Lucent Technologies Inc.

Gordon Douglas Woods

Peter Allen Dempsey

Douglas Alan Reneker

Ricky Raymond McTee

Klaas Hellenthal

Wai-Ching Yu

Clifford B Stern

A duplex controller with a pair of redundant processor circuits connected by an update bus for use in a system which requires high reliability. Each of the redundant processor circuits is individually capable of performing the tasks of the duplex controller, so that the controller remains operable when one of the processor circuit members fails. The update bus is connected so that when the active circuit member executes a write command, the write command is also effected at the standby circuit. In this manner the memory state of the standby is dynamically maintained so that when control of the duplex controller is transferred from the active to the standby to the standby circuit, the standby circuit is instantaneously ready with up to date information to assume all processing responsibilities of the duplex controller without unnecessary delay.

Duplex processor with an update bus and method for operating the update bus

A method and apparatus for switching from an active to a standby controller in a redundant duplex carrier system without requiring retransmission of messages in progress during the switch. A main processor in the standby controller is periodically switched and made the active controller to ensure reliability of the system. The main processor in the active controller stops sending messages for a period of time before switching control to the standby controller. The main processor in the standby controller delays initiating any new communications until any current messages have been completed from the active controller. The main processor of the standby controller then retrieves any unprocessed messages that may have been sent to the active controller just before or during the switch from the active controller to the standby controller. The delay of new messages and retrieval of any unprocessed messages ensures that no data will be lost during the switch, thus removing the need for retransmission.

Method and apparatus for error free switching in a redundant duplex communication carrier system

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Randolph, NJ, United States of America

Gordon Douglas Woods