Chapter 6 Troubleshooting The System; Downstream Signals; Power Adjustment - Cisco uBR10012 Software Configuration Manual

Troubleshooting the System
This chapter contains troubleshooting information for various functions of your Cisco uBR10000 series
Cable Modem Termination System (CMTS) and includes the following sections:
Section
"Understanding show Command
Responses" section on page 6-2
"Using a Headend CM to Verify
Downstream Signals" section on
page 6-12
"Performing Amplitude Averaging"
section on page 6-12
"Setting Downstream Test Signals"
section on page 6-15
"Pinging Unresponsive CMs" section
on page 6-16
"Using Cable Interface debug
Commands" section on page 6-17
For detailed information about troubleshooting your CMTS platform using cable flap lists, refer to
Note
the chapter
Feature Guide
For additional online troubleshooting resources, visit the Cisco Technical Assistance Center's
Note
Troubleshooting Assistant Web page at http://te.cisco.com/SRVS/CGI-BIN/WEBCGI.EXE?New,KB=Cable.
OL-1520-05
"Flap List Troubleshooting for the Cisco CMTS"
on Cisco.com.
Cisco uBR10012 Universal Broadband Router Software Configuration Guide
C H A P T E R
Purpose
Provides show command options for deriving system
information.
Uses a Cisco uBR924 cable access modem to verify the
downstream signal originating from a
Cisco uBR10012 router.
The system uses an averaging algorithm to determine the
optimum power level for a CM with low carrier-to-noise ratio
that is making excessive power adjustments—known as
flapping. This section shows how you can interpret these
power adjustments as indicating unstable return path
connections.
Provides configuration commands that allow you to create
downstream test signals.
Allows a cable system administrator to quickly diagnose the
health of a channel between the Cisco uBR10000 series
cable interface and the CM.
Provides instructions for troubleshooting cable interface line
cards.
in the Cisco Cable Modem Termination
6
6-1