Specifications

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Cisco Cable Modem Termination System Feature Guide
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Chapter 3 Spectrum Management for the Cisco Cable Modem Termination System
Restrictions and Limitations
Note This default is being tracked by caveat CSCdx35070.
• When using Cisco IOS Release 12.2(8)BC2, in rare situations, using CLI commands to configure
the Cisco uBR-LCP2-MC16 card could result in the error message "Resources are busy with other
msg requests. Try later." The workaround is to repeat the same configuration command again until
the error disappears.
Cisco uBR-MC16S Line Card
• The initial Intelligent spectrum management enhancements to the Cisco uBR-MC16S line card were
introduced in the Cisco IOS Release 12.1 EC train. The Advanced spectrum management features,
including CNR-based proactive frequency hopping, require Cisco IOS Release 12.2(8)BC2 and
later 12.2 BC releases.
• The Cisco uBR-MC16S line card is supported on the Cisco uBR7200 series routers and on the
Cisco uBR10012 router. It is not supported on Cisco uBR7100 series router.
• The Cisco uBR-MC16S line card is not supported in any release of Cisco IOS Release 12.0SC.
• Upstream channels must meet the CNR and carrier-to-ingress power ratio values given in the
DOCSIS specifications. The minimum value for both parameters is 25 dB in the 5–42 MHz
frequency range.
• The Advanced Spectrum Management features do not support shared spectrum groups, requiring
that each upstream port on the Cisco uBR-MC16S line card must have its own RF domain (a unique
set of non-overlapping frequencies).
• HCCP 1+1 redundancy is not supported on any cable interface line card that has defined spectrum
groups, which typically is the normal configuration for the Cisco uBR-MC16S line card.
Fixed-Frequency Spectrum Groups with the Cisco uBR-MC16S Card
When using the Cisco uBR-MC16S cable interface line card, do not configure fixed-frequency spectrum
groups by specifying a single frequency using the cable spectrum-group frequency command (for
example, cable spectrum-group 3 frequency 76000000). If single-frequency spectrum groups are
desired, configure a band with a starting and ending range, which, along with the desired channel width,
specifies the desired center frequency. In this situation, you must also configure a static channel width
so that the Dynamic Upstream Modulation feature does not attempt to hop to a different frequency using
a smaller channel width.
For example, to specify a center frequency of 7.6 MHz with a 3.2 MHz channel width, specify a starting
frequency of 6.0 MHz (7.6 MHz - 1.6 MHz) and an ending frequency of 9.2 MHz (7.6 MHz + 1.6 MHz):
CMTS(config)# cable spectrum-group 15 band 6000000 9200000
CMTS(config)# int c6/0
CMTS(config-if)# cable upstream 0 channel-width 3200000 3200000
CMTS(config-if)# cable upstream 0 spectrum-group 15
Note Cisco IOS Release 12.2(8)BC2 does not support fixed-frequency spectrum groups.
DOCSIS Cable Modem Test Analyzer
Cisco IOS Release 12.2(8)BC2 and later 12.2 BC releases and the Cisco uBR-MC16S cable interface
line card support the DOCSIS Cable Modem Test Analyzer (DCMTA) software from Acterna Corp. This
spectrum management tool is designed for troubleshooting ingress and other problems on the return path
in real time, not for ongoing monitoring of the upstream spectrum.