ARQ/ACF/ARJ between Gatekeepers?

Chris Wayman Purvis cwp at ISDN-COMMS.CO.UK
Fri Feb 2 13:19:40 EST 2001


Admission control works between gatekeepers and entities that are registered
with them.  Conceptually no entity is permitted to be in more than one zone
(maybe a mistake - the opposite philosophy is used in SIP).  So it can't make
sense for one gatekeeper to register with another.

What's the problem with receiving calls from outside of the gatekeeper's zone?
You have the simple decision in a gatekeeper in this case of whether to allow
the receiving endpoint to accept a call from outside of the zone.  If you have
security problems you could insist on the calling endpoint's gatekeeper and the
destination gatekeeper routing call-signalling.  Then all you have to do is
configure a (potentially small) number of gatekeepers from which calls will be

It's calls within the gatekeeper's zone that are the difficult case!


Frank Derks wrote:
> Dear all,
> since the first version of H.323, the call signalling procedures have
> been explained through a series of examples. Although examples do help
> to get the idea on how things should work, they remain examples and
> are therefore (usually) incomplete.
> Take the example from Figure2/H.323v2 (or Figure 40/H.323v4): GK1 sends
> the SETUP message without first initiating the admission control procedure.
> If GK2 expects the admission control procedure to take place prior to
> the call setup, then this will fail unless GK2 makes an exception for
> certain "EPs" (GK1 in this case) to place calls without an admission
> control procedure.
> Are there any visions on this scenario?
> Frank
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Dr Chris Purvis -- Development Manager
ISDN Communications Ltd, The Stable Block, Ronans, Chavey Down Road
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