Cisco Broadband Cable Command Reference Guide

Chapter 5 Cable CPE Commands
debug cable-modem mac log
Syntax Description
Command Modes Privileged EXEC
Command History
OL-1581-05
debug cable-modem mac log
To display comprehensive debugging messages for the cable interface MAC layer, use the debug
cable-modem mac log command in privileged EXEC mode. To turn off debugging for the MAC layer,
use the no form of this command.
Cisco uBR904, uBR905, uBR924, uBR925 cable access routers, Cisco CVA122 Cable Voice Adapter
debug cable-modem mac log [verbose]
no debug cable-modem mac log [verbose]
verbose (Optional) Displays periodic MAC layer events, such as ranging.
Release Modification
11.3(4)NA This command was introduced for the Cisco uBR904 cable access router.
12.0(4)XI1 Support was added for the Cisco uBR924 cable access router.
12.1(3)XL Support was added for the Cisco uBR905 cable access router.
12.1(5)XU1 Support was added for the Cisco CVA122 Cable Voice Adapter.
12.2(2)XA Support was added for the Cisco uBR925 cable access router.
Usage Guidelines The debug cable-modem mac log command is one of the most useful debugging tools because
MAC-layer 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, use the show controllers cable-modem number mac log command. The
same information is displayed by both commands.
Tip The debug cable-modem mac log command displays details about the MAC-layer processes. In
particular, this command displays the details of the CM’s registration and initialization process.
If the router 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 CM scans for a downstream frequency. The debug cable-modem mac log command displays
the log from oldest entry to newest entry.
After initial ranging is successful (dhcp_state has been reached), further RNG-REQ/RNG-RSP
messages and watchdog timer entries are suppressed from output unless the verbose keyword is used.
Note that CMAC_LOG_WATCHDOG_TIMER entries while in the maintenance_state are normal when
using the verbose keyword.
Cisco Broadband Cable Command Reference Guide
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