Subject: [Sip] REGISTER requests via NAT

From: "Vladimir A. Butenko" <[email-masked]>
Date: Fri, 07 Nov 2003 00:03:28 -0800

Excuse me if this topic has been already discussed, I have not found an 
answer in the list archive.

The situation: an organization with 2 offices, each running its own NAT'ed 
network, with a SIP server installed on each NAT gateway. The SIP servers 
insert the Record-Route headers for all requests coming to and from their 
LANs, and they also do media stream proxing: the Record-Route mechanism 
allows [email-masked] to exchange SIP messages and to establish calls 
with any [email-masked].

Now, the organization decides to register users of these 2 (or more) 
networks within one domain, so employees moving back and force between 
offices can be addressed by their name, [email-masked]. The company.com 
SIP registrar is installed, let's say, "outside" both LANs.

The SIP servers in each office properly redirect the REGISTER requests to 
that company.com server. But the Contact: header fields, obviously, contain 
the internal LAN addresses of those users.

As the RFC3261 explicitly specifies that any Record-Route information in 
REGISTER requests should be ignored, is there any other, "legal" way to 
"attach" the routing information to those requests, so it is stored by the 
registrar and all SIP requests made to [email-masked] from a different LAN 
(coming to the registrar proxy) will be routed correctly?

Sincerely,
Vladimir

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---

From: Jonathan Rosenberg <[email-masked]>
Date: Sat, 08 Nov 2003 03:03:10 -0500

See the Path header extension:
http://www.ietf.org/rfc/rfc3327.txt

-Jonathan R.

Vladimir A. Butenko wrote:

> The situation: an organization with 2 offices, each running its own 
> NAT'ed network, with a SIP server installed on each NAT gateway. The SIP 
> servers insert the Record-Route headers for all requests coming to and 
> from their LANs, and they also do media stream proxing: the Record-Route 
> mechanism allows [email-masked] to exchange SIP messages and to 
> establish calls with any [email-masked].
> 
> offices can be addressed by their name, [email-masked]. The 
> company.com SIP registrar is installed, let's say, "outside" both LANs.
> 
> The SIP servers in each office properly redirect the REGISTER requests 
> to that company.com server. But the Contact: header fields, obviously, 
> contain the internal LAN addresses of those users.
> 
> "attach" the routing information to those requests, so it is stored by 
> the registrar and all SIP requests made to [email-masked] from a 
> different LAN (coming to the registrar proxy) will be routed correctly?
> 
> Sincerely,
> Vladimir
> 

-- 
Jonathan D. Rosenberg, Ph.D.                600 Lanidex Plaza
Chief Technology Officer                    Parsippany, NJ 07054-2711
dynamicsoft
[email-masked]                     FAX:   (973) 952-5050
http://www.jdrosen.net                      PHONE: (973) 952-5000
http://www.dynamicsoft.com

---

From: "Vladimir A. Butenko" <[email-masked]>
Date: Sat, 08 Nov 2003 14:33:49 -0800

On Sat, 08 Nov 2003 03:03:10 -0500
> http://www.ietf.org/rfc/rfc3327.txt

Thank you very much, that's exactly whay I was looking for. Please forgive 
my ignorance :-(.

Sincerely,
Vladimir