Results 1  10
of
12
Relating Stabilizing Timing Assumptions to Stabilizing Failure Detectors Regarding Solvability and Efficiency
"... Abstract. We investigate computational models with stabilizing properties. Such models include e.g. the partially synchronous model [Dwork et al. 1988], where after some unknown global stabilization time the system complies to bounds on computing speeds and message delays, or the asynchronous model ..."
Abstract

Cited by 2 (1 self)
 Add to MetaCart
(Show Context)
Abstract. We investigate computational models with stabilizing properties. Such models include e.g. the partially synchronous model [Dwork et al. 1988], where after some unknown global stabilization time the system complies to bounds on computing speeds and message delays, or the asynchronous model augmented with unreliable failure detectors [Chandra et al. 1996], where after some unknown global stabilization time failure detectors stop making mistakes. Using algorithm transformations (a notion we introduce in this paper) we show that many (families of such) models are equivalent regarding solvability. We also analyze the efficiency of such transformations regarding not only the number of steps in a model M1 necessary to emulate a step in a model M2, but also the stabilization shift, which bounds the number of steps in M2 required to provide properties of M2 after the stabilization of M1. 1
Extending Paxos/LastVoting with an Adequate Communication Layer for Wireless Ad hoc Networks
 SYMPOSIUM ON RELIABLE DISTRIBUTED SYSTEMS
, 2008
"... Most papers addressing consensus in wireless ad hoc networks adopt system models similar to those developed for wired networks. These models are focused towards node failures while ignoring link failures, and thus are poorly suited for wireless ad hoc networks. The recently proposed HO model does no ..."
Abstract

Cited by 2 (0 self)
 Add to MetaCart
Most papers addressing consensus in wireless ad hoc networks adopt system models similar to those developed for wired networks. These models are focused towards node failures while ignoring link failures, and thus are poorly suited for wireless ad hoc networks. The recently proposed HO model does not have this drawback. The paper shows that an existing algorithm and the HO model can be used for multihop wireless ad hoc networks, if extended with an adequate communication layer. The description of the communication layer is augmented with simulation results that validate the feasibility of our approach and provide better understanding of the behavior of wireless environments.
Timing Analysis of Leaderbased and Decentralized Byzantine Consensus Algorithms
"... Abstract. We compare in an analytical way two leaderbased and decentralized algorithms (that is, algorithms that do not use a leader) for Byzantine consensus with strong validity. We show that for the algorithms we analyzed, in most cases, the decentralized variant of the algorithm shows a better w ..."
Abstract

Cited by 2 (2 self)
 Add to MetaCart
(Show Context)
Abstract. We compare in an analytical way two leaderbased and decentralized algorithms (that is, algorithms that do not use a leader) for Byzantine consensus with strong validity. We show that for the algorithms we analyzed, in most cases, the decentralized variant of the algorithm shows a better worstcase execution time. Moreover, for the practically relevant case t ≤ 2 (t is the maximum number of Byzantine processes), this worstcase execution time is even at least as good as the execution time of the leaderbased algorithms in faultfree runs. 1
Consensus Refined
"... Abstract—Algorithms for solving the consensus problem are fundamental to distributed computing. Despite their brevity, their ability to operate in concurrent, asynchronous, and failureprone environments comes at the cost of complex and subtle behaviors. Accordingly, understanding how they work and ..."
Abstract

Cited by 2 (0 self)
 Add to MetaCart
(Show Context)
Abstract—Algorithms for solving the consensus problem are fundamental to distributed computing. Despite their brevity, their ability to operate in concurrent, asynchronous, and failureprone environments comes at the cost of complex and subtle behaviors. Accordingly, understanding how they work and proving their correctness is a nontrivial endeavor where abstraction is immensely helpful. Moreover, research on consensus has yielded a large number of algorithms, many of which appear to share common algorithmic ideas. A natural question is whether and how these similarities can be distilled and described in a precise, unified way. In this work, we combine stepwise refinement and lockstep models to provide an abstract and unified view of a sizeable family of consensus algorithms. Our models provide insights into the design choices underlying the different algorithms, and classify them based on those choices. All our results are formalized and verified in the theorem prover Isabelle/HOL, yielding precision and strong correctness guarantees. I.
Solving kset agreement with stable skeleton graphs
 In IPDPS Workshops
, 2011
"... ar ..."
(Show Context)
Consensus in Wireless Ad hoc Networks
, 2008
"... Solving consensus in wireless ad hoc networks has started to be addressed in several papers. Most of these papers adopt system models similar to those developed for wired networks. These models are focused towards node failures while ignoring link failures, and thus are poorly suited for wireless ad ..."
Abstract

