AILAN: a local area network diagnostic expert system

The authors introduce an expert system, called AILAN, which is an intelligent diagnostic system for local area networks (LAN). This system is unique in that it entirely relies only on data acquired from the broadcast communication channel of the LAN. No status reporting is required from any component on the network. Header fields of data frames, handshaking methods, error control, flow control and other management procedures are analyzed. AILAN then deduces automatically which components on the network is faulty, if there is any. The system consists of three major subsystems for data capture, anomaly detection and analysis. It also contains a LAN protocol descriptive language based on the LISP language that helps to prevent explosion in the number of rules generated. The system is described in detail and its effectiveness is illustrated by applying the system to four real cases