Explanation/Reference:
Cisco routers, switches, PIX and ASA firewalls prioritize log messages into 8 levels (0-7), as shown below:
LevelLevel NameDescription
0 Emergencies System is unusable
1 Alerts Immediate action needed
2 Critical Critical conditions
3 Errors Error conditions
4 Warnings Warning conditions
5 Notifications Informational messages
6 Informational Normal but significant conditions
7 Debugging Debugging messages
When you enable logging for a specific level, all logs of that severity and greater (numerically less) will be logged. In this case we can see that logging level of 3 (as seen by the 3 in "LINK-3-UPDOWN") and level 5 (as seen by the 5 in "LINEPROTO-5-UPDOWN") are shown, which means that logging level 5 must have been configured. As shown by the table, logging level 5 is Notifications.
Explanation Added.