The following example shows how to set the size of the logging exception flush output to 4098 bytes:
Router> enable
Router# configure terminal
Router(config)# logging exception 4098
Router(config)#end
To display the state of system logging and the contents of the standard system logging buffer use "show logging" command.
Router#sh logging
Syslog logging: enabled (11 messages dropped, 6 messages rate-limited,
0 flushes, 0 overruns, xml disabled, filtering disabled)
No Active Message Discriminator.
No Inactive Message Discriminator.
Console logging: level debugging, 1029 messages logged, xml disabled,
filtering disabled
Monitor logging: level debugging, 0 messages logged, xml disabled,
filtering disabled
Buffer logging: disabled, xml disabled,
filtering disabled
Logging Exception size (4098 bytes)
Count and timestamp logging messages: disabled
Persistent logging: disabled
No active filter modules.
ESM: 0 messages dropped
Trap logging: level informational, 1039 message lines logged
Debugging and Logging
Cisco IOS software allows for detailed debugging for all protocols and processes running in the system for troubleshooting purposes. More information on debugging can be obtained in the Cisco IOS Debug Command Reference
Enabling a higher level of messages shows all lower-level messages as well. The debugging level, or level 7, shows all messages. System messages may also be buffered and seen using the show logging command in privileged mode. A user may also send logging messages to a syslog server using the logging host command in configuration mode. A syslog server can be configured on a UNIX device or PC to accept these messages from a router and place them in a file. This allows for large files containing system messages to be maintained, because you are not restricted by the amount of memory on the router.
Only Cisco IOS experts should enable and disable debug commands, because they can have a severe performance impact and should be used with care. Improper use might leave the system inaccessible and in a frozen state in which no packet forwarding takes place.
System messages are shown on the console and can be enabled for any session into the router. Different levels of severity can be configured for different access methods into the router. The eight message severity levels are as follows:
-
Emergency (severity 0)—The system is unusable
-
Alert (severity 1)—Immediate action is needed
-
Critical (severity 2)—Critical condition
-
Error (severity 3)—Error condition
-
Warning (severity 4)—Warning condition
-
Notification (severity 5)—Normal but significant condition
-
Informational (severity 6)—Informational message
-
Debugging (severity 7)—Debugging message
IOS(config)# logging console ?
<0-7> Logging severity level
alerts Immediate action needed (severity=1)
critical Critical conditions (severity=2)
debugging Debugging messages (severity=7)
emergencies System is unusable (severity=0)
errors Error conditions (severity=3)
guaranteed Guarantee console messages
informational Informational messages (severity=6)
notifications Normal but significant conditions (severity=5)
warnings Warning conditions (severity=4)
Related Information
