[SIPForum-techwg] Pseudo Registration vs Virtual Registration

Thu Feb 19 10:36:34 EST 2009

John,
 
See DM>> below
 
________________________________

From: ext Elwell, John [mailto:john.elwell at siemens.com] 
Sent: Thursday, February 19, 2009 9:21 AM
To: Middleton, David (NSN - US/Boca Raton); ext Francois Audet; Bernard
Aboba; hkaplan at acmepacket.com; sbharrat at sonusnet.com
Cc: techwg at sipforum.org
Subject: RE: [SIPForum-techwg] Pseudo Registration vs Virtual
Registration


David,


________________________________

	From: Middleton, David (NSN - US/Boca Raton)
[mailto:david.middleton at nsn.com] 
	Sent: 18 February 2009 20:54
	To: ext Francois Audet; Bernard Aboba; hkaplan at acmepacket.com;
sbharrat at sonusnet.com; Elwell, John
	Cc: techwg at sipforum.org
	Subject: RE: [SIPForum-techwg] Pseudo Registration vs Virtual
Registration
	
	
	Consideration should be given to PBXs without a unique domain
name.  In that case, the only domain name available is that of the
service provider.  Is the expectation that the SIP-PBX would be required
to accept this domain name?  If so, this should be specifically
required.
	[JRE] This is already covered in section 9. It also allows the
enterprise to use a sub-domain of the SP domain. 
	 
	DM>> While I agree that section 9 addresses the use of domain
names and there is a comment from Spencer / Mark Stewart about using IP
Addresses, section 9 doesn't cover relational aspects.  By this I mean,
it doesn't say that these domain options are all valid but only one may
be used within SIP messages.   I don't believe this statement is
accurate (perhaps with the exception of when the service-provider domain
is used) but I state it to illustrate the lack of a firm requirement.
As the draft stands now, a Service Provider is free to use their own
domain even if the PBX has an own-domain or sub-domain because section 9
allows multiple options.  "Option 2" clarifies this for the R-URI in
requests towards the PBX.  Domains in other headers are underspecified
as well (due to the flexibility of section 9) but are not as contentous.
	 
	An alternative is to require that the host part of the R-URI be
populated using the host part of the registration contact binding for a
SIP-PBX operating in Registration Mode.  This allows IP Addresses or
domain names to be used and ensures that the service provider domain is
not used in the R-URI sent to the SIP-PBX.
	[JRE] This is more like the "option 2" that Francois was talking
about. If the enterprise does not have a domain name, presumably it
would have to populate the host part with an IP address. 
	 
	John 
	 

________________________________

	From: techwg-bounces at sipforum.org
[mailto:techwg-bounces at sipforum.org] On Behalf Of ext Francois Audet
	Sent: Wednesday, February 18, 2009 1:17 PM
	To: Bernard Aboba; hkaplan at acmepacket.com;
sbharrat at sonusnet.com; john.elwell at siemens.com
	Cc: techwg at sipforum.org
	Subject: Re: [SIPForum-techwg] Pseudo Registration vs Virtual
Registration
	
	
	Yes, that was exactly my conclusion: nobody is is pushing for 2.
Correct.
	 

________________________________

		From: Bernard Aboba [mailto:bernard_aboba at hotmail.com] 
		Sent: Wednesday, February 18, 2009 09:13
		To: Audet, Francois (SC100:3055);
hkaplan at acmepacket.com; sbharrat at sonusnet.com; john.elwell at siemens.com
		Cc: techwg at sipforum.org
		Subject: RE: [SIPForum-techwg] Pseudo Registration vs
Virtual Registration
		
		
		The point is that option 2 as you describe is not what
the traces show.  
		
		The traces show the Request URI not being replaced by
the Contact URI in the case where another line is called.  This is
option 1, not 2. 
		
		In other words -- the "option 1" you say people are
converging on, is actually the same as what the traces show.
		
		And nobody actually proposed Option 2 as you describe
it. 
		
		
________________________________

		Subject: RE: [SIPForum-techwg] Pseudo Registration vs
Virtual Registration
		Date: Wed, 18 Feb 2009 11:02:02 -0600
		From: audet at nortel.com
		To: HKaplan at acmepacket.com; bernard_aboba at hotmail.com;
sbharrat at sonusnet.com; john.elwell at siemens.com
		CC: techwg at sipforum.org
		
		
		Wow, you totally lost me here.
		 
