Chapter 4 Troubleshooting the System
Troubleshooting Using Cable Flap Lists
Following is a sample response to the show cable flap command:
uBR7200#show cable flap
Mac Addr | CableIF | Ins | Hit | Miss | CRC | Flap | Time |
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0010.9500.461f C3/0 U1 | 56 | 18857 | 887 | 0 | 1 | 116 | Jun 1 | 14:09:12 | |
0010.9500.446e C3/0 U1 | 38 | 18686 | 2935 | 0 | 1 | 80 | Jun 2 | 19:03:57 | |
0010.9500.38ec C3/0 U2 | 63 | 18932 | 1040 | 0 | 8 | 138 | Jun 2 | 23:50:53 | |
0010.9500.4474 C3/0 U2 | 65 | 18913 | 1053 | 0 | 3 | 137 | Jun 2 | 09:30:09 | |
0010.9500.4672 C3/0 U2 | 56 | 18990 | 2327 | 0 | 6 | 124 | Jun 2 | 10:44:14 | |
0010.9500.38f0 C3/0 U2 | 50 | 18964 | 2083 | 0 | 5 | 111 | Jun 2 | 20:46:56 | |
0010.9500.e8cb C3/0 U2 | 0 | 6537 | 183 | 0 | 1 | 5 | Jun 2 | 22:35:48 | |
0010.9500.38f6 C3/0 U3 | 50 | 19016 | 2511 | 0 | 2 | 104 | Jun 2 | 07:46:31 | |
0010.9500.4671 C3/0 U4 | 43 | 18755 | 3212 | 1 | 1 | 89 | Jun 1 | 19:36:20 | |
0010.9500.38eb C4/0 U0 | 57 | 36133 | 1608 | 0 | 6 | 126 | Jun 2 | 20:04:58 | |
0010.9500.3ce2 C4/0 U0 | 44 | 35315 | 1907 | 0 | 4 | 99 | Jun 2 | 16:42:47 | |
0010.9500.e8d0 C4/0 U2 | 0 | 13213 | 246 | 0 | 1 | 5 | Jun 3 | 04:15:30 | |
0010.9500.4674 C4/0 U4 | 56 | 36037 | 2379 | 0 | 4 | 121 | Jun 3 | 00:34:12 | |
0010.9500.4677 C4/0 U4 | 40 | 35781 | 2381 | 0 | 4 | 91 | Jun 2 | 12:14:38 | |
0010.9500.4614 C5/0 U5 | 40 | 21810 | 2362 | 0 | 502 | 586 | Jun 2 | 21:43:02 | |
0010.9500.3be9 C6/0 U5 | 63 | 22862 | 969 | 0 | 0 | 128 | Jun 1 | 14:09:03 | |
0010.9500.4609 C6/0 U5 | 55 | 22723 | 2127 | 0 | 0 | 112 | Jun 1 | 14:08:02 | |
0010.9500.3cb8 C6/0 U5 | 49 | 22607 | 1378 | 0 | 0 | 102 | Jun 1 | 14:08:58 | |
0010.9500.460d C6/0 U5 | 46 | 22477 | 2967 | 0 | 2 | 96 | Jun 2 | 17:03:48 | |
0010.9500.3cba C6/0 U5 | 39 | 22343 | 3058 | 0 | 0 | 81 | Jun 1 | 14:13:16 | |
0010.9500.3cb4 C6/0 U5 | 38 | 22238 | 2936 | 0 | 0 | 79 | Jun 1 | 14:09:26 | |
0010.9500.4612 C6/0 U5 | 38 | 22306 | 2928 | 0 | 0 | 79 | Jun 1 | 14:09:29 | |
The command line with an arrow next to it reveals a cable modem that is continuously flapping. A high flap rate indicates that the cable modem is power adjusting frequently. This can indicate a problem with an amplifier. The number reveals the number of times the CMTS instructed the cable modem to adjust the transmit power more than 3 dB.
Cable modems are automatically added to the flap list when any of the following conditions are detected:
•When the cable modem
•When intermittent keepalive messages are detected between the CMTS and the cable modem.
•When the cable modem’s upstream transmit power is adjusted beyond the
Display the Flap List
The flap list can be queried either using the standard Simple Network Management (SNMP) API or the CLI. Using any third party SNMP Management Information Base (MIB) browser, you can query the ccsFlapTable in the
Using the show cable flap list command, the flap list statistics are accessed. A sample appears below. Each of the columns in the display are described in Table
MAC ID___ CableIF |
| Ins _Hit__ | Miss | CRC | Flap ___Time____ | |||||||
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0010.7b6b.60ad C3/0 U0 | 0 | 14386 | 1390 | 1 | 38 | 41 | Nov 24 | 21:34:24 | ||||
0010.7b6b.65a3 | C3/0 | U0 | 0 | 14503 | 1264 | 1 | 33 | 37 | Nov | 24 | 21:28:09 | |
0010.7b6b.6b9d | C3/0 | U0 | 0 | 14060 | 1726 | 3 | 40 | 43 | Nov | 24 | 21:18:36 | |
Cisco uBR7200 Series Universal Broadband Router Software Configuration Guide
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