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Wide area distributed file systems-A scalability and performance survey

Scalable Computing 2010年第3期11卷 305-326页

作者： Ponnavaikko, Kovendhan Dharanipragada, Janakiram Distributed and Object Systems Lab Department of Computer Science and Engineering Indian Institute of Technology Madras Chennai India

Recent decades have witnessed an explosive growth in the amounts of digital data in various fields of arts, science and engineering. Such data is generally of interest to a large number of people spread over wide geographical areas. Over the years, several distributed File systems (DFS) have, to varying degrees, addressed this requirement of sharing large amounts of data, stored in the form of files, among several users and applications. Scalability and performance are two important measures that determine the suitability of a file system for the applications executing over them. We perform a detailed comparative analysis of popular distributed file systems in terms of these measures in our survey. © 2010 SCPE.

关键词： Surveys

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A testbed-based study of uni- and multi-path Dynamic Source Routing in a WMN

A testbed-based study of uni- and multi-path Dynamic Source ...

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IFIP Wireless Days, WD

作者： Bastian Blywis Mesut Günes David J. H. Gutzmann Felix Juraschek Distributed Embedded Systems Institute of Computer Science Freie Universität Berlin Germany

Dynamic Source Routing (DSR) was one of the first proposed protocols for routing in Mobile Ad-hoc Networks and is among the few that were ratified by the IETF. Despite its source routing overhead, the protocol exhibits particular properties that make it an optimal choice for multi-path routing where multiple paths are discovered for each destination. The alternative paths can either be stored for error recovery situations or used in parallel to improve the throughput. In this paper we present a study of 10 uni- and multi-path DSR variants in a wireless mesh network testbed. A modified ETX metric is proposed for an improved link quality measurement. The experiments are evaluated considering the routing-overhead and packet delivery ratio with focus on the route discovery.

关键词： Routing Routing protocols Unicast Delay Load management

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Gossip routing in wireless mesh networks

Gossip routing in wireless mesh networks

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IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

作者： Bastian Blywis Mesut Güneş Felix Juraschek Sebastian Hofmann Institute of Computer Science - Distributed Embedded Systems Freie Universität Berlin Germany

Gossip routing is an approach to reduce the redundancy of flooding in wireless networks. A study by Haas et al. evaluated different gossip routing variants in simulations on regular and random network topologies. Using the DES-Testbed, a wireless mesh network, we tried to replicate their experiments to evaluate whether the findings hold in real world scenarios. Four different gossip routing variants and the experiment setup are elaborated as well as issues regarding the replication of the experiments discussed. With this study we demonstrate that even small wireless network deployments show a bimodal behavior when a certain probability threshold is passed.

关键词： Lead Floods

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Mechanical decision for a class of integral inequalities

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science China(Information sciences) 2010年第9期53卷 1800-1815页

作者： YANG Lu1,3,YU WenSheng1,2* & YUAN RuYi2 1Shanghai Key Laboratory of Trustworthy Computing,Software Engineering institute,East China Normal University,Shanghai 200062,China 2The Key Laboratory of Complex systems and Intelligence science,institute of Automation,Chinese Academy of sciences,Beijing 100190,China 3Laboratory for Automated Reasoning and programming,Chengdu institute of computer Applications,Chinese Academy of sciences,Chengdu 610041,China 1. Shanghai Key Laboratory of Trustworthy Computing Software Engineering Institute East China Normal University Shanghai 200062 China3. Laboratory for Automated Reasoning and Programming Chengdu Institute of Computer Applications Chinese Academy of Sciences Chengdu 610041 China2. The Key Laboratory of Complex Systems and Intelligence Science Institute of Automation Chinese Academy of Sciences Beijing 100190 China

A class of integral inequalities is transformed into homogeneous symmetric polynomial inequalities beyond Tarski model,where the number of elements of the polynomial,say n,is also a variable and the coefficients are functions of *** is closely associated with some open problems formulated recently by Yang et *** Timofte's dimension-decreasing method for symmetric polynomial inequalities,combined with the inequality-proving package BOTTEMA and a program of implementing the method known as successive difference substitution,we provide a procedure for deciding the nonnegativity of the corresponding polynomial inequality such that the original integral inequality is mechanically decidable;otherwise,a counterexample will be *** effectiveness of the algorithm is illustrated by some more examples.

