Troubleshooting guide

7-27
Cisco Broadband Local Integrated Services Solution Troubleshooting Guide
OL-5169-01
Chapter 7 Troubleshooting the CMTS
Troubleshooting the Cisco uBR7246VXR
Sample:
MAC ID___ CableIF Ins _Hit__ Miss CRC P-Adj Flap ___Time____
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
Table 7-2 Flap List Statistics Description
Statistic Description
MAC ID This is the MAC-layer address of a cable modem. The first six digits indicate the
vendor ID of the cable modem manufacturer, followed by six digits indicating a
unique host address. Each cable modem's MAC address is unique.
Cable IF This is the physical upstream interface on the Cisco uBR7200. It denotes the
cable modem card slot number, the downstream port number on the RF line card
and the upstream port number on the same cable modem card. The flap list data
can be sorted based on the upstream port number which is useful when isolating
reverse path problems unique to certain combining groups.
Insertions Link insertion is the initial maintenance procedure of a cable modem establishing
link with the Cisco uBR7246VXR. The Ins column is the flapping modem's
insertion count and indicates the number of times the RF link was abnormally
re-established. An abnormality is detected when the time between link
re-establishment attempts is less than the user-configured parameter.
Normal modem activity follows the sequence below:
• The initial link insertion is followed by a keepalive loop between the Cisco
uBR7246VXR and cable modem and is called station maintenance.
• Power-on
• Initial maintenance
• Station maintenance
• Power-off
When the link is broken, initial maintenance is repeated to re-establish the link.
• Initial maintenance @ Time T1
• Station maintenance
• Init maintenance @ Time T2
The Ins and Flap counters in the flap list are increased whenever T2 - T1 < N
where N is the insertion-time parameter configured in <cable flap-list
insertion-time>. Default value for this parameter is TBD seconds.
A high Ins number indicates:
• Intermittent downstream sync loss
• DHCP or modem registration problems