Subject: SIP Registrar+Redirect behaviour

From: Eric Tremblay <[email-masked]>
Date: Mon, 13 Jul 1998 12:22:47 -0400

I have a small question concerning the behaviour of a SIP
registrar&redirect server that receives a REGISTER request with no
Location header.  Where will the call be redirected when the registrar
receives an Invite?  The draft states that "future call control requests
will be directed to the network source address of the REGISTER request
(the via field), using the To address in the REGISTER request as the
Request-URI."  It makes no sense for the redirect server to copy the
"To" header (of the REGISTER request) in the "Location" Header of the
301/302 reply (unless there is something I'm missing ;) ).  

This works fine for a Proxy, but the redirect server won't know where to
redirect the call.  Should it returns "501 Not Implemented" when
receiving such a registration?  Should it try to build a valid SIP uri
from the Via and To header?

EricT

Eric Tremblay       | Mediatrix Telecom
Ingénieur Stagiaire | -----------------
email: [email-masked]
Tel: +1(819)829-8749 ext. 238
Web: www.mediatrix.com

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From: Jonathan Rosenberg <[email-masked]>
Date: Mon, 13 Jul 1998 14:10:24 -0400

> 301/302 reply (unless there is something I'm missing ;) ).

I see two possibilities. The Location header of the 301/302 reply can
contain the username from the To field of the Register, and the IP
address from the Via:

C->S REGISTER
To: [email-masked]
Via: 10.1.1.1

A->S INVITE joe

S->A 300
Location: [email-masked]

Alternately, if we allow for non-multicast IP addresses to be included
in the maddr field:

S->A 300
Location: [email-masked];maddr=10.1.1.1

In other words, the user@domain in the Location response is what was in
the To field of the REGISTER, and the IP address is included as a
parameter. If we do this, we might want to change the name from "maddr"
to "ipaddr".

-Jonathan R.
-- 
Jonathan D. Rosenberg                       Lucent Technologies
Member of Technical Staff                   101 Crawfords Corner Rd.
High Speed Networks Research                Holmdel, NJ 07733
FAX:   (732) 834-5379                       Rm. 4C-526
EMAIL: [email-masked]
URL: http://www.cs.columbia.edu/~jdrosen

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From: Henning Schulzrinne <[email-masked]>
Date: Mon, 13 Jul 1998 16:43:31 -0400

> contain the username from the To field of the Register, and the IP

That was the behavior I had in mind. It seems simplest and should cover
the common case. For more sophisticated cases, the server can always
include an explicit Location header.

-- 
Henning Schulzrinne   [email-masked]
Dept. of Comp. Sci.   ph  +1 212 939-7042
Columbia University   fax +1 212 666-0140
New York, NY 10027    http://www.cs.columbia.edu/~hgs

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From: Mark Handley <[email-masked]>
Date: Mon, 13 Jul 1998 17:26:30 -0400

>> > Location header.

In the interests of simplicity, shouldn't this simply be illegal and
generate "400 Bad Request"?

Mark