Cited by 1 (1 self)
 Add to MetaCart
Solving consensus in wireless ad hoc networks has started to be addressed in several papers. Most of these papers adopt system models similar to those developed for wired networks. These models are focused towards node failures while ignoring link failures, and thus are poorly suited for wireless ad hoc networks. The HO model, which was proposed recently, does not have this drawback. The paper shows that an existing algorithm and the HO model can be used for multihop wireless ad hoc networks, if extended with an adequate communication layer. The description of the communication layer is augmented with simulation results that validate the feasibility of our approach and provide better understanding of the behavior of realistic wireless environments. Research funded by the Swiss National Science Foundation under grant number 200021111701. This is an updated version of the
Consensus when all processes may be Byzantine for some time
"... Among all classes of faults, Byzantine faults form the most general modeling of value faults. Traditionally, in the Byzantine fault model, faults are statically attributed to a set of up to t processes. This, however, implies that in this model a process at which a value fault occurs is forever &qu ..."
Abstract
 Add to MetaCart
(Show Context)
Among all classes of faults, Byzantine faults form the most general modeling of value faults. Traditionally, in the Byzantine fault model, faults are statically attributed to a set of up to t processes. This, however, implies that in this model a process at which a value fault occurs is forever "stigmatized" as being Byzantine, an assumption that might not be acceptable for longlived systems, where processes need to be reintegrated after a fault. We thus consider a model where Byzantine processes can recover in a predefined recovery state, and show that consensus can be solved in such a model.
26th IEEE International Symposium on Reliable Distributed Systems Model Checking of Consensus Algorithms
"... We show for the first time that standard model checking allows one to completely verify asynchronous algorithms for solving consensus, a fundamental problem in faulttolerant distributed computing. Model checking is a powerful verification methodology based on state exploration. However it has rarel ..."
Abstract
 Add to MetaCart
(Show Context)
We show for the first time that standard model checking allows one to completely verify asynchronous algorithms for solving consensus, a fundamental problem in faulttolerant distributed computing. Model checking is a powerful verification methodology based on state exploration. However it has rarely been applied to consensus algorithms, because these algorithms induce huge, often infinite state spaces. Here we focus on consensus algorithms based on the HeardOf model, a new computation model for distributed computing. By making use of the high abstraction level provided by this computation model and by devising a finite representation of unbounded timestamps, we develop a methodology for verifying consensus algorithms in every possible state by model checking. 1.
13th IEEE International Symposium on Pacific Rim Dependable Computing An Automatic RealTime Analysis of the Time to Reach Consensus
"... Consensus is one of the most fundamental problems in faulttolerant distributed computing. This paper proposes a mechanical method for analyzing the condition that allows one to solve consensus. Specifically, we model check a distributed algorithm that implements a communication predicate, which is ..."
Abstract
 Add to MetaCart
(Show Context)
Consensus is one of the most fundamental problems in faulttolerant distributed computing. This paper proposes a mechanical method for analyzing the condition that allows one to solve consensus. Specifically, we model check a distributed algorithm that implements a communication predicate, which is an alternative system abstraction to failure detectors. This model checking problem is challenging because it involves both continuous time and unbounded integers. We solve the problem by reducing it to the satisfiability problem of linear arithmetic constraints over real and integer variables. The proposed method can be used to determine the length of a synchronous period required for implementing a communication predicate for solving consensus. 1.
Swift Algorithms for Repeated Consensus
"... We introduce the notion of a swift algorithm. Informally, an algorithm that solves the repeated consensus is swift if, in a partial synchronous run of this algorithm, eventually no timeout expires, i.e., the algorithm execution proceeds with the actual speed of the system. This definition differs fr ..."
Abstract
 Add to MetaCart
(Show Context)
We introduce the notion of a swift algorithm. Informally, an algorithm that solves the repeated consensus is swift if, in a partial synchronous run of this algorithm, eventually no timeout expires, i.e., the algorithm execution proceeds with the actual speed of the system. This definition differs from other efficiency criteria for partial synchronous systems. Furthermore, we show that the notion of swiftness explains the reason why failure detector based algorithms are typically more efficient than roundbased algorithms, since the former are naturally swift while the later are naturally nonswift. We show that this is not an inherent difference between the models, and provide a round structure implementation that is swift, therefore performing similarly to failure detector algorithms while maintaining the advantages of the round model.