A Hardware Implementation of a Provably Correct Design of a Fault-Tolerant Clock Synchronization Circuit


Book Description

A fault-tolerant clock synchronization system was designed to a proven correct formal specification. Formal methods were used in the development of this specification. A description of the system and an analysis of the tests performed are presented. Plots of typical experimental results are included. Torres-Pomales, Wilfredo Langley Research Center NASA-TM-109001, NAS 1.15:109001 RTOP 505-64-10-10...










A Verified Design of a Fault-Tolerant Clock Synchronization Circuit


Book Description

Schneider demonstrates that many fault tolerant clock synchronization algorithms can be represented as refinements of a single proven correct paradigm. Shankar provides mechanical proof that Schneider's schema achieves Byzantine fault tolerant clock synchronization provided that 11 constraints are satisfied. Some of the constraints are assumptions about physical properties of the system and cannot be established formally. Proofs are given that the fault tolerant midpoint convergence function satisfies three of the constraints. A hardware design is presented, implementing the fault tolerant midpoint function, which is shown to satisfy the remaining constraints. The synchronization circuit will recover completely from transient faults provided the maximum fault assumption is not violated. The initialization protocol for the circuit also provides a recovery mechanism from total system failure caused by correlated transient faults. Miner, Paul S. Langley Research Center ALGORITHMS; CIRCUITS; CLOCKS; FAULT TOLERANCE; SYNCHRONISM; CONVERGENCE; PROTOCOL (COMPUTERS); PROVING; SYSTEM FAILURES...













A Survey of Provably Correct Fault-Tolerant Clock Synchronization Techniques


Book Description

Six provably correct fault-tolerant clock synchronization algorithms are examined. These algorithms are all presented in the same notation to permit easier comprehension and comparison. The advantages and disadvantages of the different techniques are examined and issues related to the implementation of these algorithms are discussed. The paper argues for the use of such algorithms in life-critical applications. Butler, Ricky W. Langley Research Center RTOP 505-66-21-01...







A Survey of Provably Correct Fault-Tolerant Clock Synchronization Techniques


Book Description

Six provably correct fault-tolerant clock synchronization algorithms are examined. These algorithms are all presented in the same notation to permit easier comprehension and comparison. The advantages and disadvantages of the different techniques are examined and issues related to the implementation of these algorithms are discussed. The paper argues for the use of such algorithms in life-critical applications. Butler, Ricky W. Langley Research Center RTOP 505-66-21-01...