Use of IRR by Gateways

Paul Long plong at SMITHMICRO.COM
Wed Mar 29 10:48:34 EST 2000


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

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 editors
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

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?


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