Cisco Headend System Release 2.7 사용자 가이드
Defining Non-Responding DHCTs
4031374 Rev B
93
DHCT Memory and Hardware Issues
The following list contains some examples of DHCT memory and hardware issues
that might cause a DHCT to become a non-responder:
that might cause a DHCT to become a non-responder:
Outdated DHCT operating system — Early versions of the operating system
used in DHCTs had memory issues that might cause a DHCT to malfunction.
used in DHCTs had memory issues that might cause a DHCT to malfunction.
Miscellaneous internal failures — Internal components of the DHCT may fail and
cause the DHCT to become a non-responder.
cause the DHCT to become a non-responder.
Return-Path Network Conditions
The following list contains some return-path network conditions that might cause a
DHCT to become a non-responder:
DHCT to become a non-responder:
Laser clipping — Lasers that assist in return path communications may be
calibrated incorrectly, resulting in a distortion of signal.
calibrated incorrectly, resulting in a distortion of signal.
Over-utilization of existing design — installation technicians may have installed
more signal splitters on the network than designed.
more signal splitters on the network than designed.
Signal interference — The quality of the return transmission may be poor due to
ingress or intermodulation.
ingress or intermodulation.
Note: Ingress refers to noise from an external source; intermodulation refers to noise
generated from within the network.
generated from within the network.
Hardware Failures on the DBDS Network
The following list contains some DBDS network components that could cause
DHCTs to become non-responders should the network components fail:
DHCTs to become non-responders should the network components fail:
QPSK Modulator/Demodulator
-
Buffers full-Available memory for the standard operation of a modulator is
limited. Abnormal activity through the modulator may exhaust the available
memory and cause the modulator to reboot.
limited. Abnormal activity through the modulator may exhaust the available
memory and cause the modulator to reboot.
-
DHCT chattering-Numerous DHCTs trying to simultaneously sign on to the
network may interfere with return path transmissions and cause modulators
to reboot.
network may interfere with return path transmissions and cause modulators
to reboot.
-
Excessive numbers of DHCTs assigned to modulator-Too many DHCTs
assigned to a single modulator may overwhelm the modulator.
assigned to a single modulator may overwhelm the modulator.
Router/switch
-
The router or switch is improperly configured.