Cisco IOS Cookbook, 2nd Edition

Setting the Log Size

Problem

You want to change the size of the router’s log.

Solution

You can use the optional size attribute with the logging buffered configuration command to change the size of your router’s internal log buffer:

Router#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#logging buffered 16000
Router(config)#end 
Router#

Be careful, though, because adjusting the size of the router’s logging buffer wipes out all of the current contents of the buffer.

Discussion

The typical default size of a router’s logging buffer is 4,096 bytes (although some high-end routers will default to a higher value). A buffer of this size can hold approximately 50 log messages before overwriting occurs. Fifty messages, although better than no logging, is relatively small, and most engineers will want increase their buffer size to store more messages. To check the size of your router’s logging buffer, use the show buffer command:

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 debugging, 1 messages logged
    Logging Exception size (4096 bytes)
    Trap logging: level informational, 657 message lines logged
          
Log Buffer (16000 bytes): 
Router>

As you can see, this router’s buffer size is currently set to 16,000 bytes (roughly 16 KB).

The router will theoretically accept a wide ...