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Cisco Broadband Cable Command Reference Guide
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Chapter 2 Cisco CMTS Configuration Commands
cable upstream hop-priority
2.
If no clean frequency is available, the Cisco uBR-MC16S uses the Dynamic Upstream Modulation
feature to switch the upstream to the secondary modulation profile.
3.
If the noise levels still exceed the CNR threshold value for the secondary modulation profile, and if
the upstream has been configured for a range of channel widths, the Cisco uBR-MC16S narrows the
channel width of the upstream by half. If the noise levels are still excessive, the channel width is
again cut in half, and this process continues until a clean upstream is found or the bandwidth is
reduced to the minimum channel width that has been configured using the
cable upstream channel-
width
command.
Allowable DOCSIS channel widths are 3.2 MHz, 1.6 MHz, 800 KHz, 400 KHz, and 200 KHz. If the
channel width drops to 200 KHz, but the noise still exceeds the SNR threshold, the CMs go offline.
Note
The default specifies only a single channel width of 1.6 MHz. If this is not changed to
specify a range of allowable channel widths (using the
cable upstream channel-width
command), the Cisco uBR-MC16S does not attempt to change the channel width.
To use the Dynamic Upstream Modulation feature, you must first create two modulation profiles (using
the
cable modulation-profile
command) and assign them to the upstream (using the
cable upstream
modulation-profile
command).
Examples
The following example shows that when ingress noise on the upstream exceeds the threshold allowed for
the primary modulation profile, the Cisco uBR-MC16S line card should first switch to the secondary
modulation profile, then try frequency hopping, and if that fails to correct problem, to finally try
narrowing the channel width:
Router(config)#
interface cable 3/0
Router(config-if)#
cable upstream 0 hop-priority modulation frequency channel-width
Router(config-if)#
exit
Router(config)#
Related Commands
Command
Description
cable modulation-profile
Creates a cable modulation profile.
cable upstream channel-
width
Configures an upstream for a range of allowable channel widths.
cable upstream
modulation-profile
Configures an upstream for one modulation profile (static profile) or two
modulation profiles (Dynamic Upstream Modulation).
show cable hop
Displays the current hop period and threshold for an upstream, along with
other statistics.
show cable modulation-
profile
Displays the cable modulation profiles that have been created.
Содержание Broadband Cable
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Страница 1216: ...6 214 Cisco Broadband Cable Command Reference Guide OL 1581 07 Chapter 6 Cable CPE Commands debug usb ...
Страница 1266: ...A 50 Cisco Broadband Cable Command Reference Guide OL 1581 07 Appendix A Using the ROM Monitor unset ...