Use of IRR by Gateways

Paul E. Jones paulej at CISCO.COM
Wed Mar 29 16:17:24 EST 2000


I have to disagree.  If I have a GK that sends an IRQ with a specific CRV,
it means that it wants call details about the call.  Why else would it send

With a CRV=0, it wants all call details.  This included the perCallInfo, as
well, and is important for the alternate Gatekeeper procedure (among other

So, why is the field OPTIONAL in the ASN.1?  Because if the GK queries for a
call that does not know about, it returns an IRR to the IRQ without any


----- Original Message -----
From: "Paul Long" <plong at SMITHMICRO.COM>
To: <ITU-SG16 at>
Sent: Wednesday, March 29, 2000 10:48 AM
Subject: Re: Use of IRR by Gateways

> Mohamed,
> Neither H.323 or H.225.0 actually require that an EP ever provide
> perCallInfo. For example, notice the passive tense and lack of "shall" in
> this passage, the closest we have to normative text on the subject:
> 7.15.1/H.323v3: "callReferenceValue - ...  If zero, this message is
> interpreted as a request for an IRR for each call the terminal is active
> on."
> Reports from the field indicate that many (most?) EPs don't ever encode
> perCallInfo (Smith Micro does) and conversely most (all?) GKs don't ever
> look at the field anyway. IMO, this field is therefore useless. My
> recommendation to you is to simply ignore that field. Apparently IRR is
> _only_ used as a heartbeat indication.
> BTW, this is an example of why it is important for contributors and
> to avoid using the passive tense in Recommendations. They should also be
> conscious of the verbs they use, e.g., "shall" is the ITU's only normative
> verb, "is" is not.
> Paul Long
> Smith Micro Software, Inc.
> -----Original Message-----
> From: Mohamed Mustafa [mailto:M.Mustafa at SDXPLC.COM]
> Sent: Wednesday, March 29, 2000 7:18 AM
> Subject: Use of IRR by Gateways
> Hi All,
> H.323 requires all endpoints to transmit an IRR message in response to
> an IRQ message from a Gatekeeper (or some other entity), and also to
> send unsolicited IRR messages to the Gatekeeper's RAS address at
> specific intervals if requested by the Gatekeeper in the ACF or RCF
> messages.
> As I understand it, an endpoint must provide the details of all active
> calls in a single IRR response if the callReferenceValue field in the
> IRQ is set to 0. This is clearly not possible if the endpoint supports
> thousands (or even hundreds!) of simultaneous calls. Can anyone provide
> any guidance on what to do in such a situation?
> Also, in the case of unsolicited IRR messages, I can't find anything
> which states that an endpoint must provide details of all active calls
> in each unsolicited IRR message. Therefore, an endpoint can either send
> a separate IRR message for each call, or it combine details of a number
> of calls (but not necessarily all) into each IRR message. Is my
> interpretation correct?
> Thanks,
> Mohamed

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