Troubleshooting guide

11-2
Cisco Broadband Local Integrated Services Solution Troubleshooting Guide
OL-5169-01
Chapter 11 Element Management and MIBs
Cisco uBR7246vxr MIBs
There are 3 flap detectors defined. The flap count (ccsFlapTotal) is increased when any one of the flap
detectors is triggered.
(1) Registration Flap: A CM may fail the registration process due to not being able to get an IP address.
When that happens the CMTS will receive the Initial Maintenance packet from the CM sooner than
expected and the CM is considered a flapping modem. In addition to the flap count ccsFlapInsertionFails
will be increased; thus these two counters may tend to track each other for unauthorized modems.
Another causes of registration flap may be downstream loss of sync or upstream ranging failure.
(2) Station Maintenance Flap: When the CMTS receives a Miss followed by a Hit then the modem will
be added into the Flap List and the flap count will be increased. If ratio of Miss/Hit is high, then an
upstream impairment is indicated.
(3) Power Adjustment Flap: When the CM upstream transmit power is adjusted and the adjustment is
greater than the threshold (ccsPowerAdjustThreshold), the modem is added into the Flap List. In
addition to the flap count ccsFlapPowerAdjustCnt will be increased. Excessive power adjustment is an
indication of poor or failing plant components. It may also indicate the exposure of plant components to
the forces of wind, moisture, or temperature.
Table 11-1 CISCO-CABLE-SPECTRUM-MIB.my Objects
Object Description
ccsFlapListMaxSize The maximum number of modems that a flap list can support.
This number controls the size of the flap list. For every MAC
domain or downstream, the maximum number of MTAs that can
be supported is 8191. The user may want to increase or decrease
the Flap List size according to the number of downstreams and
the number of modem line cards in the CMTS.
When the number of modems exceeds the max flap list size, the
additional modems are ignored. The flap detector is an
information filter to avoid inundating a management agent with
data which is less meaningful as a function of size.
ccsFlapListCurrentSize The current number of modems in the flap list. Its value will be
less than or equal to ccsFlapListMaxSize.
ccsFlapAging The flap entry aging threshold. Periodically, the aging process
scans through the flap list and removes the MTAs that have not
flapped for that many minutes.
ccsFlapInsertionTime The insertion-time is an empirically derived, worst-case
number of seconds which the requires to complete registration.
The time taken by MTAs to complete their registration is
measured by the cable operators and this information helps to
determine the insertion time. If the MTA has not completed the
registration stage within this insertion-time setting, the MTA
will be inserted into the flap-list.
ccsFlapTable This table keeps the records of modem state changes. It can be
used to identify the problematic MTAs. An entry can be deleted
from the table but can not be added to the table.
ccsFlapEntry List of attributes for an entry in the ccsFlapTable. An entry in
this table exists for each MTA that triggered one of our flap
detectors.
ccsFlapMacAddr MAC address of the MTA's Cable interface. Identifies a flap-list
entry for a flapping MTA.