Step 3—Display the Cisco uBR924’s MAC Log File
Troubleshooting Tips for the Cisco uBR924 Cable Access Router 11
Step 3—Display the Cisco uBR924’s MAC Log File
A MAC-layer circular log file is stored inside the Cisco uBR924. This file contains a history of the
log messages such as state event activities and timestamps. This is the most valuable information for
troubleshooting the cable interface.
The MAC log file is displayed by entering the show controllers cable-modem 0 mac log command
from privileged EXEC mode.
The most useful display fields in this log file are the reported state changes. These fields are preceded
by the message CMAC_LOG_STATE_CHANGE. These fields show how the Cisco uBR924 progresses
through the various processes involved in establishing communication and registration with the
CMTS. The maintenance_state is the normal operational state; the wait_for_link_up_state is
the normal state when the interface is shut down.
Note Because the MAC log file only holds a snapshot of 1023 entries at a time, you should try to
display the Cisco uBR924’s log file within 5 minutes after the reset or problem occurs.
The following is the normal progression of states as displayed by the MAC log:
wait_for_link_up_state
ds_channel_scanning_state
wait_ucd_state
wait_map_state
ranging_1_state
ranging_2_state
dhcp_state
establish_tod_state
security_association_state
configuration_file_state
registration_state
establish_privacy_state
maintenance_state
Note To translate this output into more meaningful information, see “Step 4—Interpret the MAC
Log File and Take Action” on page13.
Following is an example of what the MAC log file looks like when the Cisco uBR924 interface
successfully comes up and registers with the CMTS. The output you see is directly related to the
messages that are exchanged between the Cisco uBR924 and the headend CMTS.
uBR924# show controllers cable-modem 0 mac log
508144.340 CMAC_LOG_DRIVER_INIT_IDB_RESET 0x08098FEA
508144.342 CMAC_LOG_LINK_DOWN
508144.344 CMAC_LOG_LINK_UP
508144.348 CMAC_LOG_STATE_CHANGE ds_channel_scanning_state
508144.350 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 88/453000000/855000000/6000000
508144.354 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 89/93000000/105000000/6000000
508144.356 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 90/111250000/117250000/6000000
508144.360 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 91/231012500/327012500/6000000
508144.362 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 92/333015000/333015000/6000000
508144.366 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 93/339012500/399012500/6000000
508144.370 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 94/405000000/447000000/6000000
508144.372 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 95/123015000/129015000/6000000
508144.376 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 96/135012500/135012500/6000000
508144.380 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 97/141000000/171000000/6000000
508144.382 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 98/219000000/225000000/6000000
508144.386 CMAC_LOG_WILL_SEARCH_DS_FREQUENCY_BAND 99/177000000/213000000/6000000