call clearing by GK

[Espen Skjæran]

Greetings,

I don't either see why a gatekeeper which wants total control of the calls
without routing them, would use pregrantedARQ.

And, I don't think this can be done foolproof without introducing more "special
cases".
If the gatekeeper will send a DRQ or BRQ to an endpoint in a call with
pregrantedARQ, it will not know what to populate
the CallIdentifier and CallReferenceValue fields with to identify the call
properly. These are given in the ARQ.
If the call is routed through the gatekeeper, it can pick out the call ID and
CRV from the SETUP etc messages,
but (at least) on the terminating side the CRV to use in RAS is totally
uncorrelated with the CRV in the call signalling messages, and thus cannot be
used directly.

We had a proposal this Monterey meeting to re-introduce some of the lacking
functionality with the bandwidth control and auto-sent IRR messages in
pregrantedARQ , which was APC-1542.

Espen

Chris Purvis wrote:

> Oops!
> Sorry about the blank response!  Let's try again!
>
> This isn't QUITE as simple a question as it looks.
> I'd recommend looking at it from the two separate points of view:
> >From the endpoint's point of view, I would say the answer is "yes" (as Ritu
> says).  A gatekeeper is allowed to send you a DRQ to clear the call.
> Depending on how the endpoint is written, though, this may not be trivial to
> achieve, since without pregranted ARQs it is reasonable for an endpoint to
> want to match up DRQs with individual ARQs.
>
> As a gatekeeper, though, I wonder why one would want to implement that.  For
> the gatekeeper to be aware of a call when using pregranted ARQs, it must be
> routing call signalling, so it can quite happily terminate the call by means
> of ReleaseComplete - which will NOT break poorly written endpoints.
>
> The related question is whether an endpoint sends a DRQ on "normal" call
> termination in these cases.  If the gatekeeper is routing call-signalling it
> is arguably unnecessary (ReleaseComplete clears the call); if not, then
> potentially the first the gatekeeper knows about the call is the DRQ at its
> end (not useful!)!  Note that H.323v2 section 8.5.2 assumes that ARQ has
> happened at the beginning of the call, so behaviour where this is absent
> (due to pregranted ARQ) is arguable.
>
> This leaves a question mark over the use of the other call-specific RAS
> message, BRQ.  Bandwidth issues with pregranted ARQs are discussed in both a
> contribution and a TD from the recent Monterey meeting (I forget the
> numbers).
>
> Regards,
> Chris
> --
> Dr Chris Purvis - Senior Development Engineer, WAVE CC Software
> Madge Networks Ltd, Wexham Springs, Framewood Road, Wexham, Berks.  ENGLAND
> Phone: +44 1753 661 359  email: cpurvis at madge.com
>
> > -----Original Message-----
> > From: rtgupta at hss.hns.com [mailto:rtgupta at hss.hns.com]
> > Sent: 09 March 1999 5:19
> > To: srini at trillium.com
> > Cc: h323implementors at imtc.org; ITU-SG16 at mailbag.cps.intel.com
> > Subject: Re: call clearing by GK
> >
> >
> > Hi srini,
> >        Gatekeeper can clear an ongoing call by sending DRQ to
> > an endpoint.
> > Refer to section 8.5.3, ITU-T H.323 recommendation.
> >
> > Thanks,
> > Ritu.
> > _____________________________________________________________________
> > Ritu Gupta                                     |       email:
> > rtgupta at hss.hns.com
> > Senior Software Engineer,           |
> > rtgupta at hotmail.com
> > Hughes Software Systems,                  |       phone:
> > 91-80-2286390/91/92(W)
> > Banglore, Karnataka                       |
> > 91-80-3374075(H)
> > INDIA.                                         |       Fax     :
> > 91-80-2286393
> > _____________________________________________________________________
> > Restlessness and discontent are the first necessities of progress.
> >
> > srini at trillium.com (Srinivasa Beereddy) on 03/09/99 05:29:43 AM
> >
> > Please respond to srini at trillium.com (Srinivasa Beereddy)
> >
> > To:   h323implementors at imtc.org, ITU-SG16 at mailbag.cps.intel.com
> > cc:
> > Subject:  call clearing by GK
> >
> > I have a question on call clearing by Gatekeeper. Can a
> > GateKeeper send DRQ
> > to clear the call in a preGrantedArq case?
> > thanks in advance.
> > Srini
> > Trillium Digital Systems, Inc.