Subject: [Megaco] Statistics reset by MG

From: Sundar Bettadahalli <[email-masked]>
Date: Wed, 04 May 2005 08:49:09 -0400

Hi,

Megaco RFC specifies that statistics are reset when a termination is
subtracted.

------------------------------------------------------------------------
7.1.15   Statistics descriptor

The Statistics Descriptor provides information describing the status
and usage of a Termination during its existence within a specific Context.
....

Statistics are reset when a Termination is Subtracted from a Context.
------------------------------------------------------------------------

Does this mean that Media Gateway "must not" reset statistics under any
other circumstances? Like possibly topology changes?

Following is an example when resetting statistics is useful.
We are maintaining a RTCPXR statistics history table per DS1.
Whenever a SCN termination stops receiving stream from a PDN
termination, this table will be updated with the RTCPXR statistics
of the PDN termination at that moment.

Consider a simple VOIP call with bothway topology between a SCN and PDN
termination. When topology between SCN and PDN termination changes
from bothway to isolate, history table will be updated. Say topology is
changed to bothway and then isolate again. Statistics maintained in PDN
termination will be collected and updated in the history table again.
Now as can be seen, there is an overlap of statistics in the two updates
to history table. This problem can be solved if we can reset the
statistics mantained in the PDN termination. But this means that the
statistics sent to MGC when audited will not be for the whole duration
of the PDN termination's existence in this context.

Hence, I would like to know if resetting statistics other than during
termination subtraction is a protocol violation.

Thanks in advance,
Sundar

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