Chapter 22: Channel Bonding
STANDARD Revision 1.0
C4® CMTS Release 8.3 User Guide
© 2016 ARRIS Enterprises LLC. All Rights Reserved.
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Recover Impaired US After REG/DBC: {disabled | indefiniteRecovery}
Ranging Timing Offset
Some modems do not calculate their timing offset for the non-primary upstream channels correctly which may cause
modems to become impaired. A CLI command provides an option to enter a specific ranging timing parameter that
specifies the offset, if needed. The default value for the parameter is zero which indicates that there is no offset.
The offset values are units in terms of 10.24 MHz clock cycles which can be negative or positive values.
A negative value indicates that the ranging offset is decreased which causes the modem to delay sending a RNG-REQ
(range request) transmission by the number of units - or 10.24 MHz clock cycles- specified.
Selecting a positive value will likewise cause the modem to send the RNG-REQ earlier by the number of specified units -
or 10.24 MHz clock cycles.
Note: When configured, the offset is across the entire CER.
Field experience has shown that some modems have a behavior of transmitting early on their non-primary upstream
channels during upstream channel acquisition during modem registration. This can cause the ranging request to be lost,
resulting in an impaired upstream channel. The recommended value of -48 can be used to compensate for this modem
behavior at registration, without negatively impacting other bonded modems that do not exhibit this behavior.
The command used to configure the ranging offset value is:
configure cable global ranging-timing-offset <int>
Where: <int> is -512 to 512 units based on 10.24 MHz clock cycles.
The
no
option will reset offset to the default value of zero.
To display the value offset value that is configured, enter:
show cable global-settings
Downstream Impairment Detection and Recovery
The modem will go into downstream partial service during the process of modem registration when one or more bonded
downstream channels are not acquired. If at a later point in time the modem acquires one or more of the impaired
downstream channels, the modem will send a CM-STATUS message to the C4/c CMTS with a report of
