Cisco Systems uBR7200 Series Anleitung zur Fehlerbehebung PDF herunterladen (Seite 42)

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Cisco uBR7200 Series Universal Broadband Router Software Configuration Guide

78-5897-01

Chapter 4 Troubleshooting the System

Troubleshooting Using Cable Flap Lists

Set Cable Flap List Power Adjustment Threshold

You can specify the power adjustment threshold that will cause a flap-list event to be recorded. When

the power adjustment of a cable modem meets or exceeds the threshold, the cable modem is placed in

the flap list. The valid range is from 1 to 10 dBmV.

Note A power adjustment threshold of less than 2 dBmV might cause excessive flap list event

recording. Cisco recommends setting this threshold value to 3 dBmV or higher.

To set the power adjustment threshold for flap-list events, use the following command in global

configuration mode.

Verify Cable Flap List Power Adjustment Threshold

To verify the cable flap list power adjustment threshold, enter the show cable flap list command:

CMTS01# show cable flap list

Mac Addr CableIF Ins Hit Miss CRC P-Adj Flap Time

0010.7b6b.5d1d C3/0 U0 0 688 169 0 0 3 Nov 5 12:28:50

0010.7b6b.5e15 C3/0 U0 1 707 185 0 0 5 Nov 5 12:29:52

0010.7b6b.5e27 C3/0 U0 1 707 198 0 0 5 Nov 5 12:29:55

0010.7b6b.5d29 C3/0 U0 1 709 205 0 0 5 Nov 5 12:29:52

0010.7b6b.5e2b C3/0 U0 1 710 204 0 0 7 Nov 5 12:30:16

Set Cable Flap List Miss Threshold

You can specify the miss threshold for recording a flap-list event. A miss is the number of times a

cable modem does not acknowledge a MAC layer keepalive message from a cable modem card. An 8%

miss rate is normal for the Cisco cable modem cards. When the number of misses exceeds the threshold,

the cable modem is placed in the flap list.

Note A high miss rate can indicate intermittent upstream problems, fiber laser clipping, or

common-path distortion.

To set the miss threshold for recording a flap-list event, use the following command in global

configuration mode.

Table 4-23 Instruction to Set Cable Flap List Power Adjustment Threshold

Command Purpose

CMTS01(config)# cable flap-list power-adjust threshold dbmv Specify the minimum power adjustment that will

constitute a flap-list event.

Table 4-24 Instructions to Set Cable Flap List Miss Threshold

Command Purpose

CMTS01(config)# cable flap-list miss-threshold misses Specify the number of MAC-layer keepalive misses

that will result in the cable modems being place in

the flap list.

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Cisco Systems uBR7200 Series Anleitung zur Fehlerbehebung Seite 42