Chapter 19 Configuring telephones: IP telephones 137
PVQM - Proactive Voice Quality Monitoring
PVQM monitors and reports on call quality in process, not just after the end of the call. This enables more timely and accurate resolution of potential call quality problems, especially on more lengthy calls. A call quality threshold is set so that an exception is reported if the quality drops below a configurable value.
PVQM is fully supported on Phase 2 IP sets. Phase 1 IP sets support only the following PVQM metrics: packet loss, inter arrival jitter, and round trip delay.
The following path indicates where to set PVQM thresholds in Element Manager:
•Element Manager: Administration > Telephony Metrics > PVQM > Threshold Settings
Panel
The following is a description of the metrics:
•Packet Loss: Packet loss can be viewed as an extreme case of delay. There are a number of reasons that a packet could be lost in transit. If a network failure occurs, packets may be lost during the time that traffic is rerouted through alternate facilities.
•Inter Arrival Jitter: Packet jitter refers to a variable delay on a packet
•RTCP Round Trip Delay: Round trip delay is an important measurement of network performance.
•Listening R Factor: A direct measure of the call quality or transmission quality, and incorporates the effects of CODEC type, packet loss, discard, burstiness, delay etc. This metric describes the segment of the call that is carried over this RTP session.
There are two thresholds for PVQM metrics: Warning, and Unacceptable. A violation of the Warning threshold indicates that the voice quality is reduced but is still within an acceptable range. A violation of the Unacceptable threshold indicates a severe degradation in voice quality.
If an alarm is generated to report a threshold violation, additional information will be included in the alarm to tag the source of the alarm and provide other information that may be helpful in monitoring voice quality on the system and across the network.
For an explanation of the Metrics tab and the default PVQM threshold settings refer to the BCM 4.0 Administration Guide (N0060598).
