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Mon Oct 27 13:28:44 EST 1997


The original proposal for that capability set had a "number of calls" field
per data rate. During one of the evening sessions it was argued that given
the complexity of gateway resources (e.g. DSP's for transcoding and the
varying call capacity based on 384 or 128 calls), that the number of calls
would not be included because the number of calls would be changing
dynamically and no matter what structure was chosen to represent the caps,
the race condition between the GK and the GW could not be fixed.

Instead, the capabilities simply notify the GK that the GW is willing to
accept calls of that rate. The GK is not told how many. When a GW runs out
of capacity (for whatever reason) for a particular call type it can send a
ResourcesAvailable 225 RAS message which no longer has that data rate
included.  When the GW is again available for calls of that rate, it sends
the message again with that rate included.

So for your questions, a gateway which can do calls at 384K or 128K  would
register with 64K and a multiplier of 2 and 384K with a multiplier of 1
assuming it is bonding itself. If at some point the number 2B calls
rendered it without the capability to accept a 384K call, it would send a
resourceAvailable message to the GK with only the 64K-2 capability
(assuming it could still accept that type of call)


>10 instances of H.320 dataRatesSupported indicating channel rates of 64K
and channel multipliers of 2,1 instance of H.320 dataRatesSupported with
channel rates of 128K and
channel multiplier of 10?

channelrate=64, multiplier 2 (No information on max number of calls)
channel rate=384, multiplier 1
The former isn't that scaleable for large systems with 100s of ports,
but does allow a gatekeeper to know that it might need two E.164 numbers
to make the connections.
As a side question, how do you signal that you have 10 384k channels
that can also be used as 30 128k channels?
Pete Cordell
BT Labs
E-Mail: pete.cordell at
Tel: +44 1473 646436
Fax: +44 1473 645499

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