Syslog

Destinations for syslog messages
 * The logging buffer (RAM inside the router or switch)
 * The console line
 * The terminal lines
 * A syslog server

System Message Format
In a typical syslog message (default) you will have the following: *Dec 18 17:10:15.079: %LINEPROTO - 5 - UPDOWN:  Line protocol on Interface FastEthernet0/0, changed state to down

Timestamp The facility on the router that generated the message Severity level Mnemonic for the message Description of the message

Modifying the System Message Format
service sequence-numbers - enables sequence numbers on logging messages service timestamps - enables timestamps on the logging messages For timestamps there are several options for this in regards to the time shown: service timestamps log uptime - shows system uptime service timestamps log datetime service timestamps log datetime localtime service timestamps log datetime localtime show-timezone msec year - all time features The above command shows the following output: 000024: *Mar 1 2002 00:05:30.579 UTC: %SYS-5-CONFIG_I: Configured from console by console

System Message Severity Levels
Debugging Informational Notification Warning Error Critical Alert Emergency

The logging buffer (RAM inside the router or switch)
Send system logs to the internal system buffer. logging buffered

The console line
By default, all messages are sent to the console. logging console

A syslog server
To send messages to a syslog server, just identify the server IP and specify the trap level. logging 192.168.1.1 logging trap 4

Reading the Logger Output
R1#show logging Syslog logging: enabled (12 messages dropped, 1 messages rate-limited,                0 flushes, 0 overruns, xml disabled, filtering disabled) Console logging: level debugging, 14 messages logged, xml disabled, filtering disabled Monitor logging: level debugging, 0 messages logged, xml disabled, filtering disabled Buffer logging: level debugging, 1 messages logged, xml disabled, filtering disabled Logging Exception size (4096 bytes) Count and timestamp logging messages: disabled No active filter modules. Trap logging: level informational, 17 message lines logged Log Buffer (4096 bytes):