International Business Machines Corporation

Robert W Downes

Kenneth Harvey Potter, Jr

Wilson Earl Smith

Arthur Latimer Bond

Frederick K Yu

George Michel Abdelnour

Kenneth T Wilson

Ronald E Suciu

Controller triple modular redundancy is substantially achieved and reliability improved in a system having duplicate controllers that serve peripheral units. Both controllers detect suspected faults in itself and in the other controller. A peripheral unit that suspects a faulty active controller requests a switch of the active controller. A voting circuit processes votes from the controllers and the active controller switch signal from the peripheral units to select the active controller. The signaling paths between the controllers used to convey votes and active controller information are duplicated. The signals on these signaling paths convey information by using oscillating signals of different frequencies.

Method and apparatus for interface dual modular redundancy

A method for correcting error weights in a communication system in which at least one error condition can result from more than one cause. Stations on the system send error reports to an error monitor station which maintains a count of the number of stations reporting an error having multiple causes and periodically corrects the error weights assigned to each station as a function of the maximum number of errors reported by any station only when the number of stations reporting a multiple cause error exceeds a predetermined value.

Apparatus and method for isolating and predicting errors in a local area

Stations of a communications network maintain a set of counters which measure the frequency of occurrence of soft errors in said network. Periodically, each station generates and transmits an error report containing the error counts to a ring error monitor provided in one of the stations. The ring error monitor analyzes the report and calculates and stores weighted error counts for stations in an error domain. The stored error counts are integrated, over a selected time interval, and compared with a threshold value normal for a communications network, operating at acceptable error rate. The results of the comparison set error flags if the limits are exceeded indicating possible future station failures.

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Raleigh, NC, United States of America

Robert W Downes