H3C Technologies H3C SR8800 - Manual (Page 35)

23
Step Command Remarks
7. Configure the string to be
filled in the data field of each
UDP packet.
data-fill string
Optional.
By default, the string is the
hexadecimal number
00010203040506070809.
8. Specify the source port of UDP
packets.
source port port-number
Optional.
By default, no source port number
is specified.
9. Configure the source IP
address of UDP packets.
source ip ip-address
Optional.
By default, no source IP address is
specified.
The source IP address must be that
of an interface on the device and
the interface must be up;
otherwise, no probe packets can
be sent out.
10. Configure optional
parameters.
See “ Configuring optional
parameters for an NQA test
group
”
Optional.
Configuring voice tests
NOTE:
Do not perform voice tests on known ports, ports from 1 to 1023. Otherwise, the NQA test might fail or the
corresponding services of these ports might be unavailable.
Voice tests of an NQA test group are used to test voice over IP (VoIP) network status, and collect VoIP
network parameters so that users can adjust the network.
A voice test takes the following procedure:
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 voice packet that it receives and then sends it back to
the source.
3. Upon receiving the packet, the source calculates results, such as the delay jitter and one-way delay
based on the packet time stamps. The statistics reflect network performance.
Voice test result also includes the following parameters that reflect VoIP network performance:
• Calculated Planning Impairment Factor (ICPIF)—Measures impairment to voice quality in a VoIP
network. It is decided by packet loss and delay. A higher value represents a lower service quality.
• Mean Opinion Scores (MOS)—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 for voice quality, which should be taken into
consideration. For users with higher tolerance for 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 both the objective and subjective factors are considered
when you evaluate the voice quality.