Cisco Headend System Release 2.7 User Guide
Chapter 9 Monitor DHCTs with the DHCT Status Reporting Utility
94
4031374 Rev B
-
The router or switch lacks sufficient processing capability. The router or
switch can act as a choke-point in the communication path. In extreme cases,
the QPSK modulator may reboot.
switch can act as a choke-point in the communication path. In extreme cases,
the QPSK modulator may reboot.
DBDS Configuration and Management Issues
The following list contains some conditions that might exist in the configuration of
the DNCS that may cause a DHCT to become a non-responder:
the DNCS that may cause a DHCT to become a non-responder:
Improper demodulator attenuation management — To maintain a
communication link with the QPSK demodulator, DHCTs should transmit at a
level between (and including) 25 to 55 dBmV (decibels with respect to 1
millivolt). Over time, DHCT transmission levels may shift too high or too low.
The shifting levels may cause significant numbers of DHCTs assigned to a
demodulator to become non-responders.
communication link with the QPSK demodulator, DHCTs should transmit at a
level between (and including) 25 to 55 dBmV (decibels with respect to 1
millivolt). Over time, DHCT transmission levels may shift too high or too low.
The shifting levels may cause significant numbers of DHCTs assigned to a
demodulator to become non-responders.
Improper DHCT inventory management — The DNCS database may fall out of
synchronization with the database of the billing vendor. This loss of
synchronization may cause the DNCS to try to poll DHCTs that are not actually
in subscribers' homes.
synchronization with the database of the billing vendor. This loss of
synchronization may cause the DNCS to try to poll DHCTs that are not actually
in subscribers' homes.
Failure to run the updateOUI utility — DHCTs that attempt to sign on to the
network using an incorrect organizationally unique identifier (OUI) are
unsuccessful.
network using an incorrect organizationally unique identifier (OUI) are
unsuccessful.
What Activities Can Minimize the Non-Responding Condition?
This section summarizes some actions that system operators can take to reduce the
non-responding condition on their network.
non-responding condition on their network.
Review Network Configuration
Often, an examination of your basic network configuration can eliminate some
conditions that cause DHCTs to become non-responders. Consider these points as
you examine your network:
conditions that cause DHCTs to become non-responders. Consider these points as
you examine your network:
Review your existing network topology. Verify that you have separately
partitioned each hub. You do not want noise or interference on one hub to affect
another hub.
partitioned each hub. You do not want noise or interference on one hub to affect
another hub.
Review the concentration of DHCTs assigned to your system's QPSK
modulators. Verify that DHCTs are assigned as evenly as possible to your
system's modulators. Be certain that you never have more than 16,000 DHCTs
assigned to any one modulator.
modulators. Verify that DHCTs are assigned as evenly as possible to your
system's modulators. Be certain that you never have more than 16,000 DHCTs
assigned to any one modulator.
Verify the integrity of all network elements. Examine your routers and switches
for proper throughput. Examine your power supplies, amplifiers, nodes, and
taps, elements that are frequently overlooked during an examination of a
for proper throughput. Examine your power supplies, amplifiers, nodes, and
taps, elements that are frequently overlooked during an examination of a