Configuring voice tests
![[IMPORTANT: ]](images/important.png) | IMPORTANT: 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 performs the following procedure:
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).
The destination affixes a time stamp to each voice packet that it receives and then sends it back to the source.
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 of 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, so objective and subjective factors are both considered when you evaluate voice quality.
Configuration prerequisites
Voice tests require cooperation between the NQA server and the NQA client. Before you start voice tests, configure a UDP listening service on the NQA server. For more information about UDP listening service configuration, see "."
Only one probe operation is performed in one voice test.
Configuration procedure
To configure voice tests:
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter NQA test group view. | nqa entry admin-name operation-tag | N/A |
3. Configure the test type as voice, and enter test type view. | type voice | N/A |
4. Configure the destination address of voice probe packets. | destination ip ip-address | By default, no destination IP address is configured for a test operation. The destination IP address must be the same as that of the listening service on the NQA server. |
5. Configure the destination port of voice probe packets. | destination port port-number | By default, no destination port number is configured. The destination port must be the same as that of the listening service on the NQA server. |
6. Configure the codec type. | codec-type { g711a | g711u | g729a } | Optional. By default, the codec type is G.711 A-law. |
7. Configure the advantage factor for calculating MOS and ICPIF values. | advantage-factor factor | Optional. By default, the advantage factor is 0. |
8. Specify the source IP address of probe packets. | source ip ip-address | Optional. By default, no source IP address is specified. The source IP address must be the IP address of a local interface. The local interface must be up. Otherwise, no probe packets can be sent out. |
9. Specify the source port number of probe packets. | source port port-number | Optional. By default, no source port number is specified. |
10. Configure the size of the data field in each probe packet. | data-size size | Optional. By default, the probe packet size depends on the codec type. The default packet size is 172 bytes for G.711A-law and G.711 µ-law codec type, and 32 bytes for G.729 A-law codec type. |
11. Configure the string to be filled in the data field of each probe packet. | data-fill string | Optional. By default, the string is the hexadecimal number 00010203040506070809. |
12. Configure the number of probe packets to be sent during each voice probe operation. | probe packet-number packet-number | Optional. 1000 by default. |
13. Configure the interval for sending probe packets during each voice probe operation. | probe packet-interval packet-interval | Optional. 20 milliseconds by default. |
14. Configure the interval the NQA client must wait for a response from the server before it regards the response times out. | probe packet-timeout packet-timeout | Optional. 5000 milliseconds by default. |
15. Configure optional parameters. | Optional. |