Cisco Broadband Cable Command Reference Guide

Chapter 2 Cisco Cable Modem Termination System Commands
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cable upstream modulation-profile
Note If the Cisco CMTS router is running Cisco IOS Release 12.1(3a)EC1 or a later 12.1 EC
release, the Dynamic Upstream Modulation feature on the Cisco uBR-MC16S line card
operates the same as it does on the other line cards.
When Dynamic Upstream Modulation is enabled and spectrum groups are configured on the same
interface, the line cards respond to excessive noise by taking the first corrective action, as
determined by the cable upstream hop-priority command (either frequency hopping or changing
to the secondary modulation profile). If noise conditions worsen, the line card takes the second
corrective action that has been defined, and if that fails, the line card takes the last corrective action.
Note The Dynamic Upstream Modulation feature uses the DOCSIS-specified thresholds for 16-QAM and
QPSK operation to determine when to switch modulation profiles. Cisco therefore recommends that the
primary profile use 16 -QAM or mixed 16-QAM/QPSK modulation, and that the second profile use
QPSK modulation. However, this is not mandatory, and the two profiles could be the same (16-QAM or
QPSK), but the secondary profile should still be considered a more robust profile than the primary profile
in terms of coping with noise conditions.
Tip Modulation profiles must be first created using the cable modulation-profile command before they can
be assigned using the cable upstream modulation-profile command.
Examples The following example assigns the primary modulation profile 2 and the secondary modulation profile 1
to upstream port 0 on the cable interface card in slot 3. This automatically enables the Dynamic
Upstream Modulation feature for all CMs using that upstream.
Router(config)# interface cable 3/0
Router(config-if)# cable upstream 0 modulation-profile 2 1
Router(config-if)#
Related Commands Command Description
cable modulation-profile Creates a cable modulation profile.
cable upstream
Determines the order of the corrective actions to be taken when ingress
hop-priority
noise exceeds the allowable value for an upstream.
show cable
modulation-profile
Displays the cable modulation profiles that have been created.
Cisco Broadband Cable Command Reference Guide
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