Subject: [Sip] Outbound and GRUU,

From: [email-masked]
Date: Wed, 08 Mar 2006 18:51:27 +0100

Cullen and Rohan,

Could you provide explanations on relation between Outbound and GRUU.
In fact, I didn't follow whole the threads concerning the Outbound 
draft, perhaps it may explain my question.
However, could you answer the following points:
In my understanding, GRUU is useful when an AOR may be registered 
simultaneously on multiple UA instances.
However, the scope (and requirements) from Outbound seem different.
So, what are the motivations for making outbound fully dependent from GRUU?
For instance, in my opinion, a user registered on a natted UA could use 
outbound (and thus have a persistent connection with its proxy) without 
having an instance ID.
Why is it mandatory for a UA to have an Instance ID (as explained in 
section 4.1) for outbound?

Thanks for your help.

Thomas LEVY

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From: "Dale R. Worley" <[email-masked]>
Date: Wed, 08 Mar 2006 14:50:58 -0500

> simultaneously on multiple UA instances.

GRUU can be useful even when an AOR is registered to only one UA.  GRUU
is needed any time that the actual contact URI of the UA is not globally
routable.  When contact URIs are not globally routable, without GRUU,
native SIP-based call control can't be made to work.  So in any
situation where you are discussing outbound/STUN/ICE/etc., you can
assume that UAs are using GRUU.

Dale

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From: Rohan Mahy <[email-masked]>
Date: Wed, 8 Mar 2006 15:11:04 -0800 (PST)

Hi Thomas,

The instance ID is required so that the proxy can tell it is dealing with
the same UA instance.  It doesn't matter if in a real deployment you might
only have one instance.  Remember that with outbound you are encouraged to
use multiple flows, all with the same instance id.

Outbound solves a general problem.  Even if an instance id might not be
needed in a specific use case, it does not hurt anything to include it.

hope this helps.
thanks,
-rohan

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From: [email-masked]
Date: Thu, 9 Mar 2006 10:29:29 +0530

Hi Thomas,

The instance-id is mandatory because it identifies a specific device to which the message should be routed. There can be multiple connections to a device, hence to identify a connection the flow-id comes into effect. But, now the question is GRUU can be bounded to only one contact i.e. AOR/contact pair. Hence, the outer world can reach GRUU, i.e. one contact of a device, i.e. only one connection. In this case we wouldn't require the flow-id parameter. Only, the instance-id would be sufficient to route the call based on the instance-id.

Regards,

--Vikram.

[email-masked]

[email-masked]

03/08/2006 11:21 PM

To

[email-masked], [email-masked]

cc

[email-masked]

Subject

[Sip] Outbound and GRUU,

Cullen and Rohan,

having an instance ID.

Thanks for your help.

Thomas LEVY

*********************** FSS-Unclassified ***********************

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From: Cullen Jennings <[email-masked]>
Date: Thu, 09 Mar 2006 16:55:41 -0800

The latest version of outbound no longer depends on GRUU.

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From: [email-masked]
Date: Fri, 10 Mar 2006 09:13:37 +0100

You are right concenrning GRUU.
But, for the Outbound draft, the Contact is not used for routing a 
message to the UA. So, there should be no need for the Contact to be 
globally routable.

Thomas

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From: [email-masked]
Date: Fri, 10 Mar 2006 09:25:19 +0100

Hi Rohan,

You could still have multiple flows without using an instance id.
In fact, i think that the current version of the draft is confusing 
because a reader may believe that the isntance id is used for routing 
the messages to the UA.
My opinion is that it could help understanding the Outbound solution is 
there were 2 alternative solutions described in the document:
One solution without instance id and GRUU (applicable only for AOR with 
a single instance)
The full (actual) solution with instance id and GRUU (applicable in all 
the other cases)

Any comment about that?

Thomas

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From: Rohan Mahy <[email-masked]>
Date: Fri, 10 Mar 2006 08:02:25 -0800

Hi Thomas,

FYI: The latest outbound draft does not depend on GRUU.

Sorry, but there is no good reason to introduce a second solution.  The 
first solution is general and the second one is fully covered by the 
first.  The outbound draft is already long enough, and creating and 
using an instance-id is not a burden.  Generating one from your MAC 
address takes less than lines of code.  Then you just include it in 
your registers.

thanks,
-rohan

On Mar 10, 2006, at 0:25, [email-masked] wrote:
> My opinion is that it could help understanding the Outbound solution 
> is there were 2 alternative solutions described in the document:
> One solution without instance id and GRUU (applicable only for AOR 
> with a single instance)
> The full (actual) solution with instance id and GRUU (applicable in 
> all the other cases)
>
> Any comment about that?
>
> Thomas
> Rohan Mahy a écrit :
>
>> Hi Thomas,
>>

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From: Jonathan Rosenberg <[email-masked]>
Date: Mon, 13 Mar 2006 12:37:48 -0500

> You could still have multiple flows without using an instance id.

I dont see how. You need a unique way to know that these are two flows 
to the same instance, and thus, you only need to use one of the two 
contacts that have been registered.

-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
http://www.cisco.com

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From: Shida Schubert <[email-masked]>
Date: Fri, 17 Mar 2006 12:47:14 -0800

Hi Rohan;

 Actually I find this really confusing. And I do apologized if my 
question was answered
in last couple of days as I lost mails from the last few days.

 GRUU's example shows the GRUU URI as
 [email-masked];opaque={instance-id}.
 
 The way outbound is indicating a global routable address with instance 
mapping
information is
 [email-masked];sip.instance={instance-id}.

 *Although the example is for REGISTER/200 OK, section 4.1 specifies
   for UA to include the "+sip.instance" with SHOULD strength.

 I might be looking over something, or it could simply be my
ignorance but they both seem to address the property GRUU is trying to 
satisfy.

 Although with GRUU you could generate the user part and
allows for an address with an anonymous characteristic and
globally routable at the same time.

 Considering there is a need to support the handling and usage of the
instance id(or something equivalent that identifies the instance) on both
Proxy and UA in almost equivalent fashion, I don't understand why
you made the outbound independent of gruu?

 Regards
  Shida Schubert

Rohan Mahy wrote:
> Sorry, but there is no good reason to introduce a second solution.  
> The first solution is general and the second one is fully covered by 
> the first.  The outbound draft is already long enough, and creating 
> and using an instance-id is not a burden.  Generating one from your 
> MAC address takes less than lines of code.  Then you just include it 
> in your registers.
>
> thanks,
> -rohan
>