Fault-tolerant processing system architecture

A fault tolerance redundancy system for communication comprising:

• a pair of redundant service units each including a copy of a database;
• a pair of communication media both connected to each service unit;
• a plurality of served units, each connected to both communication media and each including a copy of the database;
• a first of the pair of redundant service units responsive to receipt of information from an information source by storing the received information in its copy of the database and communicating the received information individually to a second of the pair of redundant service units and to each served unit, the first of the pair of redundant service units alternately using a different one of the communication media to communicate the received information to successive ones of the second of the pair of redundant service units and the served units;
• the second of the pair of redundant service units responsive to receipt of the information from the first of the pair of redundant service units by storing the received information in its copy of the database and sending an acknowledgment of the receipt to the first of the pair of redundant service units, and communicating the received information individually to each served unit, the second of the pair of redundant service units alternately using a different one of the communication media to communicate the received information to successive ones of the served units;
• each served unit responsive to receipt of the information from one of the pair of redundant service units by storing the information received from the one of the pair of redundant service units in its copy of the database and sending an acknowledgment of the receipt across one of the communication media to the one of the pair of redundant service units, and further responsive to receipt of the information from another of the pair of redundant service units for discarding the information received form the other of the pair of redundant service units and sending an acknowledgment of the receipt across one of the media to the other of the pair of redundant service units;
• and
• each service unit further responsive to a failure to receive a timely acknowledgment, of receipt of the information that was communicated by said each service unit, from every served unit and service unit of the pair of redundant service units to which the information was communicated by said each service unit, within a predetermined period of time by subsequently communicating the information again to any served unit and service unit of the pair of redundant service units to which the information was communicated by said each service unit and from which the acknowledgment was not timely received.

A method of operating a redundancy apparatus that comprises a pair of redundant service units, a pair of communication media both connected to each service unit, and a plurality of served units, each connected to both communication media, comprising the steps of:

• in response to receipt by the redundancy apparatus of information for the served units, each service unit of the pair of redundant service units communicating the information individually to the served units, each service unit of the pair of redundant service units alternately using a different one of the communication media to communicate the information to successive ones of the served units;
• in response to receipt at any served unit of the information from one of the service units of the pair of redundant service units, the served unit using the information received from the one of the service units of the pair of redundant service units;
• and
• in response to receipt at the served unit of the information from another of the service units of the pair of redundant service units, the served unit discarding the information received from the other of the service units of the pair of redundant service units.

A method of operating a redundancy apparatus that comprises a pair of redundant service units each including a copy of a database, a pair of communication media both connected to each service unit, and a plurality of served units, each connected to both communication media and each including a copy of the database, comprising the steps of:

• in response to receipt of information from an information source, a first of the pair of redundant service units storing the received information in its copy of the database and communicating the received information individually to a second of the pair of redundant service units and to each served unit, the first of the pair of redundant service units alternately using a different one of the communication media to communicate the received information to successive ones of the second of the pair of redundant service units and the served units;
• in response to receipt of the information from the first of the pair of redundant service units, the second of the pair of redundant service units storing the received information in its copy of the database and sending an acknowledgment of the receipt to the first of the pair of redundant service units, and communicating the received information individually to each served unit, the second of the pair of redundant service units alternately using a different one of the communication media to communicate the received information to successive ones of the served units;
• in response to receipt of the information from one of the pair of redundant service units, each served unit storing the information received from the one of the pair of redundant service units in its copy of the database and sending an acknowledgment of the receipt across one of the communication media to the one of the redundant pair of service units;
• in response to receipt of the information from another of the pair of redundant service units, each served unit discarding the information received from the other of the pair of redundant service units and sending an acknowledgment of the receipt across one of the media to the other of the pair of redundant service units;
• and
• in response to a failure of either service unit of the pair of redundant service units to receive a timely acknowledgment, of receipt of the information that was communicated by said either service unit, from every served unit and service unit of the pair of redundant service units to which the information was communicated by said either service unit within a predetermined period of time, said either service unit subsequently communicating the information again to any served unit and service unit of the pair of redundant service units to which the information was communicated by said either service unit and from which the acknowledgment was not timely received.