Fwd: Re: Signalling required SCN call bandwidth

Michele Bozier WVdevmt-WS mbozier at MADGE.COM
Wed Mar 11 11:44:16 EST 1998


All,

Apologies if you've already seen this email before.

So far, the only suggestion I've received is that no endpoints really use the
multirate info correctly and so MCUs/ gateway manufacturers have to have
knowledge of the type of H.320 call to make, based on the called number.

It strikes me that having the ability to at least signal the required
bandwidth for the call in the H.225 Setup message, even if you don't include
WAN specific call setup parameters such as bonding/H.221-aggregration/Hybrid
call, could be of value.

What does everyone else think?
Michele
----------------------------------------
Michele Bozier
Principal Development Engineer
Madge Networks, Wexham Springs, Framewood Rd, Wexham,
Slough SL3 6PJ, England
Tel: +44(0)1753 661331  Fax: +44(0)1753 661011
email:mbozier at madge.com

----------------------------------------
Hi all,

I have a question about how to signal a multiple 'B' channel SCN call from an
H.323 endpoint.

The bearer capability information element in standard Q.931 allows you to
signal a Multirate call and then specify the bandwidth (in multiples of
64Kbps) using the optional rate multiplier octet (octet # 4.1).  My question
is how do I signal an n * 'B' channel call from my H.323 endpoint, where the
channels are aggregated using H.221 framing or Bonding?

Reading the H.225 standard, the description of the Rate multiplier field
indicates that it 'shall' be present if the call is Multirate as per standard
Q.931.  It then goes on to say that:
'For a call originated from an H.323 endpoint, this SHALL be used to indicate
the bandwidth to be used for this call'.

Is this field only mandatory if I am doing Multirate, or is the intention
that it should be used to indicate the number of 'B' channels irrespective of
how the ISDN call is placed (Multirate,multi-H.221 or Bonded)?  (My
understanding of pure Q.931 is that it really only ought to be present in the
Multirate case).

If I can't use the rate multiplier octet in the non-Multirate case, is there
a standard way I can signal a 2 * B, or 6 * B channel call?

Thanks in advance for your help!

Michele Bozier




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