Debug commands

All debug commands are entered in privileged EXEC mode, and most debug commands take no arguments. For example, to enable the debug atm packet command, 

Switch# debug atm packet

ATM packets debugging is on
Displaying all ATM packets
 

To display the state of each debugging 

Switch# show debugging

Generic ATM:
  ATM packets debugging is on
Switch#
 

To turn off the debug atm packet command in privileged EXEC mode enter the no 

Switch# no debug atm packet

ATM packets debugging is off
Switch#
 

Alternately, in privileged EXEC mode, you can enter the undebug form of the command:

Switch# undebug atm packet

ATM packets debugging is off
Switch#

To list and see a brief description of all the debugging command 

Switch# debug ?

  aaa                 AAA Authentication, Authorization and Accounting
  all                 Enable all debugging
  arp                 IP ARP and HP Probe transactions
  async               Async interface informati