| 摘要 |
The invention relates to a method for the reliable switching of synchronisation messages in a distributed computer system consisting of a number of node computers, wherein the management of a transparent clock conforming to IEEE Standard 1588 is supported, wherein a switching unit consists of four separate FCUs, specifically an input system EIN, two independent switching systems VER1 and VER2, and an output system AUS, and wherein a message arriving at EIN from a transmitting node computer is forwarded immediately in unmodified form from EIN directly to the two independent switching systems VER1 and VER2, and wherein VER1 provides the event of the arrival of the message with a timestamp, analyses the message and switches said message to (an) output port(s) associated with an address field of the message, and wherein VER1 opens the message and modifies a TIC field within the message in order to determine the delay period of the message in VER1, and wherein VER1 closes the message again by re-calculating a CRC field of the modified message and forwarding the closed message to AUS, and wherein VER2 provides the event of the arrival of the message with a timestamp, analyses the message and switches said message to the output port(s) associated with the address field of the message, and wherein VER2 opens the message and modifies the TIC field within the message in order to determine the delay period of the message in VER2, and wherein VER2 closes the message again by re-calculating the CRC field of the modified message and forwarding the closed message to AUS, and wherein AUS checks whether the content of the message delivered from VER1 matches the content of the message delivered from VER2, and wherein AUS checks whether the interval between the moment of receipt of the message delivered from VER1 and the moment of receipt of the message delivered from VER2 is smaller than a first interval determined a priori, referred to hereinafter as the interval_1, and whether the absolute value of the difference of the delay values stored in the two TIC fields is smaller than a second interval known a priori, referred to hereinafter as the interval_2, and wherein, in the case that one of these checks is negative, AUS interrupts the transmission of the message that is outbound via the addressed output ports or changes the outbound message in such a way that each message receiver identifies the incoming message as faulty. |
