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CHAPTER
8-1
Cisco uBR7200 Series Universal Broadband Router Software Configuration Guide
OL-2239-03
8
Troubleshooting the System
This chapter contains troubleshooting information for various functions of your CiscouBR7200 series
Cable Modem Termination System (CMTS) and includes the following sections:
Note For detailed information about troubleshooting your CMTS platform using cable flap lists, refer to the
chapter “Flap List Troubleshooting for the Cisco CMTS” in the Cisco Cable Modem Termination System
Feature Guide on Cisco.com.
Section Purpose
“Understanding show Command
Responses” section on page8-2
Provides show command options for deriving system
information.
“Using a Headend Cable Modem to
Verify Downstream Signals” section
on page8-6
Uses a Cisco uBR924 cable access modem to verify the
downstream signal originating from a CiscouBR7200series
router.
“Performing Amplitude Averaging”
section on page8-7
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.
“Setting Downstream Test Signals”
section on page8-9
Provides configuration commands that allow you to create
downstream test signals.
“Pinging Unresponsive Cable
Modems” section on page8-10
Allows a cable system administrator to quickly diagnose the
health of a channel between the CiscouBR7200series
cableinterface and the CM.
“Using Cable Interface debug
Commands” section on page8-11
Provides instructions for troubleshooting cable interface line
cards.