The system records every error encountered on the system links. Most of these events are not extraordinary unless they occur very often. The events are logged as they occur, leaving a trail to help analyze abnormal behavior exhibited by the endpoints attached to the links or the links themselves.

When a link goes down, an alarm is raised immediately. For EAL, INL, BFDL, and PACL link types, a MINOR alarm is raised. For every other link type, a WRN alarm is raised. Other alarming conditions that do not cause the link to go down get a WRN alarm, regardless of the link type.