Subject: Re: [Sipping] GRUU Issue: who did I call?

From: Jonathan Rosenberg <[email-masked]>
Date: Tue, 01 Feb 2005 00:32:39 -0500

inline.

Dean Willis wrote:

> 
> On Jan 31, 2005, at 8:27 AM, Michael Procter wrote:
> 
>> Cullen Jennings wrote:
>>
>>> I read the whole thread and I think there is a very simple
>>> solution....
>>>
>>> The problem is that with the addition of GRUU  to SIP we have two
>>> addressable things - ones is a user (and addressed with AOR)
>>> and other is device (addressed with GRUU)
>>>
>>
>> Yes.  There is another part of the problem though, which is where
>> we want to make a call to someone and all we have is the GRUU.
>>
> 
> 
> One can't, by definition, always answer the question "Who does this GRUU 
> belong to?", because that GRUU might no longer belong to someone. The 
> AOR to GRUU binding is, to some extent, ephemeral, and by design is not 
> required to be invertable.

Folks keep saying this, but it aint so.

The GRUU draft says that the GRUU/AOR mapping is supposed to persist to 
the greatest extent possible for real systems. That means that it should 
be forever, but if the power goes out and the disks crash, well, these 
things happen.

So, please let us discount the cases where the GRUU has "expired".

-Jonathan R.

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

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---

From: Dean Willis <[email-masked]>
Date: Tue, 1 Feb 2005 10:58:45 -0600

>> One can't, by definition, always answer the question "Who does this 
>> GRUU belong to?", because that GRUU might no longer belong to 
>> someone. The AOR to GRUU binding is, to some extent, ephemeral, and 
>> by design is not required to be invertable.
>
> The GRUU draft says that the GRUU/AOR mapping is supposed to persist 
> to the greatest extent possible for real systems. That means that it 
> should be forever, but if the power goes out and the disks crash, 
> well, these things happen.
>

"Expired" is a politically correct euphemism for "dead". If the power 
goes out or the disk crashes, your GRUU is dead. If your GRUU is dead, 
you probably can't figure out who it pointed to by following it to that 
destination!

And as far as I can tell, the requirement for "anonymous GRUUs" is in 
conflict for a requirement that says that for any GRUU that the AOR 
associated with the GRUU could be identified by examination of the 
GRUU. Now, I suppose we could change what we're doing there . . .

--
Dean

---

From: Cullen Jennings <[email-masked]>
Date: Tue, 01 Feb 2005 09:19:17 -0800

> we want to make a call to someone and all we have is the GRUU.

Can you get specific about the cases where this *might* happen. I understand
the REFER is one. I'm in the 'if it hurts don't do it mode"