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Chapter 47
Troubleshooting
Using Debug Commands
These sections explains how you use debug commands to diagnose and resolve internetworking
problems:
•
•
•
Because debugging output is assigned high priority in the CPU process, it can render the system
Caution
unusable. For this reason, use debug commands only to troubleshoot specific problems or during
troubleshooting sessions with Cisco technical support staff. It is best to use debug commands during
periods of lower network traffic and fewer users. Debugging during these periods decreases the
likelihood that increased debug command processing overhead will affect system use.
For complete syntax and usage information for specific debug commands, see the command reference
Note
for this release.
Enabling Debugging on a Specific Feature
In a switch stack, when you enable debugging, it is enabled only on the stack master. To enable
debugging on a stack member, you must start a session from the stack master by using the session
switch-number privileged EXEC command. Then, enter the debug command at the command-line
prompt of the stack member.
All debug commands are entered in privileged EXEC mode, and most debug commands take no
arguments. For example, beginning in privileged EXEC mode, enter this command to enable the
debugging for Switched Port Analyzer (SPAN):
Switch# debug span-session
The switch continues to generate output until you enter the no form of the command.
If you enable a debug command and no output appears, consider these possibilities:
•
•
To disable debugging of SPAN, enter this command in privileged EXEC mode:
Switch# no debug span-session
Alternately, in privileged EXEC mode, you can enter the undebug form of the command:
Switch# undebug span-session
To display the state of each debugging option, enter this command in privileged EXEC mode:
Switch# show debugging
OL-12247-04
Enabling Debugging on a Specific Feature, page 47-17
Enabling All-System Diagnostics, page 47-18
Redirecting Debug and Error Message Output, page 47-18
The switch might not be properly configured to generate the type of traffic you want to monitor. Use
the show running-config command to check its configuration.
Even if the switch is properly configured, it might not generate the type of traffic you want to
monitor during the particular period that debugging is enabled. Depending on the feature you are
debugging, you can use commands such as the TCP/IP ping command to generate network traffic.
Cisco Catalyst Blade Switch 3130 and 3032 for Dell Software Configuration Guide
Using Debug Commands
47-17
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