Subject: Re: [Sip] updated GRUU spec

From: Jonathan Rosenberg <[email-masked]>
Date: Thu, 07 Jul 2005 01:43:07 -0400

sorry for the delay in responding Tom, and thanks for the comment. 
Response below.

Tom Taylor wrote:

> Minor comment on the GRUU spec.  At the beginning of section 8.4.1, the 
> procedure reads:
> 
> "... the proxy MUST check if the Request URI is a GRUU created by that 
> domain.
> 
> 
>   "If the GRUU does not exist within the domain, the proxy MUST generate
>   a 404 (Not Found) response to the request."
> 
> I'd suggest that "GRUU" in that last paragraph be changed to "Request 
> URI", since the proxy doesn't, absent a GRID parameter, know that it is 
> dealing with a GRUU.
> 

Actually, thats not right - it can know. It depends on the gruu 
construction algorithm. This actually relates to an open issue I raised 
at the last IETF - how the proxy knows to send a 404 vs. a 480.

Here is the full text of the first two paragraphs of this section:

8.4.1  Request Targeting

    When a proxy server receives a request, and the proxy owns the domain
    in the Request URI, and the proxy is supposed to access a Location
    Service in order to compute request targets (as specified in Section
    16.5 of RFC 3261 [1]), the proxy MUST check if the Request URI is a
    GRUU created by that domain.

    If the GRUU does not exist within the domain, the proxy MUST generate
    a 404 (Not Found) response to the request.

I'd suggest adding the following sentence to the end of the first paragraph:

"If the Request-URI is not within the domain of the proxy, the proxy 
follows the procedures in RFC 3261 and rejects the request. If the 
Request URI is within the domain of the proxy, and the proxy knows of 
the resource, but it is not a GRUU, processing is outside of the scope 
of this specification. If the request URI is within the domain of the 
proxy, and the URI has been constructed by the domain such that the 
proxy is able to determine that it has the form of a GRUU for an AOR 
that is unknown within the domain, the proxy rejects the request with a 
404. If the request URI is within the domain of the proxy, and the URI 
has been constructed by the domain such that the proxy is able to 
determine that it has the form of a GRUU for an AOR that known within 
the domain, but the instance ID is unknown, the proxy SHOULD generate a 
480."

This makes things much more specific, and also provides an algorithm for 
sending a 404 vs. a 480 that is readily realizable.

-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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