Increase or change Cisco router log size

Contributed by qmchenry  
Tagged: Cisco router  

Messages logged by a router can make troubleshooting problems substantially easier. However, the default size of most Cisco routers is 4096 bytes which typically accomodates fewer than 60 messages. While this may help in many situations, adding some additional space can save the day when a router generates frequent error messages as when an interface state cycles up and down. This recipe describes the simple configuration to increase the size of the router log.

To increase the router log size to 24000 bytes, use the following commands (from enable mode):

conf t
logging buffered 24000


To check the current log size, use this command:

show logging
...
Log Buffer (24000 bytes)


It should be noted that memory you dedicate to the log is memory the router cannot use for routing. Larger routers with lots of memory can typically make due with less available memory. Smaller routers with less memory to spare can experience problems if the log size is too big.