Cisco Systems uBR7200 Series manual Set Cable Flap List Power Adjustment Threshold

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.

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.

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 4-24 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.
	Cisco uBR7200 Series Universal Broadband Router Software Configuration Guide
4-42		78-5897-01