RE: [Sip] Vocabulary and problem statement for Request-URI, retargeting, and SIP routing (long, but read it!)

[Hadriel Kaplan <[e-mail]>]

> -----Original Message-----
> From: Dean Willis [mailto:[e-mail]]
> Sent: Thursday, January 17, 2008 6:45 PM
>
> AFAIK, the original goal of UALR was to get parameters to applications.
> The last time I thought I understood the draft, these were preserved
> back somewhere on teh route stack so that the application could get them.

That may have been the intent, but as I read draft-rosenberg-sip-ua-loose-route-01.txt, it doesn't do that if a retarget occurs.  In a retargeting case the req-uri is replaced with the new target.  In the rerouting case, the req-uri is left alone, and the newly resolved destination URI (for lack of a better term) would be pushed as a Route header.

It does, though, say the previous req-uri would be pushed into the History-Info header.  It would have been before this draft too, if people implemented it, except with this new draft ONLY retarget cases would push a History-Info.  So I guess in that sense you're right, the pre-retargeting data could be there in that.


> >
> > But in the re-targeting scenario such as:
> >                     RTRG                    RRT
> >                    +---+                   +---+
> >                    |R1 |                   |R2 |
> >                 B /+---+\ C             E /+---+\ F
> >             RT   /       \  RT      RT   /       \  RT
> >            +---+/         \+---+ D +---+/         \+---+
> >            |P1 |           |P2 +---+P3 |           |P4 |
> >         A /+---+           +---+   +---+           +---+\ G
> >          /                                               \
> >    +---+/                                                 \+---+
> >    |UAC|                                                   |UAS|
> >    +---+                                                   +---+
> >
> > UA-Loose-routing wants the req-uri seen on connection "C" I think.
> > To header gives you A.
> > PCPID gives you E.
> > Hist-Info gives you A,B,C,D,E,F.
>
> As I thought I understood it, UALR gives us the stack of A and C.

If R1 and R2 did UALR, the UAS would get the req-uri from C, a History-Info with B, and there'd be a Route header with UAS' contact.

-hadriel



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