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Cisco uBR7200 Series Universal Broadband Router Software Configuration Guide
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Chapter4 Troubleshooting the System
Performing Amplitude Averaging
Note The threshold default is 1 dB. The tolerable valuedefault is 2 dB. The power adjustment
is 30 percent.
Caution Default settings are adequate for system operation. Amplitude averaging is an automatic
procedure. In general, Cisco does not recommend you adjust values. Cisco does
recommend, however, that you clean up your cable plant should you encounter flapping
cable modems.
Note In some instances, you might adjust certain values:
If CMs cannot complete ranging because they have reached maximum power levels, you
might try to set the tolerablevalue CONTINUE field to a larger value than the default of
2 dB. Valueslarger than 10 dB on “C” versions of cable modem cards, or 5 dB on FPGA
versions, are not recommended.
Ifthe flap list shows CMs with a large number of power adjustments, but the CMs are not
detectedas “noisy,” you might try to decrease the percentage for “noisy.”If you think too
many CMs are unnecessarily detected as “noisy,” you might try to increase it.
Set Frequency Threshold to Affect Power Adjustment
To control power adjustment methods by setting the frequency threshold, use thecable upstream
freq-adj averaginginterface configuration command. To disable power adjustments, use the no form
of this command.
cable upstream nfreq-adj averaging % of frequency adjustment
no cable upstream freq-adj averaging
Table4-27 Cable Upstream Power Adjust Syntax Descriptions
Syntax Valid Values
nSpecifies the upstream port number.
threshold # Specifiesthe power adjustment threshold. The threshold range is from
0 through 10 dB. The default is 1 dB.
tolerable value Determinesif the status of the RNG-RSP should be set to CONTINUE
orSUCCESS. The range is from 2 through 15 dB. The default is 2 dB.
% of power adjustment Specifies the percentage of power adjustment packets required to
switch from the regularpower adjustment method to the noise power
adjustment method. Range is from 10 through 100 percent. The
default is 30 percent.