Subject: [Sip] Re: GRUU-10: in-vs-out-of-dialog gruu retargetting

From: Jonathan Rosenberg <[email-masked]>
Date: Mon, 11 Sep 2006 09:15:49 -0400

inline.

Robert Sparks wrote:

> I forced myself (1) to forget the various conversations we had around  
> last-hop-spiraling and the interaction of GRUU with outbound and  tried 
> to read the proxy behavior section from the point-of-view of an  
> implementer who didn't have the list/meeting history in their head.  
> With those preconditions 8.2.1 through 8.2.3 get somewhat confusing.

You are not alone. Others have commented on this too, clearly it is 
needing some work.

> 
> First - It's not clear why there's any distinction between in-dialog  
> and out-of-dialog requests in the first place.
> That distinction isn't normal for a proxy - what's special that makes  
> it normal here?

Well... to be frank at this point its an artifact from previous 
revisions, where there really was quite different behavior. As of -9 or 
-10 or something they became more aligned, but it was incrementally 
edited towards that.

So, I would be inclined to unify the two sections. The one thing from 
8.2.3 that needs to be folded in is Route header processing. More below.

> 
> Next, if it is necessary to distinguish them, the criteria currently  in 
> the draft won't work. You can have out-of-dialog
> requests show up with Route headers fields.

Correct. As a side note there is a lot more to say on the concept of 
initial requests with Route headers. I think it has countless 
applications, but its a whole other discussion.

So, I need to take the Route header field discussion and put it into 
8.2.1 and that should work.

> 
> The only difference in behavior that I can back out of the current  text 
> (did I miss something?) is dealing with the situation
> where there is more than one contact currently bound to the GRUU.  8.2.1 
> says to use the most recent, 8.2.3 says to
> pick arbitrarily. To the implementer, this is going to appear arcane  at 
> best.

Right. I can't think of a reason why it needs to be different.

Thanks,
Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.                   600 Lanidex Plaza
Cisco Fellow                                   Parsippany, NJ 07054-2711
Cisco Systems
[email-masked]                              FAX:   (973) 952-5050
http://www.jdrosen.net                         PHONE: (973) 952-5000
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