Technical information

ADC Telecommunications, Inc.
488 C
HAPTER 18: CONFIGURING AND MONITORING CABLE MODEM TERMINATION SYSTEMS
Viewing MAC Interface Statistics
To display the statistics for the MAC Interface level, follow this procedure:
1. In the MAC window, click the Statistics tab.
2. Perform a Refresh to retrieve the current MAC statistics. Refer to
Table 18-3.
Hardware MAP
Timer
Sets the time interval between the CMTS transmission of
MAP messages for each upstream channel. By default,
the setting is for 2000 microseconds. Changing this value
causes performance implications.
Periodic Ranging
Interval (seconds)
Defines the period during which the CMTS will offer a
ranging opportunity to each cable modem. By default,
Periodic Ranging is sent every 15 seconds. Acceptable
values are 5 to 30 seconds.
Plant Propagation
Delay
Specifies the maximum round-trip propagation delay in
the cable plant. This value is used to adjust the map lead
time. It is recommended that a low value be used to
reduce cable modem access delay.
For a cable plant of 25 miles, the recommended value is
400.
For a cable plant of 100 miles, the recommended value is
1600.
CMTS PLL State Phase-locked loops (PLL) are circuits that hunt and
synchronize to an external signal.
For normal CMTS operations, the CMTS PLL State should
be set to normal and the PLL Value should be zero.
PLL Value Read-only. For normal operation of a DOCSIS or
EuroDOCSIS module, the PLL value must be zero. A PLL
value of non-zero normally indicates a malfunction of the
DOCSIS or EuroDOCSIS module.
If the PLL Value is non-zero, then set the CMTS PLL State
to pllSet. Perform a Refresh, and if the PLL Value
continues to display a non-zero value, then this is an
indication of a malfunction of the module. Selecting
pllSet causes the PLL to immediately start the sequence to
hunt and synchronize on an external signal.
NOTE: pllSet is a debug feature and should be used with
caution.
Parameter Description