Subject: [SIP] SIP registration draft - routing via home network

From: [email-masked]
Date: Wed, 8 Nov 2000 17:40:33 +0200

I have a question regarding draft-schulzrinne-sip-register-00. In the draft
it says:
--
5 Home Services while in Visited Network
   For some applications, the user would like to employ services of the
   home network while generating outbound requests in the visited
   network.  The visiting UA needs to detect that it is in a foreign
   network and insert a Route header pointing to its home proxy server.
--
I guess this would be another use for Route header within the initial INVITE
and would be "loose" source-routing as has been discussed in some other
threads. However, how does the UA learn about it's home proxy server? Static
configuration works well if there is a single proxy address always to be
used. But in some cases the home network may assign "serving" proxies
dynamically for registering users - even based on user's service control
needs. In this case 200 OK for REGISTER would need to carry information
about the proxy, right? Should this be done by using Record-Route in
REGISTER & 200 or by some other means? 

Regards,
	Markus

> -----Original Message-----
> From: EXT Henning Schulzrinne [mailto:[email-masked]]
> Sent: 06 October, 2000 18:03
> To: [email-masked]
> Subject: [SIP] New draft on SIP registration
> 
> 
> I've written a quick draft on some of the issues related to how to do
> SIP registration when "visiting" networks. I would appreciate 
> feedback.
> The draft does not propose new SIP extensions, except for a possible
> Digest parameter to increase registration security.
> 
> The draft is
> http://www.ietf.org/internet-drafts/draft-schulzrinne-sip-regi
> ster-00.txt
> -- 
> Henning Schulzrinne   http://www.cs.columbia.edu/~hgs
> 
> _______________________________________________
> SIP mailing list
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> http://lists.bell-labs.com/mailman/listinfo/sip
> 

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---

From: "Henning G. Schulzrinne" <[email-masked]>
Date: Wed, 08 Nov 2000 16:59:10 -0500

I would like to avoid configuration as much as possible, as every
configuration option increases complexity. Thus, 'home' is unambiguously
defined by the user's From address. The server at that address can then
forward the request as needed. I would be curious why this is not
sufficient, as it is the same principle used for incoming calls.

We may be submitting a draft on general UA configuration soon; it might
be appropriate to include this there.

Also, with the discussion about Route headers, something like

Route: sip:[email-masked] ;at=home.com

would avoid problems on URL content (or maddr).