Motorola BSR 2000, Руководство по настройке и управлению

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Release 1.0 Configuring the CMTS
526360-001-00 Rev. B MGBI 6-173
Table 6-20 describes how to interpret flap list statistics:
Table 6-20 Flap List Statistic Interpretations
Field Description
Hit and Miss The HIT and MISS columns are keepalive polling statistics between the
BSR and the CM. The station maintenance process occurs for every CM
approximately every 10 seconds. When the BSR receives a response
from the CM, the event is counted as a Hit. If the BSR does not receive a
response from the CM, the event is counted as a Miss. A CM will fail to
respond either because of noise or if it is down. CMs which only log
Misses and zero Hits are assumed to be powered off.
Misses are not desirable since this is usually an indication of a return path
problem; however, having a small number of misses is normal. The flap
count is incremented if there are M consecutive misses where M is
configured in the cable flap miss-threshold parameter. The parameter
value ranges from 1-12 with a default of 6.
Ideally, the HIT count should be much greater than the Miss counts. If a
CM has a HIT count much less than its MISS count, then registration is
failing. Noisy links cause the MISS/HIT ratio to deviate from a nominal 1%
or less. High Miss counts can indicate:
• Intermittent upstream possibly due to noise
• Laser clipping
• Common-path distortion
• Ingress or interference
Too much or too little upstream attenuation
P-Adj The station maintenance poll in the BSR constantly adjusts the CM
transmit power, frequency, and timing. The Power Adjustments (P-Adj)
column indicates the number of times the CM’s power adjustment
exceeded the threshold value. The power adjustment threshold may be
set using the
<cable flap power threshold > parameter with a value range
of 0-10 dB and a default value of 2 dB. Tuning this threshold is
recommended to decrease irrelevant entries in the flap list. Power
Adjustment values of 2 dB and below will continuously increment the
P-Adj counter. The CM transmitter step size is 1.5 dB, whereas the cable
interface may command 0.25 dB step sizes. Power adjustment flap
strongly suggests upstream plant problems such as:
• Amplifier degradation
• Poor connections
• Thermal sensitivity
Attenuation problem