Subject: [Ecrit] Getting location behind NAT

From: "Eric Turcotte \(QC/EMC\)" <[email-masked]>
Date: Wed, 19 Apr 2006 21:29:16 -0400

Hi,
I was wondering how a UAC gets its location from a DHCP Server behind a
NAT. Is this addressed in the current GEO  RFC or CIVIC drafts?
http://tools.ietf.org/html?rfc=&draft=draft-ietf-geopriv-dhcp-civil-09&s
ubmit=Submit
http://tools.ietf.org/html/rfc3825
Thanks,
Eric.
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From: Hannes Tschofenig <[email-masked]>
Date: Thu, 20 Apr 2006 10:16:10 +0200

Hi Eric,

you raise an interesting question. Could you describe your deployment 
environment a little bit more. For example, are you talking about a DSL 
environment?

Ciao
Hannes

Eric Turcotte (QC/EMC) wrote:
> _http://tools.ietf.org/html?rfc=&draft=draft-ietf-geopriv-dhcp-civil-09&submit=Submit_ 
> <http://tools.ietf.org/html?rfc=&draft=draft-ietf-geopriv-dhcp-civil-09&submit=Submit> 
> 
> _http://tools.ietf.org/html/rfc3825_
> Thanks,
> Eric.
> 
> 
> ------------------------------------------------------------------------
>

---

From: "Francois D. Menard" <[email-masked]>
Date: Thu, 20 Apr 2006 07:40:22 -0400

Has anybody standardized the process of grabbing location from the outside
nat interface to regurgitate on the inside?  If the outside is PPPoE like on
DSL networks?

F. 

--
François D. Ménard
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-----Original Message-----
From: Hannes Tschofenig [mailto:[email-masked]] 
Sent: 20 avril 2006 04:16
To: Eric Turcotte (QC/EMC)
Cc: [email-masked]
Subject: Re: [Ecrit] Getting location behind NAT

Hi Eric,

Ciao
Hannes

Eric Turcotte (QC/EMC) wrote:
> Hi,
> I was wondering how a UAC gets its location from a DHCP Server behind 
> a NAT. Is this addressed in the current GEO  RFC or CIVIC drafts?
>

---

From: [email-masked]
Date: Thu, 20 Apr 2006 08:08:52 -0500 (CDT)

Lets walk through this, because I think you will find it works pretty well
with one exception:

A device, say a hard SIP Phone sits behind a NAT.  It has an internal
address.  The device makes a DHCP query to a DHCP server that sits beyond
the NAT.

The DHCP request is relayed by the NAT.  It changes the from IP address to
its external address.

The DHCP server gets the request, and processes it.  It returns the
location associated with the subscriber/user, whether it uses the MAC
address, the IP address, or a DHCP relay circuit ID to the external
address (which is the NAT).

The NAT gets the DHCP reply, changes the To address and relays the
response to the SIP Phone.

So, as long as its correct that all devices behind the NAT are at the same
location, it works.

The thing that doesn't work is if the NAT is not just a NAT, but a router,
which supplies DHCP service for all the clients behind the NAT.  Then, the
DHCP server that the phone is querying is not the extenal DHCP server, its
the one in the router.  It would have to know to ask for location from its
DHCP server (the external one) and relay that option to its internal
clients.

Brian