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We assume that a message may be delivered by packets through multiple hops and investigate the feasibility and efficiency of an Omega Failure Detector implementation. To motivate the study, we prove the existence and sustainability of a leader is exponentially more probable in a multi-hop than in a single-hop implementation. An implementation is: message efficient if all but finitely many messages are sent by a single process; packet efficient if it is message efficient and the number of packets used to transmit all but finitely many messages is proportional to the number of processes in the system; super packet efficient if it is message efficient and the number of channels used to transmit all but finitely many packets is proportional to the number of processes in the system. We prove that a super packet efficient implementation of Omega is impossible. We establish necessary conditions for the existence of a packet efficient implementation of Omega and present an algorithm that implements Omega under these conditions. [ABSTRACT FROM AUTHOR]

Self-stabilization is a versatile approach to fault-tolerance since it permits a distributed system to recover from any transient fault that arbitrarily corrupts the contents of all memories in the system. Byzantine tolerance is an attractive feature of distributed systems that permits to cope with arbitrary malicious behaviors. This paper focuses on systems that are both self-stabilizing and Byzantine tolerant. Combining these two properties is known to induce many impossibility results. Hence, there exist several fault tolerance schemes to contain Byzantine faults in self-stabilization. In this paper, we consider the well known problem of constructing a maximum metric tree in this context. We provide a new distributed protocol that ensures the best possible containment with respect to topology-aware strict and strong stabilization. [ABSTRACT FROM AUTHOR]

We consider the problem of reliably broadcasting a message in a multihop network. We assume that some nodes may be Byzantine, and behave arbitrarily. We focus on cryptography-free solutions. We propose a protocol for sparse networks (such as grids or tori) where the nodes are not aware of their position. Our protocol uses a fixed number of disjoint paths to accept and forward the message to be broadcast. It can be tuned to significantly improve the number of Byzantine nodes tolerated. We present both theoretical analysis and experimental evaluation. [ABSTRACT FROM AUTHOR]

We present fault detectors for transient faults, (i.e., corruptions of the memory of the processors, but not of the code of the processors). We distinguish fault detectors for tasks (i.e., the problem to be solved) from failure detectors for implementations (i.e., the algorithm that solves the problem). The aim of our fault detectors is to detect a memory corruption as soon as possible. We study the amount of memory needed by the fault detectors for some specific tasks, and give bounds for each task. The amount of memory is related to the size and the number of views that a processor has to maintain to ensure a quick detection. This work may give the implementation designer hints concerning the techniques and resources that are required for implementing a task. [ABSTRACT FROM AUTHOR]

Fault tolerance is a crucial property for recent distributed systems. We propose an algorithm that solves the census problem (list all processor identifiers and their relative distance) on an arbitrary strongly connected network.This algorithm tolerates transient faults that corrupt the processors and communication links memory (it is self-stabilizing) as well as intermittent faults (fair loss, reorder, finite duplication of messages) on communication media. A formal proof establishes its correctness for the considered problem. Our algorithm leads to the construction of algorithms for any silent problems that are self-stabilizing while supporting the same communication hazards. [Copyright &y& Elsevier]

Hierarchical routing provides a less expensive algorithm compared to the traditional all-pairs routing algorithms. We present an algorithm in this paper which benefits from the lower memory requirement, faster routing table lookup, and less costly broadcast exemplified by hierarchical routing, and yet maintains routing capability of all pairs of connected nodes even in the presence of faults, such as link/node failures and repairs, and corruption of program variables. Additionally, this algorithm solves the problem of cluster partitioning where nodes that are supposed to be in the same subset of the network, become isolated due to link or node failures. Being self-stabilizing, starting from an arbitrary state (with possibly corrupted routing tables), the protocol is guaranteed to reach a configuration with routing tables containing valid entries in a finite time. The protocol automatically updates the shortest paths in the face of dynamically changing link weights. The proposed protocol also dynamically allocates/deallocates storage for the routing information as the network size changes. The algorithm works on an arbitrary topology and under a distributed daemon model. [ABSTRACT FROM AUTHOR]

We revisit Byzantine-tolerant reliable broadcast with honest dealer algorithms in multi-hop networks. To tolerate Byzantine faulty nodes arbitrarily spread over the network, previous solutions require a factorial number of messages to be sent over the network if the messages are not authenticated (e.g., digital signatures are not available). We propose modifications that preserve the safety and liveness properties of the original unauthenticated protocols, while highly decreasing their observed message complexity when simulated on several classes of graph topologies, potentially opening to their employment. [ABSTRACT FROM AUTHOR]

We study theoretical and practical aspects of five of the most well-known self-stabilizing dining philosophers algorithms. We theoretically prove that three of them are incorrect. For practical evaluation, we simulate these five algorithms as well as two classic non-self-stabilizing algorithms and evaluate their fault-tolerance, latency and throughput of critical section access. We present a new combined algorithm that achieves the best throughput of the two remaining correct self-stabilizing algorithms by determining the system load and switching between these basic algorithms. We prove the combined algorithm correct, simulate it and study its performance characteristics. [ABSTRACT FROM AUTHOR]

A fault-tolerant and practically stabilizing simulation of an atomic register is presented. The simulation works in asynchronous message-passing systems, and allows a minority of processes to crash. The simulation stabilizes in a practically stabilizing manner, by reaching a long execution in which it runs correctly. A key element in the simulation is a new combinatorial construction of a bounded labeling scheme accommodating arbitrary labels, including those not generated by the scheme itself. [ABSTRACT FROM AUTHOR]