Subject: Re: [Sip] Another Comment on draft-audet-sip-sips-guidelines-03 w.r.t. telURI etc

From: Aki Niemi <[email-masked]>
Date: Wed, 25 Oct 2006 22:34:45 +0300

<lurk-mode-off />

ext Paul Kyzivat kirjoitti:
>> Refer the following from section 10.2.1 of 3261
>> "A SIP UA can choose to register telephone numbers (with the tel URL,
>> RFC 2806 [9]) or email addresses (with a mailto URL, RFC 2368 [32]) as
>> Contacts for an address-of-record, for example."
> 
> I have some sympathy for this. I think we get wound up thinking that the
> contacts being registered are in fact destinations belonging to the UAC
> doing the REGISTER. While this is usually the case, it need not always
> be the case.

I've seen SIP/3.0 mentioned here a few times, so here's my contribution
to that end.

I think it was a mistake to give REGISTER this dual meaning. i think we
are in fact talking about two very different functions.

1) LOGIN by which a UA connects to the system (using sip-outbound) for
being able to send requests outside (and having the system sign them
with SIP idnetity) and receive requests inbound.

2) ALIAS by which another agent, perhaps acting for the AOR in some
capacity, registers (ok, could be called REGISTER, too) another means of
contacting the principal that owns the SIP AoR.

Why I think these should be clearly separate methods is that the
authorization decisions and the routing logic associated with them are
vastly different.

Cheers,
Aki

<lurk-mode-on />

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---

From: Paul Kyzivat <[email-masked]>
Date: Wed, 25 Oct 2006 16:07:44 -0400

Aki,

I don't know whether to agree or disagree. You seem to be suggesting 
that *something* ought to be different in SIP/3.0 because we got it 
wrong in 2.0. But I'm not sure which part we got wrong. (I agree that it 
seems that *something* is wrong.)

Unfortunately, I don't think that now is the time to be talking about 
SIP/3.0. That would be a good way to ensure the total demise of SIP.

In the "if I were starting over I would do it differently" category, I 
have recently been thinking along somewhat similar lines. In particular 
I've been thinking that for NAT/FW, lack of certs, etc. (all sorts of 
things where the UA lacks capabilities it needs to fully participate) it 
would have been better for it to latch up to some "agent" that has all 
those things and can act on its behalf in all ways. This would be a 
B2BUA, and possibly a TURN server. Its would be something like an SBC or 
a P-CSCF, but it would work on behalf of the UA, not the "provider". 
 From the point of view of everybody else, this "agent" would be the UA.

That would leave the basic sip stuff more "pristine", and leave the 
fixups to this one relationship.

But that is just idle thought. I don't see how we can turn the clock back.

	Paul

---

From: Aki Niemi <[email-masked]>
Date: Wed, 25 Oct 2006 23:27:02 +0300

> From the point of view of everybody else, this "agent" would be the UA.

I think we're definitely headed that way already with outbound, identity
and others. I think it's mainly the NAT problematics that makes most UAs
unable to participate to the system unless they "login" at an agent and
use the same transport for all further communications.

> fixups to this one relationship.

Or perhaps another way to put it is that there are separate UNI and NNI
in SIP. Or c2s and s2s as XMPP puts it, I think.

Cheers,
Aki

---

From: "Francois Audet" <[email-masked]>
Date: Wed, 25 Oct 2006 16:56:31 -0500

> I think we're definitely headed that way already with 
> outbound, identity and others. I think it's mainly the NAT 
> problematics that makes most UAs unable to participate to the 
> system unless they "login" at an agent and use the same 
> transport for all further communications.

Agree.

> Or perhaps another way to put it is that there are separate 
> UNI and NNI in SIP. Or c2s and s2s as XMPP puts it, I think.

Outch...

---

From: "Francois Audet" <[email-masked]>
Date: Wed, 25 Oct 2006 17:03:34 -0500

> -----Original Message-----
> From: Paul Kyzivat [mailto:[email-masked]] 
> Sent: Wednesday, October 25, 2006 1:08 PM
> To: Aki Niemi
> Cc: [email-masked]
> Subject: Re: [Sip] Another Comment on 
> draft-audet-sip-sips-guidelines-03 w.r.t. telURI etc
> 
> Aki,
> 
> I don't know whether to agree or disagree. You seem to be 
> suggesting that *something* ought to be different in SIP/3.0 
> because we got it wrong in 2.0. But I'm not sure which part 
> we got wrong. (I agree that it seems that *something* is wrong.)
> 
> Unfortunately, I don't think that now is the time to be 
> talking about SIP/3.0. That would be a good way to ensure the 
> total demise of SIP.

The assumption/directiveve in the draft-audet-sip-sips-guidelines
document
is that we are NOT talking SIP 3.0, but the current RFC 3261,
potentially
with some corrections when absolutely necessary. It tought it was pretty
clear from Montreal that this is what we agreed to.

That's kind of what I'm saying in my reply to Dean.

If security was to be redone (with SIP 3.0 for example), I don't think 
we would define a secure URI scheme like sips for one thing. And I 
certainly don't think we would tie security to a single security 
mechanism (TLS or otherwise).