		No, this is not what I meant at all.
		 
		Option 1 is the case where the R-Uri is not replaced by
the Contact, and Option is the case where it IS replaced by the Contact.
That's what I meant.
		 
		For Option 1, I don't really care if the domain in the
R-URI is a domain or an IP address. If we want to force it to be an IP
address, fine with me. I would have tought it could be either an IP
address or the domain of the service provider.


________________________________

			From: Hadriel Kaplan
[mailto:HKaplan at acmepacket.com] 
			Sent: Tuesday, February 17, 2009 18:32
			To: Audet, Francois (SC100:3055); Bernard Aboba;
sbharrat at sonusnet.com; Elwell, John
			Cc: techwg at sipforum.org
			Subject: RE: [SIPForum-techwg] Pseudo
Registration vs Virtual Registration
			
			
			I'm not sure I understand the distinction you're
making between 1 and 2.

			 
			The request-uri is NOT replaced with the
Registered Contact-URI today.  I've looked at Bernard's traces and they
are similar to the ones I have.  It's true that for the INVITE he shows
it happens to be the same as the registered contact-URI, purely because
he's calling the same line number that he registered.  But if you were
to call a different line number, the username would change and thus it
would not even look like the Registered contact-URI.  Ergo, we're not
replacing the req-uri with the registered contact-uri.

			 
			Are you thinking that in option (1), the host
portion of the req-uri is a domain name rather than an ip-address:port?
Where does every SMB get such a domain name?  And how does the SP learn
it?  (I must have missed some email in the hay stack)

			 
			-hadriel

			 
________________________________


			From: Francois Audet [mailto:audet at nortel.com] 
			Sent: Monday, February 16, 2009 7:32 PM
			To: Bernard Aboba; sbharrat at sonusnet.com;
Elwell, John; Hadriel Kaplan
			Cc: techwg at sipforum.org
			Subject: RE: [SIPForum-techwg] Pseudo
Registration vs Virtual Registration

			 
			I think there are two ways to see the
"registration":

			1.	A mechanism that allows a SIP-PBX to
provide a SP with the IP address of it's "proxy" function. In this
model, basically, the idea is that the Service Provider and Customer are
separate domains, and the same rules that apply in inter-domain RFC 3261
routing applies. I.e., the Request-URI isn't changed to a Contact. The
"pseudo-registration" is in fact not a real SIP Registration: it just
happens that the bits on wire look like one. 
			2.	A mechanism that allows a SIP-PBX to
mass-register a bunch of UAs. In this model, the virtual registration is
a short-hand that is functionally equivalent for having the SIP-PBX
forwards all the individual registrations one-by-one. But it does it "en
masse" instead. 

			1 is the way I had described it, and 2 is
Bernard's. Depending on which model we choose, we'll arrive at different
conclusions in what the content of the Request-URI should be.

			 
			1 allows a model where the "SIP-PBX" is a SIP
Proxy (even if in that case, the proxy would be doing an un-natural
act). 2 does not, and the implication is that the "SIP-PBX" must be a
B2BUA. I'm not sure if it really matters since one could say that if you
are really using an Enteprise SIP Proxy, you shouldn't be using this
pseudo-registration in the first place.

			 
			I'd like to get a sense of the group on that is
preferable, the "pseudo-registration" model, or the "virtual
registration" model.

			 
			They have been some suggestion on the list that
"nobody is really suggesting that we replace the R-URI with the
contact", but I'm not sure this is true. Certainly this "virtual
registration" proposal would point to that direction.

			 
			I don't care that much either way, but my
personal feeling is that the "pseudo-Registration" model is more
widespread and does not suffer from the problems of effectively forcing
support for Route header and probably History-Info for features like
Enteprise-based Voicemail.  I believe it would be more interoperable and
easier to deploy to go for the pseudo-registration model. Furthermore, I
believe evolving from the pseudo-registration model to normal DNS-based
SIP would be a lot easier (e.g., when a company growns enough to affort
it's own DNS domain).

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