Locating users

William Pimentel w-piment at UNIANDES.EDU.CO
Tue Sep 8 13:54:55 EDT 1998


I am glad that you have asked for some clarifications.

The whole point is that we are considering GK-to-GK communications in
multiple GK environment. Let there be any number of GKs to participate for
GK-to-GK communications depending on specific configurations. It can be as
simple as single GK (single zone) or multiple GKs consisting of multiple
zones and multiple (administrative)-domains.

Before going to details, I guess that most of the questions that you have
asked have been clarified by me on September 1, 1998, in response to Douglas
Clowes' questions.

AT&T's contribution is considering the RAS signaling messages only (NOT call
setup, media negotiation, or data packets). In response to Mr. Clowes'
questions (please see the details in the email sent on Sept 1), it has been
explained that, in H.323, a GK's  knowledge is limited to zone-level only
(no "notion" of network-level path as in the case of IP, ATM, FR, or other
networks). The proposal does not mandate what path will be followed by the
call setup, media negotiation, or data packets associated with the call.

Yes, AT&T's contribution, like other proposals, also separates between the
RAS signaling stage and the call signaling stage. So, the call signaling is
free to take any path as appropriate.

In addition to AT&T's contribution, Nokia's APC 1382 (S. Sengodan, Nokia,
"On the Use of Multicast Scope for Gatekeeper Discovery," APC 1382,
Q.11-14/16 Rapporteur Meeting, Cannes, France, June 8-11, 1998) will also
explain why additional fields are needed in signaling messages. The extra
fields are primarily needed to facilitate routing of the messages between
the GKs in multiple GK environment.

I like to point out that a service provider, in general,  can create a
variety of back-end services through intercepting signaling messages from
the appropriate entities (e.g., GKs) situated in the optimal locations as
needed if the signaling messages are allowed to pass through those entities.

I hope that the above explanations will clarify the things.


> ----------
> From:         Chris Purvis WVdevmt-WS[SMTP:cpurvis at MADGE.COM]
> Reply To:     Mailing list for parties associated with ITU-T Study Group
> 16
> Sent:         Monday, September 07, 1998 12:29 PM
> Subject:      Re: Annex G
> Radhika,
> In my view there is a fundamental difference between the scheme that you
> are proposing and the other contributions on inter-administrative-domain
> communication:
> Your proposal continues to expect all RAS, call setup, media negotiation
> and, (for all I know - it's not clear to me in your proposal), data
> packets
> associated with a call to follow a path through intermediate entities that
> are on the path that address resolution messages happened to take.
> All the other proposals I have seen preserve a separation between the
> resolution phase (where messages may indeed need to be sent to a number
> of different places), and the call signalling stage which follows a more
> direct route between endpoints.
> Your proposal requires the addition of extra fields to almost all RAS
> messages, and will generate a significant amount of extra call signalling
> traffic on the global network.
> I still fail to understand what the technical (or business) advantages of
> this extra propogation of messages are.  My impression was that the vast
> majority of the people on last Friday's conference call share my
> scepticism.
> Regards,
> Chris
> --
> Dr Chris Purvis - Senior Development Engineer, WAVE CC Software
> Madge Networks Ltd, Wexham Springs, Framewood Road, Wexham, Berks.
> Phone:+44 1753 661359  email: cpurvis at madge.com

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