Specifying the Facility and Severity of Messages to Include in the Log
Each system log message belongs to a facility, which is a group of messages that are either generated by the same software process or concern a similar condition or activity (such as authentication attempts). Each message is also preassigned a severity level, which indicates how seriously the triggering event affects router functions.
When you configure logging for a facility and destination, you specify a severity level for each facility. Messages from the facility that are rated at that level or higher are logged to the destination:
[edit system syslog](console | file filename | host destination | user username) {facility severity;}
