20,595 research outputs found
Byzantine-fault tolerant self-stabilizing protocol for distributed clock synchronization systems
A rapid Byzantine self-stabilizing clock synchronization protocol that self-stabilizes from any state, tolerates bursts of transient failures, and deterministically converges within a linear convergence time with respect to the self-stabilization period. Upon self-stabilization, all good clocks proceed synchronously. The Byzantine self-stabilizing clock synchronization protocol does not rely on any assumptions about the initial state of the clocks. Furthermore, there is neither a central clock nor an externally generated pulse system. The protocol converges deterministically, is scalable, and self-stabilizes in a short amount of time. The convergence time is linear with respect to the self-stabilization period
Physics-inspired Performace Evaluation of a Structured Peer-to-Peer Overlay Network
In the majority of structured peer-to-peer overlay networks a graph
with a desirable topology is constructed. In most cases, the graph is
maintained by a periodic activity performed by each node in the graph
to preserve the desirable structure in face of the continuous change
of the set of nodes. The interaction of the autonomous periodic
activities of the nodes renders the performance analysis of such
systems complex and simulation of scales of interest can be
prohibitive. Physicists, however, are accustomed to dealing with
scale by characterizing a system using intensive variables,
i.e. variables that are size independent. The approach has proved its
usefulness when applied to satisfiability theory. This
work is the first attempt to apply it in the area of distributed
systems. The contribution of this paper is two-fold. First, we
describe a methodology to be used for analyzing the performance of
large scale distributed systems. Second, we show how we applied the
methodology to find an intensive variable that describe the
characteristic behavior of the Chord overlay network, namely, the
ratio of the magnitude of perturbation of the network (joins/failures)
to the magnitude of periodic stabilization of the network
Exploiting the Synergy Between Gossiping and Structured Overlays
In this position paper we argue for exploiting the synergy between gossip-based algorithms and structured overlay networks (SON). These two strands of research have both aimed at building fault-tolerant, dynamic, self-managing, and large-scale distributed systems. Despite the common goals, the two areas have, however, been relatively isolated. We focus on three problem domains where there is an untapped potential of using gossiping combined with SONs. We argue for applying gossip-based membership for ring-based SONs---such as Chord and Bamboo---to make them handle partition mergers and loopy networks. We argue that small world SONs---such as Accordion and Mercury---are specifically well-suited for gossip-based membership management. The benefits would be better graph-theoretic properties. Finally, we argue that gossip-based algorithms could use the overlay constructed by SONs. For example, many unreliable broadcast algorithms for SONs could be augmented with anti-entropy protocols. Similarly, gossip-based aggregation could be used in SONs for network size estimation and load-balancing purposes
A framework for proving the self-organization of dynamic systems
This paper aims at providing a rigorous definition of self- organization, one
of the most desired properties for dynamic systems (e.g., peer-to-peer systems,
sensor networks, cooperative robotics, or ad-hoc networks). We characterize
different classes of self-organization through liveness and safety properties
that both capture information re- garding the system entropy. We illustrate
these classes through study cases. The first ones are two representative P2P
overlays (CAN and Pas- try) and the others are specific implementations of
\Omega (the leader oracle) and one-shot query abstractions for dynamic
settings. Our study aims at understanding the limits and respective power of
existing self-organized protocols and lays the basis of designing robust
algorithm for dynamic systems
Self-Correcting Broadcast in Distributed Hash Tables
We present two broadcast algorithms that can be used on top of distributed hash tables (DHTs) to perform group communication and arbitrary queries. Unlike other P2P group communication mechanisms, which either embed extra information in the DHTs or use random overlay networks, our algorithms take advantage of the structured DHT overlay networks without maintaining additional information. The proposed algorithms do not send any redundant messages. Furthermore the two algorithms ensure 100% coverage of the nodes in the system even when routing information is outdated as a result of dynamism in the network. The first algorithm performs some correction of outdated routing table entries with a low cost of correction traffic. The second algorithm exploits the nature of the broadcasts to extensively update erroneous routing information at the cost of higher correction traffic. The algorithms are validated and evaluated in our stochastic distributed-algorithms simulator
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FutureGRID: A Program for long-term research into GRID systems architecture
Proceedings of the 2003 UK e-Science All Hands Meeting, 31st August - 3rd September, Nottingham UKThis is a project to carry out research into long-term GRID architecture, in the University of Cambridge
Computer Laboratory and the Cambridge eScience Center, with support from the Microsoft Research
Laboratory, Cambridge.
It is part of a larger vision for future systems architectures for public computing platforms, including
both scientitic GRID and commodity level computing such as games, peer2peer computing and storage
services and so forth, based on work in the laboratories in recent years into massively scaleable distributed systems for storage, computation, content distribution and collaboration[26]
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