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This paper presents an analytical method for evaluating the reliability improvement for any size of multi-computer system based on Software-Implemented Fault-Tolerance (SIFT). The method is based on the equivalent failure rate r, the single node failure rate A, the number of nodes in the system, N, the repair rate Λ, the fault coverage factor c, the reconfiguration rate 6, and the percentage of blocking faults b1 and b2. The impact of these parameters on the reliability improvement has been evaluated for a gracefully degradable multi-computer system using our proposed analytical technique based on Markov chains. To validate our approach, we used the SIFT method which implements error detection at the node level, combined with a fast reconfiguration algorithm for avoiding faulty nodes. It is worth noting that the proposed method is applicable to any multi-computer systems' topology. The evaluation work presented in this paper focuses on the combination of analytical and experimental approaches, and more precisely on Markov chains. The SIFT method has been successfully implemented for a multi-computer system, nCube. The time overhead (reconfiguration & recomputation time) incurred by the injected fault, and the fault coverage factor c, are experimentally evaluated by means of a parallel version of the Software Object-Oriented Fault-Injection Tool (nSOFIT). The implemented SIFT approach can be used for real-time applications, when the time constraints should be met despite failures in the gracefully degradable multi-computer system. [ABSTRACT FROM AUTHOR]

Component failures in high-speed computer networks can result in significant topological changes. In such cases, a network reconfiguration algorithm must be executed to restore the connectivity between the network nodes. Most contemporary networks use either static reconfiguration algorithms or stop the user traffic in order to prevent cyclic dependencies in the routing tables. The goal of this paper is to present NetRec, a dynamic network reconfiguration algorithm for tolerating multiple node and link failures in high-speed networks with arbitrary topology. The algorithm updates the routing tables asynchronously and does not require any global knowledge about the network topology. Certain phases of NetRec are executed in parallel, which reduces the reconfiguration time. The algorithm suspends the application traffic in small regions of the network only while the routing tables are being updated. The message complexity of NetRec is analyzed and the termination, liveness, and safety of the proposed algorithm are proven. Additionally, results from validation of the algorithm in a distributed network-validation testbed Distant, based on the MPI 1.2 features for building arbitrary virtual topologies, are presented. [ABSTRACT FROM AUTHOR]

Introduces a series of articles on fault-tolerant embedded systems.

Discusses algorithms for tolerating faulty nodes and links in hypercubes. Use of general spanning trees, complete unbalanced spanning trees and balanced spanning trees; Phases contained in the algorithms; Basic steps in reconfiguration; Simulation results for the algorithm under more than three faults; Application of the reconfiguration algorithm; Fault tolerance.

Addresses the use of fault injection for explicitly removing design/implementation faults in complex fault-tolerance algorithms and mechanisms (FTAM), viz, fault-tolerance deficiency faults. Introduction of a formalism to represent the FTAM by a set of assertions; Use of the methodology to extend a debugging tool aimed at testing fault tolerance protocols.

Focuses on embedded computer systems. Characteristics of embedded systems; Significance of the system; Technical issues associated with embedded systems.

Introduces a series of articles that cover a wide spectrum of techniques as encountered in the most advanced designs of fault-tolerant embedded systems published in the February 2002 issue of 'IEEE Transactions on Computers.'