47-17
Cisco Catalyst Blade Switch 3130 and 3032 for Dell Software Configuration Guide
OL-12247-04
Chapter 47 Troubleshooting
Using Debug Commands
Using Debug Commands
These sections explains how you use
debug
commands to diagnose and resolve internetworking
problems:
•
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
Caution
Because debugging output is assigned high priority in the CPU process, it can render the system
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.
Note
For complete syntax and usage information for specific
debug
commands, see the command reference
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:
•
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.
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