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Cisco uBR7200 Series Universal Broadband Router Software Configuration Guide
OL-2239-03
Chapter 3 Configuring Cable Modem Interface Features
Configuring the Downstream Cable Modem Interface
Verifying the Downstream Ports
To determine if the downstream carrier is active (up), enter the show controllers cable command for the
downstream port that you just configured. For National Television Standards Committee (NTSC) 6
MHz
operations, see the following example:
Router# show controllers cable5/0 downstream
Cable5/0 Downstream is up
Frequency=96000000, Channel Width 6 MHz, 64-QAM, Symbol Rate 5.056941 Msps
FEC ITU-T J.83 Annex B, R/S Interleave I=32, J=4
Setting the Integrated Upconverter
The Cisco uBR7200 series router supports an integrated upconverter that outputs a DOCSIS RF signal
on the DS0 RF downstream port. To enable the integrated upconverter, you must do the following:
• Set the downstream frequency—The integrated upconverter must be configured for the digital
carrier frequency, which is the center frequency of the downstream RF carrier (the channel) for the
downstream port. The cable downstream frequency command configures the downstream center
frequency for the integrated upconverter.
Note The cable downstream frequency command has no effect on external upconverters. If you are using an
external upconverter, this command is informational only and you must configure the external
upconverter separately, using its own command procedures.
• Enable the integrated upconverter—The integrated upconverter is disabled by default and must be
enabled with the no cable downstream rf-shutdown command.
• Enable the cable interface—The cable interface on the Cisco uBR7200 series router must be enabled
before the integrated upconverter will output an RF signal.
Step 3
Router(config)# interface cable5/0
Router(config-if)#
Enters cable interface configuration mode.
In this example, the interface is downstream port 0 on the
cable
interface card installed in slot 1 of the
Cisco
uBR7200 series CMTS.
Step 4
Router(config-if)# cable downstream if-output
Router(config-if)# no cable downstream if-output
Default. Activates downstream digital data from the
Cisco
uBR7200 series router.
Deactivates downstream digital data. This command mutes
the IF output of the cable
interface card and shuts down the
interfaces.
Step 5
Router(config-if)# no shutdown
Places the downstream port in the “admin up” state.
Step 6
Router(config-if)# end
Router#
%SYS-5-CONFIG_I: Configured from console by
console
Returns to privileged EXEC mode.
This message is normal and does not indicate an error.
Command Purpose
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