4-42
Cisco uBR7200 Series Universal Broadband Router Software Configuration Guide
78-5897-01
Chapter4 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 poweradjustment of a cable modem meets or exceeds the threshold, the cable modem is placed in
the flaplist. The valid range is from 1 to 10 dBmV.
Note A power adjustment threshold of less than 2dBmV might cause excessive flap list event
recording. Cisco recommends setting this threshold value to 3dBmV 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 acknowledgea MAC layer keepalive message from a cable modem card. An 8%
missrate is normal for the Cisco cable modemcards. 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.
Table4-23 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.
Table4-24 Instructions to Set Cable Flap List Miss Threshold
Command Purpose
CMTS01(config)# cable flap-list miss-threshold misses Specifythe number of MAC-layer keepalivemisses
that will result in the cable modems being place in
the flap list.