Troubleshooting guide

Troubleshooting the CMTS
4-49
Tips for Administrating Flap Lists
Follow these suggestions for administrating flap lists:
• Write script(s) to periodically poll the flap list.
• Analize and identify CM trends from the flap list data.
• Query the billing and administrative database for CM MAC address-to-street
address translation and generate reports. These reports can then be given to the
Customer Service Department or the cable plant’s Operations and
Maintenance Department. Maintenance personnel use the reports to see
patterns of flapping CMs, street addresses, and flap statistics that indicate
which amplifier or feeder lines are faulty. The reports also help troubleshoot
problems in the downstream and/or upstream path, and determine if a problem
is related to ingress noise or equipment.
Flap The Flap counter indicates the number of times the CM has flapped.
This counter is incremented when one of the following events is
detected:
Unusual CM insertion or re-registration attempts. The Flap and the Ins
counters are incremented when the CM tries to re-establish the RF link
with the BSR within a period of time that is less than the
user-configurable insertion interval value.
Abnormal Miss/Hit ratio The Flap counter is incremented when N
consecutive Misses are detected after a Hit where N can be
user-configurable with a default value of 6.
Unusual power adjustment The Flap and P-adj counters are
incremented when the CM’s upstream power is adjusted beyond a
user-configurable power level.
Time Time is the timestamp indicating the last time the CM flapped. The
value is based on the clock configured on the local BSR. If no time is
configured, this value is based on the current uptime of the BSR. When
a CM meets one of the three flap list criteria, the Flap counter is
incremented and Time is set to the current time.
Table 4-3 Flap List Statistic Interpretations
Field Description