TTEthernet Protocol Synchronization. TTEthernet uses a two-step approach to synchronization. In the first step, Synchronization Masters send protocol control frames to compression Masters. The Compression Masters then calculate a fault-tolerant average synchronization value from the relative arrival times of these protocol control frames and send out a new protocol control frame back to the synchronization masters and to other synchronization clients. The Synchronization Masters and Compression Masters can be assigned to devices in any man- ner that meets the requirements for the system. The typical assignment is for (some subset of) the end systems to host the Synchronization Masters and for the switches to host the Compression Masters. End systems exchange application data with each other by transmitting standard Ethernet frames. The points in time when end systems dispatch these frames can be coupled to the synchro- nized time. The transfer of these frames is then called time-triggered transfer, because the trigger 4The SAFEbus drivers and media are not similarly expandable to tolerate additional faults. However, their greater simplicity reduces their probability of generating Byzantine faults. If greater media fault tolerance were ever needed, the ARINC 659 document could be changed to allow additional lanes of media. This would be a simple change to the interface hardware.β 5These numbers are all a multiple of four because SAFEbus uses quadruply redundant media.
Appears in 5 contracts
Samples: ntrs.nasa.gov, ntrs.nasa.gov, ntrs.nasa.gov
