Subject: RE: Jerome's questions

From: [email-masked] (Igor Faynberg)
Date: Thu, 5 Nov 1998 12:29:34 -0500

Jerome Privat wrote:

>Some questions about <draft-ietf-pint-profile-00.txt>:

Very valid questions!

>
>1) I'm still not completly clear about what happens at the IP-SCN
>interface. What is the link between the PINT GW and the Service Control
>Gateway Function (SCGF as defined by ITU-SG11)? Is it an IP link or not?
>If the PINT protocol terminates at the PINT GW, what is the IP protocol
>used between the PINT GW and the SCGF?
>Or is the PINT GW colocated with the SCGF?
>

A good observation. These two interfaces are actually two because of the
perception that a neutral territory is necessary to lie between the IETF
and ITU-T domains. I am sure, this will dissapear soon (as has, for example,
the neutral land separating the Hungarian and Austrian borders).

Technically, however, in the ITU-T picture, the entities you mention are
"functions" (i.e., objects) rather than physical entities. The interfaces
among "functions" are "logical" (cf. Q.1204) rather than physical. Two
objects, for example, can reside in the same machine thus making the
issue of using any network protocol for communications between them moot.
(By the way, a similar functional rather than physical decomposition is
under the discussion on the device control list.) This has been traditional
and actually very useful ITU-T methodology: a) define functions, b) define
"information flows" among them, and c) map the information into protocol.

Now, the physical mapping has not yet been decided in SG 11, so what I am
to write here should be taken only as my own assessment of the situation.
I believe that the prevailing opinion is that no protocol is to be
defined between the PINT GW and SCGF, and that for all practial purposes
they would be--as you surmised--colocated. (In most implementations, Service
Control Points (SCPs) are UNIX machines, so the IP interface is a piece of
cake.) My opinion is based on the discussions with the SG 11 colleagues, and 
I invite those who disagree to voice their observations.

>2) How can a user be prevented from requesting a phone call to a number
>different from his actual phone number? Will PINT interact with AAA
>protocols to do that?
>

Another acute issue.  Steve Belloving has made a presentation at the last
AAA BOF on PINT needs, where he pointed out that the authentication is
the most essential thing.  I think this issue should be addressed at the
Orlando meeting. (Jerome, if this thing slips through the cracks, please
remind us to address it!)

>3) When the "To:" field contains an "email-like" address (e.g.
>[email-masked]) rather than a phone number, where is the
>translation to a GSTN number done? In SIP, when the INVITE arrives to a
>SIP server, the SIP server performs a lookup in a location database.
>Does a PINT server acts similarly?
>

Yes, I believe it has been agreed that the PINT URLs will be resolved at 
the PINT server.

Igor

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