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Sine-Wave Application v2.0. Pavel Čírtek. The Aim of the Work. Create representative prototype of highly dependable synthetic application for TTP/C cluster Perform value-domain fault tolerance tests (every single fault should be tolerated). Definitions.
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Sine-Wave Application v2.0 Pavel Čírtek Sine-Wave Application v2.0
The Aim of the Work • Create representative prototype of highly dependable synthetic application for TTP/C cluster • Perform value-domain fault tolerance tests (every single fault should be tolerated) Sine-Wave Application v2.0
Definitions • TTP/C – Time triggered protocol (fulfils C class of safety requirements) • TDMA – Time Divided Multiple Access • TDMA round – every node has own time slot in one round Sine-Wave Application v2.0
TTP/C node and cluster • Communication Controller (CC) – executes TTP/C protocol • Host Processor (HP) – executes application program • Dual-port CNI (Computer Network Interface) memory – interconnection between CC and HP Sine-Wave Application v2.0
Main goals • Verify that a single fault (transient or permanent) can be tolerated • Test resilience of app. output with regards to more complicated faults (attacking a single node) • Test ability of TTP/C cluster to recover from more complicated faults (attacking more nodes) Sine-Wave Application v2.0
Application work • Get phase shift (S-node) • Compute it through cluster (C-node) • The result phase in A-node should be same as from S-node Sine-Wave Application v2.0
Cluster Schema • S-node – sensor • C-node – computation • A-node – actuator • k – number of C-node pairs • N – number of nodes = 2*k+4 • m – “state memory” Sine-Wave Application v2.0
Cluster timing • Two TDMA rounds • Data frame (N-frame) • Initialization frame (I-frame) • Tasks • TLF (lifesign) – right before sending (in every node) • Two computation tasks – somehow time shifted (in C-nodes) Sine-Wave Application v2.0
Functionality of C-node • Read data di-1 from message • Use data to recalculate state si and new value di • si = f1 (si, di-1) • di = f1 (si, di-1) • Broadcast new value di and si • Four values to compare (two nodes, TTP/C doubled bus) Sine-Wave Application v2.0
Application data • ROM (e.g. constants) • Global data (stored in HP RAM memory) • CNI data (special kind of global data, periodically updated by CC) • Local data (initialized within every run of its task) Sine-Wave Application v2.0
Fault injection • Permanent fault – failed node is fail-silent (only two di in next FTU) • Transient faults: • Global data – four instances of result • Local data – two scenarios: • does not influence the control flow only result (same as global data damaging) • Influences the control flow – TTP/C should recognize it and restart HP Sine-Wave Application v2.0
Conclusion • The aim of model is to use fault injection to evaluate possibilities how to build safety-critical applications. • Improvement of old version – node has its state Sine-Wave Application v2.0