?

And I still don't see why C != E. It would only be different if loose route was not
used by the proxies (e.g., RFC 2543 proxies). Is that what you mean? If so, doesn't this
mean P-Called-Party-ID is essentially useless and IMS can't use it anyways? So we should 
just fix P-Called-Party-ID spec instead?

> -----Original Message-----
> From: Hadriel Kaplan [mailto:HKaplan at acmepacket.com] 
> Sent: Wednesday, April 02, 2008 13:22
> To: Audet, Francois (SC100:3055); Christer Holmberg; Hans 
> Erik van Elburg; Juha Heinanen
> Cc: sip at ietf.org; DOLLY, MARTIN C, ATTLABS
> Subject: RE: [Sip] Comparison of retargeting proposals
> 
> 
> 
> > -----Original Message-----
> > From: sip-bounces at ietf.org [mailto:sip-bounces at ietf.org] On 
> Behalf Of 
> > Francois Audet
> >
> > Can you give one. It seems to me that in both cases, the 
> headers will 
> > include the last Request-URI "just before it's replaced by 
> the Contact 
> > used in Registration".
> 
> From a previous email I sent a long time ago, given the 
> following reasonably complex scenario, where "RTRG" means 
> Re-Targeting, "RRT" means Re-Routing, "RT" means Routing, and 
> the single letters represent connections:
> 
>                     RTRG                    RRT
>                    +---+                   +---+
>                    |R1 |                   |R2 |
>                 B /+---+\ C             E /+---+\ F
>             RT   /       \  RT      RT   /       \  RT
>            +---+/         \+---+ D +---+/         \+---+
>            |P1 |           |P2 +---+P3 |           |P4 |
>         A /+---+           +---+   +---+           +---+\ G
>          /                                               \
>    +---+/                                                 \+---+
>    |UAC|                                                   |UAS|
>    +---+                                                   +---+
> 
> Goal: to get the req-uri seen on "C" (right?).
> 
> UA-Loose-routing sets the req-uri to that seen on connection "C".
> Target gives you C.
> PCPID gives you E.
> Hist-Info gives you A,B,C,D,E,F.
> To header gives you A.
> 
> C != E, because P2 and P3 could be swapping req-uri's as they 
> 3261 route.  UALR draft says "stop swapping when you route", 
> but Target draft does not.
> 
> -hadriel
> 
> 
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