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Troubleshooting Tips for the Cisco uBR904 Cable Modem 1
Troubleshooting Tips for the
Cisco uBR904 Cable Modem
The following sections are provided:
•
Feature Summary on page 1
•
Platforms on page 3
•
Supported MIBs and RFCs on page 3
•
CMTS to Cable Modem Network Topology on page 4
•
Troubleshooting Steps on page 5
•
Command Reference on page 16
•
Debug Commands on page 49
•
What to do Next on page 61
Feature Summary
This document describes the set of Cisco IOS troubleshooting commands that may be used by
multiple service operators (MSOs) to verify communication between a Cisco uBR904 cable modem
and other peripheral devices installed in the HFC network such as the headend Cisco uBR7246
router, a DHCP server, and a TFTP server.
Note
For an explanation of error messages displayed by the uBR904, see Cisco Cable CPE Error
Messages, viewable online at
www.cisco.com/univercd/cc/td/doc/product/cable/cab_modm/ubcmerrs.pdf .
Benefits
The uBR904 troubleshooting system provides the following benefits:
•
A MAC-layer system log file exists which provides a snapshot of detailed reasons why an
interface might reset, along with all the negotiations that occurred between the uBR904 cable
modem and the CMTS (a Cisco uBR7246 positioned at the headend). Over 220 possible
description fields exist in this log, which is displayed using the show controllers cable-modem
0 mac log command from privileged EXEC mode.
•
Debug does not need to be turned on to troubleshoot a uBR904 cable modem.