Subject: [Megaco] Draft H.248.48: host information in statistics qhr/reports

From: "Schwarz Albrecht" <[email-masked]>
Date: Thu, 12 Jul 2007 17:17:35 +0200

Hi Geoff,

I was just trying to recall again, how the MG derives the host
information per statistics block.

			rtcpHrReportResult = host ";" host ";"
hexOctetSequence

The two basic scenarios are
A) Local MPs and
B) Remote MPs.

My understanding:
In case A:
*	Host_MP information:
Is just the host part of the local CNAME. There is one CNAME
used/assigned by a single H.248 MG.
*	Host_OP information:
The measured RTP flow is unambiguously identified by the SSRC & CNAME.
The CNAME valued may be extracted from RTCP reports with the same SSRC
value, i.e. typically from SR (or RR, XR, HR, etc) packets (because a
SDES packet is always part of such RTCP packets).

In case B:
*	Host_MP information:
It's the host part of the CNAME element, as carried in the SDES part of
the RTCP HR packet with the remote SSRC (used for HR).(?) It's the SSRC
of the MP.
*	Host_OP information:
I may derivce the SSRC of the OP from the RTCP HR Header sub-block, but
the CNAME of the OP? 

Geoff, I'm struggling with the last list item, the host_OP information
in case of collected, i.e. remotely generated measurements.
Is my understanding above correct?
Did I overlook sth.?

We may use the "X:Y;<data>" block of example 2 in H.248.48 for the
discussion. I may derivce host_X, but not host_Y information.
If this understanding is correct then a possible solution would be that
the MG U may get the CNAME information from Y by monitoring the RTCP
packets from Y (in Y-to-X direction). Right?

Thanks,
Albrecht

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