Re: XDD package H.248.16

H.248.16 clause 5.2 specifically talks about an unmatched digit event in the
"possible values" text of the Unmatched Event Parameter.  It then calls out
that it is also known as an "extra digit."

Step 5 deals with what to do with the digit string when you have a match to
one candidate sequence or a mismatch to all candidates.  In the base
protocol, the text specifically mandates that the digit that caused all
candidates to mismatch is removed from the dial string.  It then further
indicates that the digit so removed may be acted upon in a number of ways --
and that the completion event can specify that behavior.  This removed digit
is the "extra digit".

Actually, I misspoke earlier when I stated what the behavior would be...
that is what I get for speaking about something I haven't looked at in a
couple years without reviewing it.  The behavior can actually be quite a bit
more complicated than I had described.

The Extra Digit Disposition Parameter tells the MG what to do with the digit
that causes a mismatch: if xdd is on, the "extra digit" is discarded.  It is
not reported to the MGC, and it is not buffered for later matching.  This is
explicit.

If xdd is off, then the digit is acted upon based upon which matching
procedures are used. In the enhanced matching procedures, the "extra digit"
is not removed from the dial string, so it is reported as part of the
digitstring in the completion event.  In the base matching procedures, there
are actually a number of factors that then determine what is done with the
digit.  These include EventBufferControl, the Buffer Control Parameter in
the xdd package, and what the contents of the next Events Descriptor are.
In the case where EventBufferControl is set to LockStep, the EventBuffer
Descriptor contents also become relevant.

Digit collection is an inherently complex task, and how one constructs their
digitmaps will have a large say in how the various parameters in the
protocol are set to achieve the particular goals of the dial plan.  Careful
thought should go into how the digitmap is constructed.  For MGs, all they
can do is follow the procedures for the completion event and digitmap as
specified by the MGC.

The bast thing to do to learn the procedures is to write some examples and
trace them through the procedures.  That is certainly how I figured out how
they should work when I was drafting H.248.16.

Kevin

  

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of
Meir Leshem
Sent: Tuesday, November 25, 2008 5:28 AM
To: Kevin Boyle; Eli Liluz; [email protected]
Subject: Re: [Megaco] XDD package H.248.16

Kevin,
In the description of the xdd parameter, in case of "off" state it is
defined that extra digit event is processed as indicated in step 5. In step
5 there is no reference to extra digit event, so it is not understood to us
what is the difference in the process of step 5 in the
2 cases (of "off" and "on"). Could you elaborate on that?

In addition the function of the 'bc' parameter is not clear.

Regards
---------------------------------------
Meir Leshem
Veraz Networks
--------------------------------------- 

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of
Kevin Boyle
Sent: Monday, November 24, 2008 7:40 PM
To: Eli Liluz; [email protected]
Subject: Re: [Megaco] XDD package H.248.16

It depends upon two factors:  The value of the xdd parameter, and the value
of the mp parameter.
 
If mp is enhanced, then the matching procedures of the xdd package are used.
In this case if xdd is on, then the extra digit that causes the mismatch is
discarded when reporting the digit string.  If the xdd parameter is off, the
extra digit is reported in the extra parameter when it is reported to the
MGC.
 
If mp is base, then the matching procedures of the base protocol are used.
If the xdd parameter is on, the extra digit is discarded.  If the xdd
parameter is off, the extra digit is buffered and awaits matching from
further digit collection commands.
 
Kevin


  _____  

From: [email protected] [mailto:[email protected]] On Behalf Of
Eli Liluz
Sent: Monday, November 24, 2008 4:30 AM
To: [email protected]
Subject: [Megaco] XDD package H.248.16



Hi, all.

I have a question regarding xdd (Extra Digit Disposition) parameter.

What is the difference in the DigitMap procedure in case xdd = on and xdd =
off?

Thank you,

Eli Liluz.



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