System monitoring server at high supervision level in a large system, minor error incidents should be masked to avoid a confusing user interface. There is also the possibility of alarm storming due to a major error being reflected at several stages in the signal chain. In order to cope with these challenges the VBC uses two techniques: windowing functionality and alarm aggregation. The windowing functionality ensures that only persisting errors and errors occurring frequently will result in high level alarms. The total level of errors, summed over a specified time window, must exceed a threshold before a high level alarm is raised. Alarm aggregation merges similar alarms into one, thus making the user interface easier to interpret. Extensive use of links in the GUI ensures that it is easy to arrive at the right device views providing detailed information about a high level alarm.