A sequence number is an ordinal value attached to a Syslog message to identify its position in the sequence of generated log messages. It is optional, and Cisco IOS commonly omits it by default. section 7.2.1 section 7.2
Configure sequence numbers operationally with:
- service sequence-numbers — enables sequence numbers globally for future Syslog messages. section 7.2.1
- Previously generated messages are not changed after the command is entered. section 7.2.1
- A formatted Syslog message places the sequence number before the timestamp: seq:timestamp: %facility-severity-mnemonic: description. section 7.3
Numbered Syslog message
000065: Sep 19 01:01:01.133: %LINK-3-UPDOWN: Interface FastEthernet0/1, changed state to down. Here, 000065 identifies the message's order; the remaining fields provide time, source, severity, event mnemonic, and details. section 7.2
000065: Sep 19 01:01:01.133: %LINK-3-UPDOWN: Interface FastEthernet0/1, changed state to down
Inspect the complete Cisco IOS Syslog example to see the sequence number in its message-format position. section 7.2
