H.225 Annex G hierarchies

[Santo Wiryaman]

Dear Colleagues:

I completely agree with Mr. Roy that we should include a discussion in
Annex G on how zones within an Administrative domain can be arranged as
is described in APC-1385.

However, my version of APC-1375 titles Annex G as "Communication Between
Administrative Domains".  As currently defined in Annex G, an
Administrative Domains includes a "Border Element" and there is an
implied hierarchy structure between a border element and regular
gatekeepers (granted that this could be a degenerate form of hierarchy,
i.e. flat).

The proposal we brought to the table is how we could arrange these
Administrative Domains in a manner that would be scalable consistent with
Goal #2 as stated in Annex G.

Santo Wiryaman
Videoserver Inc.
swiryaman at videoserver.com
+1.781.505.2348
+1.781.505.2101 (fax)

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From:  Mailing list for parties associated with ITU-T Study Group 16
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Sent:  Thursday, July 23, 1998 8:50 AM
To:  ITU-SG16
Subject:  Re: H.225 Annex G topics

Hi Everyone:

This proposal of Videoserver suggests a specific implementation scheme
that
is known as "hierarchical (or centralized)" model. A hierarchical model
has
both advantages and disadvantages (we had many discussions on this
before).

However, Annex G does not impose any restriction how the system
organization
will look like. Consequently, the system organization can be
"non-hierarchical (or distributive)", "hierarchical (or centralized)", or
"hybrid (distributive + centralized)" as proposed in APC 1385, and can be
chosen depending what is best from an implementation point of view.

The important point is that a "zone" having a single gatekeeper (GK)
remains
the basic building block. A domain may consist of multiple zones. The
possible logical organizational relationship for communications between
the
multiple zones can be "distributive", "centralized", or "hybrid" as
proposed
in APC 1385. The fundamental questions are as follows:

*       Can we define the inter-GK communications protocol (IGCP) that
satisfies the requirements in "distributive", "centralized", and "hybrid"
system organizational environment?
*       Can we use the same RAS protocol that will provide the scalable
solution for both connection oriented and connectionless networking
environment considering the large-scale H.323 network? Or do we need the
extension of this RAS protocol?

Therefore, it is strongly suggested that the above points that are being
suggested in APC 1385 should also be included in the work scope of Annex
G.

Thanks and regards,

Radhika R. Roy
AT&T
Tel: (732) 949 8657
Fax: (732) 949 8569
Email: rrroy at att.com