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Cisco uBR7200 Series Universal Broadband Router Software Configuration Guide
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Chapter4 Troubleshooting the System
Managing Cable Modems on the HFC Network
•Using time scheduled spectrum management, the upstream channel frequency reassignment
process is initiated at a configured time of day or week.
With combined blind and time scheduled strategies, blind hop tables are given time-variant
configurability.The frequency or subband list can change with time. Blind frequency hop is performed
within the spectrum specified to be currently available. An example follows:
uBR(config)# cable spectrum-group 2 time Mon 09:00:00 frequency 10000000
uBR(config)# cable spectrum-group 2 time Tue 09:05:00 delete frequency 10000000
uBR(config)# cable spectrum-group 2 time Tue 09:00:00 frequency 5000000
uBR(config)# cable spectrum-group 4 time Fri 09:00:00 band 15000000 25000000
uBR(config)# cable spectrum-group 4 time Sat 09:00:00 delete band 15000000 25000000
Guided Frequency Hop
Using guided frequency hop, the upstream channel frequency is reassigned if a threshold number or
percentage of cable modems suddenly go offline. You can adjust the thresholds and assign explicit
frequencies or frequency subbands and associated input power levels in the unified spectrum group
table. The Cisco uBR7200 series locates the definedchannel or a suitable channel and moves all cable
modems on the upstream port.
Theexample below shows the Cisco uBR7200 series’ ability to force the CTMS to change the upstream
to another frequency before the CMTS sends a message to increase output power levels. You can
configure the frequency hop table so that the next entry has the same frequency, but a different power
level:
uBR(config)# cable spectrum-group 2 frequency 20000000
uBR(config)# cable spectrum-group 2 frequency 20000000 2
uBR(config)# cable spectrum-group 2 frequency 20000000 -2
uBR(config)# cable spectrum-group 2 frequency 22000000
uBR(config)# cable spectrum-group 2 frequency 22000000 2
uBR(config)# cable spectrum-group 2 frequency 22000000 3
Theorder of the configuration commands defines the order which frequency or power level is changed.
There is alwaysa single allocation set per-spectrum group, listing the currently available bands. In the
case of a shared spectrum group, there is also a single free set and “in-use” set since there is a single
RF domain. Otherwise, there are free and in-use sets for each upstream port since each upstream port
has its own RF domain.