关键词： integral inequality symmetric polynomial inequality Timofte’s dimension-decreasing method successive difference substitution mechanical decision inequality-proving package BOTTEMA

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Deferring CAPEX Investments in Multi-Layer Networks through IP Traffic-Dependent Expansion Stages

Deferring CAPEX Investments in Multi-Layer Networks through ...

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2010 ITG Symposium on Photonic Networks

作者： Michael Duelli Anke Endler Michael Menth University of Würzburg Institute of Computer Science Chair of Distributed Systems Am Hubland 97074 Germany

Network design is performed for a traffic load in the future. This traffic load is far greater than traffic loads observed at intermediate stages. In this paper, we propose to plan a multi-layer network for such a future traffic load, but instead of provisioning the full network equipment at once, we suggest to defer the deployment of expensive IP interfaces and other enabling equipment only to stages when they are really needed to carry traffic. We develop an algorithm that concentrates IP traffic at an intermediate stage on a subset of those IP interfaces that are required to carry the full load in the future. This reduces the set of used IP interfaces which need to be installed at intermediate stages, and CAPEX investments for the other equipment can be deferred to the future.

关键词： IP networks Topology Network topology Optical switches Multiprotocol label switching Optical fiber networks Algorithm design and analysis

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A service level agreement layer for the D-Grid infrastructure

A service level agreement layer for the D-Grid infrastructur...

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作者： Kuebert, Roland Tenschert, Axel Wäldrich, Oliver Ziegler, Wolfang Battré, Dominic HLRS - High Performance Computing Center Stuttgart Nobelstraße 19 70569 Stuttgart Germany Fraunhofer Institute SCAI Schloss Birlinghoven 53754 Sankt Augustin Germany Technische Universität Berlin Faculty IV - Eletrical Engineering and Computer Science Dept. of Telecommunication Systems Complex and Distributed IT Systems Einsteinufer 17 10587 Berlin Germany

ISBN: (纸本)9781905824212

D-Grid is a German national grid initiative founded by the German Federal Ministry of Education and Research. It provides a frame for the collaboration of researchers across Germany and offers access to distributed services and resources. The SLA4D-Grid project will enhance D-Grid by creating a service level agreement (SLA) layer which is transparently integrated into D-Grid and accessible for the D-Grid community. Copyright © 2010 The Authors.

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Collaborative Measurements of Upload Speeds in P2P systems

Collaborative Measurements of Upload Speeds in P2P Systems

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2010 Proceedings IEEE INFOCOM

作者： John R. Douceur James Mickens Thomas Moscibroda Debmalya Panigrahi Distributed Systems Research Group Microsoft Research Redmond WA Computer Science and Aritificial Intelligence Laboratory Massachusetts Institute of Technology Cambridge MA

ISBN: (纸本)9781424458363

In this paper, we study the theory of collaborative upload bandwidth measurement in peer-to-peer environments. A host can use a bandwidth estimation probe to determine the bandwidth between itself and any other host in the system. The problem is that the result of such a measurement may not necessarily be the sender's upload bandwidth, since the most bandwidth restricted link on the path could also be the receiver's download bandwidth. In this paper, we formally define the bandwidth determination problem and devise efficient distributed algorithms. We consider two models, the free-departure and no-departure model, respectively, depending on whether hosts keep participating in the algorithm even after their bandwidth has been determined. We present lower bounds on the time-complexity of any collaborative bandwidth measurement algorithm in both models. We then show how, for realistic bandwidth distributions, the lower bounds can be overcome. Specifically, we present O(1) and O(log log n)-time algorithms for the two models. We corroborate these theoretical findings with practical measurements on a implementation on PlanetLab.

关键词： Uploading Bandwidth Host systems Lower bound hosts

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DES-SERT: A framework for structured routing protocol implementation

DES-SERT: A framework for structured routing protocol implem...

