Cisco Router Configuration, Second Edition

Basic Logging

Cisco IOS devices have the capability to log messages about system activity. These log messages can be useful in tracking system activity, errors, and notifications. Logging uses eight levels of notification messages, as summarized in Table 7-1.

Table 7-1. Cisco IOS Logging Messages

Level	Description
Level 0—Emergencies	The system has become unusable.
Level 1—Alerts	Immediate action is needed to restore system stability.
Level 2—Critical	Critical conditions have occurred that may require attention.
Level 3—Errors	Error conditions have occurred that may help track problems.
Level 4—Warnings	Warning conditions have occurred that are not severe.
Level 5—Notifications	Normal but significant conditions bear notification.
Level 6—Informational	These ...