Cisco Broadband Cable Command Reference Guide

cable downstream if-output
cable downstream if-output
Syntax Description
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Cisco Broadband Cable Command Reference Guide
Chapter 2 Cisco Cable Modem Termination System Commands
To activate a downstream port on a cable interface and to generate either a standard modulated signal or
a test signal, use the cable downstream if-output command in cable interface configuration mode. To
disable all signal output on the intermediate frequency (IF) carrier and to shut down the interface, use
the no form of this command.
cable downstream if-output [continuous-wave | prbs]
no cable downstream if-output
Defaults The downstream interface is enabled for normal data use (cable downstream if-output).
Command Modes Interface configuration (cable interface only)
Command History
continuous-wave Outputs an unmodulated carrier signal on the downstream, shutting down
normal data network operations.
prbs Outputs a Pseudo Random Bit Stream (PRBS) test signal on the downstream,
shutting down normal data network operations.
Release Modification
11.3 XA This command was introduced.
12.0(7)XR2, 12.0(7)T, This command was modified to support Annex A (EuroDOCSIS)
12.(0)SC,12.1(2)EC1 downstreams, and the continuous-wave and prbs options were added.
Usage Guidelines Typically, a downstream is configured to output a modulated signal, using the cable downstream
if-output command, allowing data transmissions to be sent over the HFC cable network. However, this
command can also be used to test the cable plant or to shut down the interface completely:
cable downstream if-output continuous-wave—Generates an unmodulated, continuous sine wave
on the downstream interface. You can use a spectrum analyzer to verify the frequency, amplitude,
and power of the wave. The test signal continues on the downstream until you resume normal
modulated operations using the cable downstream if-output command.
cable downstream if-output prbs—Generates a PRBS test signal on the downstream interface. You
can use a spectrum analyzer to verify the frequency, amplitude, and power of the wave. The test
signal continues on the downstream until you resume normal modulated operations using the cable
downstream if-output command.
no cable downstream if-output—Terminates all signal output and shuts down the downstream
interface. The interface remains shut down until you reactive the downstream using the cable
downstream if-output command.
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