Subject: RE: [Sipping] [SIP] Call- IDs for same user

From: Michael Hammer <[email-masked]>
Date: Wed, 03 Oct 2001 12:05:49 -0400

Roy,

You are touching on some of the problems we had in T1P1 with distinguishing 
between a terminal registration and a personal registration.  In the end, 
it seemed the mobile carriers focused more on terminal registration, 
although the subscription (IMSI) registration in GSM enables it to migrate 
from terminal to terminal.

I would suspect that the two computers operate independently and the call 
IDs and Cseq will be independent.

By user do you mean UA?  From the registrars perspective these are probably 
two different presences (?) being registered.  I'm not sure if the 
registrar could deduce that user.host1@domain and user.host2@domain are the 
same user or not.  The naming convention could be implementation 
specific.  Is this a don't care?

What is your goal?

Mike

At 10:03 AM 10/3/2001 -0500, Sean Olson (EUS) wrote:

>-----Original Message-----
>From: Radhika [<mailto:[email-masked]>mailto:[email-masked]]
>Sent: Wednesday, October 03, 2001 6:19 AM
>To: [email-masked]
>Subject: [Sipping] [SIP] Call- IDs for same user
>
>Hello,
>
>In RFC 2543, it is mentioned that the same user issuing multiple REGISTER 
>requests should have the same call-id (atleast within the same boot cycle).
>
>Consider the following scenario :
>
>Computer1 (User A)                   Computer2 (User A)
>( Callid = 1)                        ( Callid 
>=2)
>  ----------------                    -----------------
>I                l                   l                 l
>I                l                   l                 l
>I                l                   l                 l
>I                l                   l                 l
>  ----------------                    ------------------
>Registrations performed from each computer
>
>Computer 1 = R11, R12
>Computer 2 = R21, R22
>
>Regarding the same I have the following queries:
>1) If the same user agent ( ie the same user ) logs in from 2 different 
>computers, 2 REGISTER requests will be sent  ( may or may not be 
>simultaneously ). In this case, should they have different call-ids ? (ie 
>Callid = 1)
>
>The situation you are talking about actually involves two separate user 
>agents and
>therefore separate call IDs for computer1 and computer2 are appropriate.
>
>2) Since multiple registrations are allowed from the same callid, the only 
>distinguishing criteria between registrations from same callid will be the 
>CSeq no. If a new registration is to be added by user A from Computer1, 
>then it will have a higher CSeq no.
>
>But, if an already existing registration ( R11 of Callid = 1) needs to be 
>refreshed before it expires, then a REGISTER request for the same needs to 
>be issued.
>
>Well, first computer1 and computer2 will use different call-IDs. Second,
>computer1 and computer2 will have different From: tags. The CSeq: space
>will be distinct between computer1 and computer2 because they have distinct
>call legs.
>
>How do I distinguish between a new registration for the same callid, and 
>registration renewal for an existing one?
>
>In general, you don't have to. If anyone needs to make a distinction, it 
>is the
>registrar. The registrar uses its internal state information about current 
>registrations
>to determine that a REGISTER is a re-registration or a fresh registration. 
>IMHO,
>tying the Call-ID to this state is a BAD idea.
>
>Can the CSeq for the original request and the renewal request be the same?
>
>No. A new request must also increment the CSeq:
>
>Thanks and regards,
>Radhika.
>
>Regards,
>Sean Olson

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---

From: "Radhika" <[email-masked]>
Date: Thu, 4 Oct 2001 10:15:27 +0530

Hello,

I am developing a Registrar, and my goal is to identify new registrations,
registrations indicating shift of domains, renewal of registrations etc.

However, how can I distinguish between registrations that are new, from
those that are renewed.

Thanks and Regards,
Radhika.

---

From: "Bob Penfield" <[email-masked]>
Date: Thu, 4 Oct 2001 08:16:47 -0400

Radhika,

As bis-04 states, the URI in the To header is the "address of record" for a
registration. That identifies the "user". The requirement for using the same
Call-ID is for the "client" which is not the same thing. Given that, I would
think you would have a set of registrations for a given user keyed by URI in
the "To" header. If you receive another registration from a different client
(different Call-ID), but the same To, it would be the same user. Then it
would be a matter of matching the Contact headers in the REGISTER with those
in the registration list. Contacts which match are updates to those
registrations for that user. Unmatched Contacts would be additional
registrations for that user. You would only delete a registration for a user
when it expires.

A given user may have multiple SIP devices (i.e. clients) which register
with the same registrar at the same time (e.g. office phone, home phone, and
mobile phone).

A client can remove all registrations by specifying "*" as the Contact and a
0 expiration. This brings up a couple of questions I have:

1) Does Contact:* with Expires:0 remove all registrations for the "user" or
all registrations for just that client (based on Call-ID)? I would think it
would be the user.

2) Does the 2xx response list all registrations for the "user" or for the
"client" based on the Call-ID? Again I think it would be for the user.

Anyone please correct me if I am wrong.

I hope that helps.

cheers,
(-:bob

Robert F. Penfield
Chief Software Architect
Acme Packet, Inc.
130 New Boston Street
Woburn, MA 01801
[email-masked]

----- Original Message -----
From: "Radhika" <[email-masked]>
To: "Sean Olson (EUS)" <[email-masked]>; "Michael Hammer"
<[email-masked]>
Cc: <[email-masked]>
Sent: Thursday, October 04, 2001 12:45 AM
Subject: Re: [Sipping] [SIP] Call- IDs for same user

> > >From: Radhika
[<mailto:[email-masked]>mailto:[email-masked]]

---

From: "Radhika" <[email-masked]>
Date: Thu, 4 Oct 2001 18:30:50 +0530

Hello Bob,

Yes, for registration expiry and for 2xx responses, even I think it is based
on user. But what about registration renewal?

Thanks and Regards,
Radhika

----- Original Message -----
From: Bob Penfield <[email-masked]>
To: Radhika <[email-masked]>
Cc: <[email-masked]>
Sent: Thursday, October 04, 2001 5:46 PM
Subject: Re: [Sipping] [SIP] Call- IDs for same user

> > > registrar could deduce that user.host1@domain and user.host2@domain
are
> > the
> > > >distinguishing criteria between registrations from same callid will
be
> > the
> > > >But, if an already existing registration ( R11 of Callid = 1) needs
to
> be
> > > >refreshed before it expires, then a REGISTER request for the same
needs
> > to