Cisco UBR924 - uBR 924 Router Troubleshooting Tips page 67

debug cable-modem mac
To troubleshoot the Cisco uBR924 MAC layer, use the debug cable-modem mac command in
privileged EXEC mode. To turn the debugging messages off, use the no form of this command.
Syntax Description
log
verbose
messages
Defaults
No default behavior or values.
Command Modes
Privileged EXEC
Command History
Release
11.3 NA
Usage Guidelines
Of all the available debug cable modem commands, the most useful is debug cable-modem mac
log.
MAC log messages are written to a circular log file even when debugging is not turned on. These
messages include timestamps, events, and information pertinent to these events. Enter the debug
cable-modem mac log command to view MAC log messages. If you want to view this information
without entering debug mode, enter the show controllers cable-modem number mac log command.
The same information is displayed by both commands.
If the Cisco uBR924 interface fails to come up or resets periodically, the MAC log will show what
happened. For example, if an address is not obtained from the DHCP server, an error is logged,
initialization starts over, and the Cisco uBR924 scans for a downstream frequency. The debug
cable-modem mac log command displays the log from the oldest to the newest entry.
After initial ranging is successful (dhcp_state has been reached), further
messages and watchdog timer entries are suppressed from output unless the verbose keyword is
used. Note that
using the verbose keyword.
[no] debug cable-modem mac {log [verbose] | messages}
Realtime MAC log display.
(Optional) Displays periodic MAC layer events, such as ranging.
MAC layer management messages.
CMAC_LOG_WATCHDOG_TIMER
Modification
This command was first introduced.
entries while in the maintenance_state are normal when
Troubleshooting Tips for the Cisco uBR924 Cable Access Router 67
debug cable-modem mac
RNG-REQ/RNG-RSP