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Cisco IE 3000 Switch Software Configuration Guide
OL-13018-03
Chapter 39 Troubleshooting
Using Debug Commands
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
Enabling All-System Diagnostics
Beginning in privileged EXEC mode, enter this command to enable all-system diagnostics:
Switch#
debug all
Caution
Because debugging output takes priority over other network traffic, and because the
debug all
privileged
EXEC command generates more output than any other
debug
command, it can severely diminish switch
performance or even render it unusable. In virtually all cases, it is best to use more specific
debug
commands.
The
no debug all
privileged EXEC command disables all diagnostic output. Using the
no debug all
command is a convenient way to ensure that you have not accidentally left any
debug
commands
enabled.
Redirecting Debug and Error Message Output
By default, the network server sends the output from
debug
commands and system error messages to the
console. If you use this default, you can use a virtual terminal connection to monitor debug output
instead of connecting to the console port.
Possible destinations include the console, virtual terminals, internal buffer, and UNIX hosts running a
syslog server. The syslog format is compatible with 4.3 Berkeley Standard Distribution (BSD) UNIX
and its derivatives.
Note
Be aware that the debugging destination you use affects system overhead. Logging messages to the
console produces very high overhead, whereas logging messages to a virtual terminal produces less
overhead. Logging messages to a syslog server produces even less, and logging to an internal buffer
produces the least overhead of any method.
For more information about system message logging, see
Chapter 32, “Configuring System Message
Logging.”
