How Voice Quality Monitoring Works - Nortel Communication Server 1000E Maintenance Manual

How voice quality monitoring works

PVQM monitors voice quality by polling IP endpoints during and at the end
of a call to sample the following voice-quality metrics:
•
Latency - length of time, in seconds, for information to travel through
the network
•
Jitter - the variability in latency, in seconds
•
Packet Loss - number of packets lost during transmission, in
percentage
•
R-Value - measurement of listening R-Value using ITU E-Model.
R-Value maps to Mean Opinion Score (MOS).
The sampled metrics are compared to user-configured thresholds to
determine system performance. When sampled metrics exceed configured
thresholds, the system generates statistics.
For details about configuring metric thresholds, see
voice-quality metric thresholds" (page
The Signaling Server collect statistics for each metric to create a Quality
Detail Report (QDR). The QDR summarizes metric threshold violations
into one of the following categories:
•
Warning
•
Unacceptable
Each summarized QDR record is added to the IP Phone Zone Traffic
Report 16 (TFS016). The TFS016 report summarizes by zone the voice
quality over the reporting period to allow the administrator to view the
overall voice quality. For more information about TFS016, see Traffic
Measurement: Formats and Outputs Reference .
An SNMP alarm is generated when a voice quality metric threshold
exceeds Warning or Unacceptable status. For details about controlling
the number of SNMP alarms generated, see
alarm-notification levels" (page
Figure 52 "Voice quality monitoring flow diagram" (page 174)
PVQM within the Voice over IP (VoIP) system.
Nortel Communication Server 1000
Communication Server 1000E Maintenance
NN43041-700 04.01 4 June 2010
Copyright © 2004-2010 Nortel Networks. All Rights Reserved.
How voice quality monitoring works 173
"LD 117 Configure
175).
"LD 117 Configure zone
177).
illustrates