Abstract: Disclosed is a system that monitors a local area network by receiving all messages transmitted over the local area network, and analyzing selected sequences of messages to determine if certain, architecturally defined, processes are properly completed. If a network station starts one of these processes, and the process does not complete normally, the system analyzes the messages involved in the process to determine the network stations that participated in the process, and the phase or phases of the process that were completed. This allows the system to provide information to a user of the system that identifies a possible cause for the process not completing, and a possible network station or stations likely to be at fault.

Abstract: A system that monitors a local area network by receiving all messages transmitted over the local area network, and analyzing selected sequences of messages to determine if certain, architecturally defined, processes are properly completed. If a network station starts one of these processes, and the process does not complete normally, the system analyzes the messages involved in the process to determine the network stations that participated in the process, and the phase or phases of the process that were completed. This allows the system to provide information to a user of the system that identifies a possible cause for the process not completing, and a possible network station or stations likely to be at fault.

Abstract: A method and apparatus which measures the electrical cable length of a ring in an active Token-Ring local area network. The system determines the data transmission speed of the ring, the type of cable being used to connect the stations of the ring, the manufacturer of the circuitry used in the active monitor station, and the number of standby monitors actively connected to the ring. The system determines the time between two successive tokens having no intervening non-token frames, and then subtracts the amount of delay through the active monitor station and the amount of delay through each of the standby monitor stations. It then multiplies this result by the speed of light and by a velocity constant determined by the type of cable being used, to produce the total cable length between all active stations on the ring.