System information

Configuring the CMTS
6-95
Using Flap Lists
Flap lists are used to collect statistics for determining CM problems on the network.
The CM flap list keeps track of the CM MAC address, up and down transitions,
registration events, missed periodic ranging packets, upstream power adjustments on
the BSR.
The following sections describe how Flap lists are used:
• Setting Flap List Parameters
• Using Flap Lists to Troubleshoot CM Problems
• Tips for Administering Flap Lists
Setting Flap List Parameters
Flap list parameters are configured to define a criteria for the proper functioning of
your cable network.
When a CM makes an insertion request more frequently than the defined insertion
time (the time allowed for CMs to complete registration), the CM is placed in the flap
list for recording. When the CM power adjustment meets or exceeds its predefined
threshold, the CM is placed in the flap list. You can specify the power adjustment
threshold to a value that will cause a flap-list event to be recorded. A miss rate is the
number of times a CM does not acknowledge a MAC layer keepalive message from a
CMTS. You can specify the number of seconds to record and retain flapping activity
for the CMs connected to the CMTS. The number of CMs that can be recorded in the
flap list is 8192 CMs.
Use the following options to set flap list parameters:
1. Use the cable flap-list aging command in Global Configuration mode to specify
flap list aging, the number of minutes a CM is kept in the flap list, as shown
below.
MOT(config)#cable flap-list aging {<1-860400>}
where:
1-860400 is the flap list aging value, expressed in minutes. The default flap
list aging value is 1440.