What are examples of Cisco IOS Syslog level 0 (emergency) messages? I have never come across one, nor have I been able to google for one.
Cisco has a large listing of Syslog Messages and Severity level here: Syslog Messages
This list includes Syslog Messages for the following:
- IOS Software Release 15SY
- IOS Software Release 12.2SY
- IOS Software Release 12.2SX
- ASA Services Module
For the IOS Guides, you have to drill into the individual error messages to find the severity level. The ASA has a specific section, breaking down the severity Level.
Per Cisco documentation, the ASA IOS does not actually list any Severity 0 (Emergency) level messages. After a quick glance, I was not able to come up with any IOS Syslog messages with a Severity 0 (although, some may be found after some deep digging into the documentation).
Cisco does not call out any reason for lack of Severity 0 messages. However, Cisco does allows users to reassign the severity of Syslog messages. I suspect the lack of default Severity 0 messages is to give users a custom level to which they can assign. The thought process could be that if a user needs to reassign a Syslog Message Severity Level, it must be very important and it will likely be assigned the highest severity level.