Re: Outbound and mid-dialog requests with GRUU

On Oct 17, 2008, at 12:21 PM, Paul Kyzivat wrote:

>
>
> Dean Willis wrote:
>> Here's a question:
>> A UA has registered two flows to one instance. It has one gruu. The  
>> UA uses the gruu as the contact in a dialog-forming request.
>> An in-dialog request (for example, BYE) is sent back  to the UA. On  
>> which flow does it get routed?
>
> From gruu-15:
>
>
>   1.  The client is using draft-ietf-sip-outbound [13] and registering
>       multiple contacts for redundancy.  In that case, these contacts
>       contain reg-id Contact header field parameters, and the rules
>       described in Section 7 of draft-ietf-sip-outbound [13] for
>       selecting a single registered contact apply.



Not helpful; section 7 refers to out-of-dialog request forwarding.

What happens to in-dialog requests?

The request references a gruu.

A pre-outbound gruu is bound to one and only one contact, so the  
request-URI transformation rule is obvious; transform the request-URI  
using the contact associated with the gruu. This behavior is specified  
in 6.1 of the gruu draft. Oddly enough, that text in gruu-6.1 replaces  
the request-URI with "the registered contacts" (note the plural). Not  
sure that makes sense. Somebody tell me if that's a bug in gruu.

An outbound-compliant gruu is bound to one and only instance, but an  
instance can have multiple contacts.

I think what has to happen to make it work is fairly obvious, but it  
isn't documented anywhere I can find.

There's some hinting at it in outbound-5.3.2, but inly from the  
perspective of the edge proxy. What has to happen at the home proxy to  
make this work?

--
Dean


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