A logging buffer is RAM-resident storage for Cisco IOS Syslog messages, providing a historical view of device events after real-time console or VTY output has passed. section 7.1.3
Core behavior and operational commands:
- Enable or resize it with logging buffered [bytes]; buffering is enabled by default. section 7.1.3 section 7.3
- Inspect stored messages and general Syslog settings with show logging. section 7.1.3 section 7.3
- When full, the buffer retains newer messages by adding and removing entries in first-in, first-out order. section 7.1.3
- Check available memory with show memory before increasing the buffer size. section 7.1.3
SW1# show logging
. . .
Console logging: level debugging, 5014 messages #1
logged, xml disabled, filtering disabled #1
Monitor logging: level debugging, 1080 messages #1
logged, xml disabled, filtering disabled #1
Buffer logging: level debugging, 4500 messages #1
logged, xml disabled, filtering disabled #1
. . .
Trap logging: level informational, 18 message lines logged
Logging Source-Interface: VRF Name:
Log Buffer (4096 bytes): #2
. . .
Sep 18 10:35:06.528: %SEC_LOGIN-5-LOGIN_SUCCESS: Login
Success [user: jeremy] [Source: 192.168.1.224]
[localport: 22] at 19:35:06 JST Mon Sep 18 2023
Sep 18 10:35:14.539: %SYS-5-CONFIG_I: Configured from #3
console by jeremy on vty0 (192.168.1.224) #3
#1 Console, monitor (VTY line), and buffer logging are enabled by default.
#2 The logging buffer is 4,096 bytes in size.
#3 The most recent messages are shown at the bottom of the output.
The show logging listing identifies buffer logging status, message counts, allocated size, and recent stored messages. section 7.1.3
