Cisco Systems uBR7200 Series Anleitung zur Fehlerbehebung PDF herunterladen (Seite 46)

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Cisco uBR7200 Series Universal Broadband Router Software Configuration Guide

78-5897-01

Chapter 4 Troubleshooting the System

Performing Amplitude Averaging

Note The threshold default is 1 dB. The tolerable value default 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 tolerable value CONTINUE field to a larger value than the default of

2 dB. Values larger than 10 dB on “C” versions of cable modem cards, or 5 dB on FPGA

versions, are not recommended.

If the flap list shows CMs with a large number of power adjustments, but the CMs are not

detected as “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 the cable upstream

freq-adj averaging interface configuration command. To disable power adjustments, use the no form

of this command.

cable upstream n freq-adj averaging % of frequency adjustment

no cable upstream freq-adj averaging

Table 4-27 Cable Upstream Power Adjust Syntax Descriptions

Syntax Valid Values

n Specifies the upstream port number.

threshold # Specifies the power adjustment threshold. The threshold range is from

0 through 10 dB. The default is 1 dB.

tolerable value Determines if the status of the RNG-RSP should be set to CONTINUE

or SUCCESS. 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 regular power adjustment method to the noise power

adjustment method. Range is from 10 through 100 percent. The

default is 30 percent.

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Cisco Systems uBR7200 Series Anleitung zur Fehlerbehebung Seite 46