Subject: [Sip] RFC 3261: BUG or clarification is needed

From: "Orit Levin" <[email-masked]>
Date: Wed, 17 Nov 2004 13:37:21 -0800

Guys,
I would like to get a clarification on the properties of the Contact
header in requests and responses different from REGISTER.
Is there a common understanding, that a Contact header can contain any
valid SIP URI that, especially when used outside the original dialog,
needs to be resolved according to RFC 3263 (i.e. including the SRV
lookup) ?
 
I couldn't find any statement along these lines in any of the relevant
RFCs.
 
For example, in Redirect requests, we are reusing the Contact header in
order to point to an alternative destination which can have nothing in
common with the original domain.
 
Yet another example, the current GRUU draft is silent about the ability
of resolving GRUU using RFC 3263 procedures. From the draft:
"the GRUU MUST exhibit the following properties:

   o  The domain part of the URI is an IP address present on the public

      Internet, or, if it is a host name, exists in the global DNS and

      corresponds to an IP address present on the public Internet."

For the interoperability sake, I believe that it is very important to
file this clarification against RFC 3261 and also point to RFC 3263 for
GRUU properties/location procedures.
 
Thanks,
Orit.
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From: Paul Kyzivat <[email-masked]>
Date: Wed, 17 Nov 2004 17:48:59 -0500

Orit Levin wrote:
> needs to be resolved according to RFC 3263 (i.e. including the SRV lookup) ?

Yes.

> I couldn't find any statement along these lines in any of the relevant RFCs.

Why would any special statement be required? The address in the contact 
gets included in some message, and then the rules for how to resolve it 
are spelled out. It doesn't matter where it came from.

> common with the original domain.

BTW, in some contexts (such as 3xx) the contact addresses need not even 
be ones used by sip. You are allowed to redirect to an http uri if you like.

> of resolving GRUU using RFC 3263 procedures. >From the draft:

I think this requirement is implicit.

	Paul

> Thanks,
> Orit.
> 
> 
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>