Date Added: Apr 2011
Large scale integrated services such as VoIP running over IP networks are the future of telecommunications. The high availability requirements of such services require scalable techniques for rapid diagnosis and localization of user-visible failures. However, state-of-the-art network event correlation techniques often produce alarms that cannot easily be correlated to customer visible impacts because they work in a "Bottom-up" fashion starting from device-level events and working upwards. In this paper, the authors develop a contrasting "Top-down" approach to problem diagnosis that starts from user visible defects such as call drops and works downwards by identifying the network level elements that are the most suggestive of the defects.