Инструкции По Установке для 3com S7906E

 

1-16 

Configure the source IP 
address of a probe request in a 
test operation 

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, the test will 
fail. 

Configure common optional 
parameters 

 

Optional 

 

 

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: 

z 

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. 

z 

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 15. A higher value represents a higher quality of a VoIP 

network. 

The evaluation of voice quality depends on users’ tolerance to voice quality, and this factor should be 

taken into consideration. For users with higher tolerance to voice quality, you can 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.