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2009 2nd IFIP Wireless Days, WD 2009

作者： Blywis, Bastian Güneş, Mesut Juraschek, Felix Schmidt, Philipp Kumar, Pardeep Distributed Embedded Systems Institute of Computer Science Freie Universität Berlin Germany

ISBN: (纸本)9781424456604

Routing is a general task, yet the implementation of routing protocols requires specific operating system related knowledge. The developer has to deal with particular kernel internals that might have severe side effects. This is especially true for reactive and hybrid protocols where routing and forwarding are heavily intermixed. Furthermore, novel routing protocols require features that are not provided by current operating systems or have to be customized. Thus routing protocols for mobile ad-hoc networks and wireless mesh networks are often studied in simulation environments. However, simulations have limitations that can result in conclusions that do not hold in real networks. A framework for the implementation of routing protocols in operating systems is required to enable real world oriented research. We introduce the DES Simple and Extensible Routing-Framework for Testbeds (DES-SERT). The framework supports the implementation and evaluation of routing protocols in a testbed environment. A structured protocol implementation is advocated by transmitting data in extensions attached to packets and by its pipeline based architecture. Several steps are elaborated how to derive an implementation from a routing protocol specification. ©2009 IEEE.

关键词： Testbeds

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Instant-X: Towards a generic API for multimedia middleware

Instant-X: Towards a generic API for multimedia middleware

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2009 IEEE International Conference on Internet Multimedia Services Architecture and Applications, IMSAA 2009

作者： Elsholz, Jan-Patrick Schmidt, Holger Schober, Sven Hauck, Franz J. Kassler, Andreas Institute of Distributed Systems Ulm University Germany Computer Science Department Karlstads Universitet Sweden

ISBN: (纸本)9781424447923

The globalisation of our society leads to an increasing need for spontaneous communication. However, the development of such applications is a tedious and error-prone process. This results from the fact that in general only basic functionality is available in terms of protocol implementations and encoders/decoders. This leads to inflexible proprietary software systems implementing unavailable functionality on their own. In this work we introduce Instant-X, a novel component-based middleware platform for multimedia applications. Unlike related work, Instant-X provides a generic programming model with an API for essential tasks of multimedia applications with respect to signalling and data transmission. This API abstracts from concrete component implementations and thus allows replacing specific protocol implementations without changing the application code. Furthermore, Instant-X supports dynamic deployment, i.e., unavailable components can be automatically loaded at runtime. To show the feasibility of our approach we evaluated our Instant-X prototype regarding code complexity and performance. ©2009 IEEE.

关键词： Middleware

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Spontaneous and privacy-friendly mobile indoor routing and navigation

Spontaneous and privacy-friendly mobile indoor routing and n...

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39th Jahrestagung der Gesellschaft fur Informatik e.V. (GI): Im Focus das Leben, INFORMATIK 2009

作者： Ruppel, Peter Gschwandtner, Florian Mobile and Distributed Systems Group Institute for Computer Science Ludwig-Maximilians-Universität Munich Germany

ISBN: (纸本)9783885792482

Mobile indoor navigation systems guide users through buildings and premises by taking into account the current position of the user and a destination such as a room, office or shop. In many environments a spontaneous and also anonymous navigation is desirable e.g. at airports, hospitals or university campuses. However, many systems that have been proposed so far require the integration of a radio-based positioning system and access to other organization-specific systems, which results in a lot of things a user has to deal with before the navigation system can be used and which raises a lot of issues with respect to the location privacy of the user. In this paper we propose a mobile indoor navigation system that allows spontaneous navigation and that guarantees location privacy for the user. A pre-compiled compact representation for all the routes and navigation instructions in a building is the basis for an application that uses the built-in camera on the mobile device to derive the current position in the building from barcodes which are distributed all over the building. We show that the approach allows to navigate through a building with thousands of rooms and requires only little data on the device. Routes can be computed efficiently in O(1) on the device and the only infrastructure that is required are the barcodes which can be easily printed and installed at walls or already existing signs in the building.

关键词： Buildings

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