Cisco Cisco IOS Software Release 12.1(7)CX
Configuration Example
20
Advanced Spectrum Management Features for the Cisco uBR-MC16S Spectrum Management Card
Cisco IOS Release 12.1(7)CX1
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The DCMTA software should be used for live troubleshooting of specific problems in the return
path. Do not use DCMTA for ongoing monitoring because it requests a large volume of data for each
SNMP request, and constant use could affect network bandwidth and the overall performance of the
Cisco uBR7200 series CMTS. For best results, the DCMTA software should be launched when
needed and then exited after the return path problem has been resolved.
path. Do not use DCMTA for ongoing monitoring because it requests a large volume of data for each
SNMP request, and constant use could affect network bandwidth and the overall performance of the
Cisco uBR7200 series CMTS. For best results, the DCMTA software should be launched when
needed and then exited after the return path problem has been resolved.
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Because the DCMTA software uses SNMP polling to obtain the spectrum management data, its
graphical displays show a digital representation that appears more jagged than the analog swept
spectrum displays that are generated by hardware spectrum analyzers.
graphical displays show a digital representation that appears more jagged than the analog swept
spectrum displays that are generated by hardware spectrum analyzers.
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When monitoring individual cable modems, the DCMTA graphical displays could show the cable
modem missing for several seconds, even though the cable modem is still connected and online. This
can happen for two reasons:
modem missing for several seconds, even though the cable modem is still connected and online. This
can happen for two reasons:
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The DOCSIS specification allows a CMTS to periodically miss a ranging burst from a cable
modem without affecting the cable modem’s connectivity. If this occurs while the DCMTA
software is monitoring a particular cable modem, the graphical display could show that cable
modem missing for several seconds.
modem without affecting the cable modem’s connectivity. If this occurs while the DCMTA
software is monitoring a particular cable modem, the graphical display could show that cable
modem missing for several seconds.
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The DMCTA software uses SNMP requests to obtain its spectrum management data. Because
SNMP is based on the connectionless UDP protocol, it is possible that SNMP packets can be
dropped or lost by the routers and other network devices between the Cisco uBR7200 series
CMTS and DCMTA PC. If this happens, the graphical display could show a drop in the spectrum
that was described by the data that was contained in the lost packets.
SNMP is based on the connectionless UDP protocol, it is possible that SNMP packets can be
dropped or lost by the routers and other network devices between the Cisco uBR7200 series
CMTS and DCMTA PC. If this happens, the graphical display could show a drop in the spectrum
that was described by the data that was contained in the lost packets.
In both of these cases, the missing spectrum data should reappear quickly, within several seconds.
If it does, and if no further problems occur with that particular cable modem or spectrum, then the
problem is likely due to the transient network problems described above.
If it does, and if no further problems occur with that particular cable modem or spectrum, then the
problem is likely due to the transient network problems described above.
Configuration Example
This section provides a typical configuration example for a Cisco uBR7200 series router using the
Cisco uBR-MC16S cable interface line card. This configuration does the following:
Cisco uBR-MC16S cable interface line card. This configuration does the following:
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Creates three spectrum groups with different frequency bands, hop periods, and hop thresholds.
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Creates two upstream modulation profiles, one for QPSK operation and one for 16-QAM operation
by specifying the parameters for each burst type.
by specifying the parameters for each burst type.
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Creates two upstream modulation profiles, one for QPSK operation and one for mixed
QPSK/16-QAM operation, using the default profile options (qpsk and mix).
QPSK/16-QAM operation, using the default profile options (qpsk and mix).
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Configures one upstream (port 5) on cable interface 3/0 to use spectrum group 3.
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Configures the upstreams with the primary modulation profile set to mixed QPSK/16-QAM
operation and the secondary modulation profile set for QPSK operation.
operation and the secondary modulation profile set for QPSK operation.
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Configures the upstream so that when its noise threshold is reached, it first attempts to change the
frequency, then the channel-width, and finally to switch the modulation profile (using the Dynamic
Upstream Modulation feature).
frequency, then the channel-width, and finally to switch the modulation profile (using the Dynamic
Upstream Modulation feature).
!
version 12.1
no service pad
no service password-encryption
service udp-small-servers
service tcp-small-servers
!
hostname ubr7200
!