H3C Technologies H3C SecPath F1000-E - Manual (Page 84)

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NOTE:
It is recommended not to perform an NQA UDP jitter test on known ports, namely, ports from 1 to 1023.
Otherwise, the NQA test will fail or the corresponding services of these ports will be unavailable.
A voice test is used to test voice over IP (VoIP) network status, and collect VoIP network parameters so that
users can adjust the network according the network status. The procedure of a voice test is as follows:
1. The source (NQA client) sends voice packets of G.711 A-law, G.711 μ-law or G.729 A-law
codec type at regular intervals to the destination (NQA server).
2. The destination affixes a time stamp to each packet that it receives and then sends it back to the
source.
3. Upon receiving the packets, the source calculates the delay jitter and delay by calculating the
difference between the interval for the destination to receive two successive packets and the
interval for the source to send these two successive packets, and thus the network status can be
analyzed.
The voice parameter values that indicate VoIP network status can also be calculated in a voice test,
including:
• Calculated Planning Impairment Factor (ICPIF): Measures attenuation of voice data in a network,
depending on packet loss and delay. A higher value represents a lower network quality.
• Mean Opinion Scores (MOS): Measures quality of a VoIP network. A MOS value can be evaluated
by using the ICPIF value, in the range 1 to 5. A higher value represents a higher quality of a VoIP
network.
The evaluation of voice quality depends on users’ tolerance to voice quality, which should be taken into
consideration. For users with higher tolerance to voice quality, use the advantage-factor command
to configure the advantage factor. When the system calculates the ICPIF value, this advantage factor is
subtracted to modify ICPIF and MOS values and thus both the objective and subjective factors are
considered when you evaluate the voice quality.
Configuration prerequisites
A voice test requires cooperation between the NQA server and the NQA client. Before a voice test, make
sure that the UDP listening function is configured on the NQA server. For the configuration of UDP
listening function, see Configuring the NQA Server .
Configuring a voice test
Follow these steps to configure a voice test:
To do… Use the command… Remarks
Enter system view system-view —
Enter NQA test group view
nqa entry admin-name
operation-tag
—
Configure the test type as voice
and enter test type view
type voice Required