Subject: [Geopriv] Re: [Sip] WGLC on draft-ietf-sip-location-conveyance

From: Hannes Tschofenig <[email-masked]>
Date: Wed, 07 Mar 2007 13:21:39 +0200

Hi all,

I would like to understand what the relationship between
http://www.ietf.org/internet-drafts/draft-ietf-geopriv-l7-lcp-ps-00.txt
and
http://www.ietf.org/internet-drafts/draft-marshall-geopriv-lbyr-requirements-00.txt
is.

Can someone help me?

Ciao
Hannes

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From: "Brian Rosen" <[email-masked]>
Date: Wed, 7 Mar 2007 07:46:29 -0500

I think -lbyr-requirements talks about any protocol that handles l-by-r.
SIP (via location conveyance) would be an example.  An L7 LCP may be another
example.  Who knows, we could have a DHCP option that could retrieve one.

L7 lcp talks about a location configuration protocol working at Layer 7.
That protocol could return a location value, or a reference.  There is
probably some opportunity to remove l-by-r language from lcp-ps and make
reference to lbyr-requirements.

Brian

> -----Original Message-----
> From: Hannes Tschofenig [mailto:[email-masked]]
> Sent: Wednesday, March 07, 2007 6:22 AM
> To: GEOPRIV
> Subject: [Geopriv] Re: [Sip] WGLC on draft-ietf-sip-location-conveyance
> 
> Hi all,
>

---

From: Richard Barnes <[email-masked]>
Date: Wed, 07 Mar 2007 08:20:42 -0500

> example.  Who knows, we could have a DHCP option that could retrieve one.

This is a fine point we should be clear on: -lbyr-requirements doesn't 
deal with protocols that carry LbyR, but rather with protocols that 
implement LbyR.  SIP conveyance is an example of the former, while a 
SIP/PRES dereference using SUBSCRIBE/NOTIFY is an example of the latter.

In general, I would say that an LCP is a mechanism for a device to 
acquire its location with no (or very little) a priori knowledge, while 
an LbyR system is a generic system for querying a server for location 
information (as described by a URI format and a dereference protocol).

As you say, the part of an L7LCP where the target queries an LIS and 
gets a location seems to similar to an LbyR system, although exactly how 
much is to be determined.  I do think it will be worthwhile, though, to 
compare the two documents.

Cheers,
--Richard

---

From: Hannes Tschofenig <[email-masked]>
Date: Sat, 10 Mar 2007 21:54:57 +0200

Hi Brian,

Brian Rosen wrote:
> SIP (via location conveyance) would be an example. 
I hope we are not working on a requirements document for the SIP 
Location Conveyance draft (which is also in WGLC).

>  An L7 LCP may be another
True.

> reference to lbyr-requirements.

The only requirements that we came up with in the GEOPRIV L7 LCP DT with 
respect to l-by-r are the following
(and they do not have anything in there that ties them specifically to a 
L7 protocol).

-----------

   The following requirements are placed on the location-by-reference
   approach:

   o  The reference MUST be valid for a limited amount of time.

   o  The reference MUST be hard to guess, i.e., it MUST contain a
      cryptographically random component.

   o  The reference MUST NOT contain any information that identifies the
      user, device or address of record

   o  The Location Recipient MUST be able to resolve the reference more
      than once (i.e., there is no implicit limit on the number of
      dereferencing actions).

   o  Possessing a reference to location information allows a Location
      Recipient to repeately obtain the latest information about the
      Target with the same granularity.

   o  The Target MUST be able to resolve the reference itself.

-----------

Ciao
Hannes