Cisco IOS Cookbook, 2nd Edition

Enabling Local Router Logging

Problem

You want your router to record log messages, instead of just displaying them on the console.

Solution

Use the logging buffered configuration command to enable the local storage of router log messages:

Router#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#logging buffered informational
Router(config)#end 
Router#

Discussion

This feature causes the router to store all log messages to a revolving buffer called the logging buffer. Many network administrators find it convenient and useful to keep detailed router logs on the router itself. The router discards its oldest messages to make room for new ones. This ensures that the logging buffer contains the most recent messages without depleting the router’s RAM. You can use the show logging command to view this buffer:

Router>show logging
Syslog logging: enabled (0 messages dropped, 0 messages rate-limited, 0 flushes, 0 overruns)
    Console logging: level debugging, 653 messages logged
    Monitor logging: level debugging, 65 messages logged
    Buffer logging: level informational, 1 messages logged
    Logging Exception size (4096 bytes)
    Trap logging: level informational, 657 message lines logged
          
Log Buffer (4096 bytes):
Mar 26 09:02:25: %SEC-6-IPACCESSLOGS: list 99 denied 172.16.2.2 5 packets
Mar 26 09:04:56: %CLEAR-5-COUNTERS: Clear counter on all interfaces on vty1 
Mar 26 09:05:13: %SYS-5-CONFIG_I: Configured from console by ijbrown on vty1 
Router>

Note that the default ...