Subject: RE: [Megaco] Query about local control descriptor properties

From: "Tom-PT Taylor"<[email-masked]>
Date: Wed, 23 Jan 2002 16:23:59 -0500

The answer to your question is yes, (and I didn't receive Christian's
similar answer) but I am a bit worried about whether it is clear how this
works.  

(1) What it does it mean if ReserveValue is unspecified in a modified
descriptor?  I would think it means that ReserveValue reverts to default
(i.e. false).

(2) What does it mean if a package-defined property is no longer specified
in a modified descriptor?  The answer again could be reversion to default,
or it could mean that the property is absent, or it could mean that the
property is present but its value is undefined.  Let's look at the
implications of these three alternatives.

(a) If a package-defined property is dropped from LocalControl, it takes on
the default value specified by the package or provisioned in the MG.  The
implicit assumption is that the termination continues to support the
package.  The question in my mind is how long package support continues.  It
seems to me that, while some packages may be supported for the entire life
of a termination, others may apply only during a single call and will have
unexpected effects if they persist beyond that call.  What do other people
think about this?

(b) The dropped property is no longer present on the termination.  To
support this interpretation we would need to say for every property that the
MG tracks its presence/absence as well as its value if present.  This
approach says nothing about whether we assume that the package continues to
be supported on the termination.

(c) The dropped property is present but its value is undefined.  I find this
unappealing.  Like (a), it implies continued support of the parent package,
but doesn't have the advantage of a consistent story for physical
terminations passing to and from the NULL context.

So: anyone else want to tackle this?  

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
Sent: Tuesday, January 22, 2002 8:44 AM
To: [email-masked]'
Subject: [Megaco] Query about local control descriptor properties

Hi Tom & list,

RFC 3015 Section 7.1.7 LocalControl Descriptor mentions:

"If the MGC wishes to delete some information from the existing descriptor,
it
merely resends the
   descriptor (in a Modify command) with the unwanted information stripped
out."

Does the "unwanted information" refer to the properties which the MGC no
more
requires to be set on the termination......

Please reply back...

Thanks,
Kapil Nayar

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---

From: Christian Groves <[email-masked]>
Date: Thu, 24 Jan 2002 15:05:53 +1100

G'Day Tom,

I think the easiest reply is that:
o In general reserveValue, reserveGroup and streammode return to default
as the these cannot disappear from a termination. 
o For package-defined properties the property is removed/absent. a)
below can't work because not every property has a default. It then leads
to c) where the value is unknown and this is not desirable.

Regards,
Christian

> descriptor?  I would think it means that ReserveValue reverts to default

[CHG]

---

From: Christian Groves <[email-masked]>
Date: Thu, 24 Jan 2002 15:05:53 +1100

G'Day Tom,

Regards,
Christian

[CHG]