Institut für Verteilte Systeme

Unser Institut beschäftigt sich mit Themen wie Skalierbarkeit, Zuverlässigkeit, Sicherheit und Datenschutz, Selbstorganisation und Beherrschbarkeit von Komplexität in Verteilten Systemen in einer Vielzahl von Einsatzszenarien wie Cloud-Computing oder Fahrzeug-Fahrzeug-Kommunikation.

In der Lehre decken wir das gesamte Spektrum von Rechnernetzen, über verteilte Systeme bis hin zu Sicherheit und Privacy-Schutz ab.


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Unsere letzten Publikationen

Erb, Benjamin; Kargl, Frank
Chronograph–A Distributed Platform for Event-Sourced Graph Computing
Proceedings of the Posters and Demos Session of the 17th International Middleware Conference
Dezember 2016


Zusammenfassung: Many data-driven applications require mechanisms for processing interconnected or graph-based data sets. Several platforms exist for offline processing of such data and fewer solutions address online computations on dynamic graphs. We combined a modified actor model, an event-sourced persistence layer, and a vertex-based, asynchronous programming model in order to unify event-driven and graph-based computations. Our distributed chronograph platform supports both near-realtime and batch computations on dynamic, event-driven graph topologies, and enables full history tracking of the evolving graphs over time.

Kopp, Henning; Bösch, Christoph; Kargl, Frank
KopperCoin -- A Distributed File Storage with Financial Incentives
Herausgeber: Springer,
November 2016

Zusammenfassung: One of the current problems of peer-to-peer-based file storage systems like Freenet is missing participation, especially of storage providers. Users are expected to contribute storage resources but may have little incentive to do so. In this paper we propose KopperCoin, a token system inspired by Bitcoin’s blockchain which can be integrated into a peer-to-peer file storage system. In contrast to Bitcoin, KopperCoin does not rely on a proof of work (PoW) but instead on a proof of retrievability (PoR). Thus it is not computationally expensive and instead requires participants to contribute file storage to maintain the network. Participants can earn digital tokens by providing storage to other users, and by allowing other participants in the network to download files. These tokens serve as a payment mechanism. Thus we provide direct reward to participants contributing storage resources.

Lukaseder, Thomas; Bradatsch, Leonard; Erb, Benjamin; van der Heijden, Rens W.; Kargl, Frank
A Comparison of TCP Congestion Control Algorithms in 10G Networks
Proceedings of the 41st IEEE Conference on Local Computer Networks (LCN)
November 2016

Schlüsselwörter: BWNET

Marker: BWNET

Zusammenfassung: The increasing availability of 10G Ethernet network capabilities challenges existing transport layer protocols. As 10G connections gain momentum outside of backbone networks, the choice of appropriate TCP congestion control algorithms becomes even more relevant for networked applications running in environments such as data centers. Therefore, we provide an extensive overview of relevant TCP congestion control algorithms for high-speed environments leveraging 10G. We analyzed and evaluated six TCP variants using a physical network testbed, with a focus on the effects of propagation delay and significant drop rates. The results indicate that of the algorithms compared, BIC is most suitable when no legacy variant is present; CUBIC is suggested otherwise.

Lukaseder, Thomas; Bradatsch, Leonard; Erb, Benjamin; Kargl, Frank
Setting Up a High-Speed TCP Benchmarking Environment—Lessons Learned
Proceedings of the 41st IEEE Conference on Local Computer Networks (LCN)
November 2016

Schlüsselwörter: BWNET

Marker: BWNET

Zusammenfassung: There are many high-speed TCP variants with different congestion control algorithms, which are designed for specific settings or use cases. Distinct features of these algorithms are meant to optimize different aspects of network performance, and the choice of TCP variant strongly influences application performance. However, setting up tests to help with the decision of which variant to use can be problematic, as many systems are not designed to deal with high bandwidths, such as 10 Gbps or more. This paper provides an overview of pitfalls and challenges of realistic network analysis to help in the decision making process.

Meißner, Dominik; Erb, Benjamin; van der Heijden, Rens W.; Lange, Kristin; Kargl, Frank
Mobile Triage Management in Disaster Area Networks Using Decentralized Replication
Proceedings of the Tenth ACM MobiCom Workshop on Challenged Networks
Oktober 2016

Zusammenfassung: In large-scale disaster scenarios, efficient triage management is a major challenge for emergency services. Rescue forces traditionally respond to such incidents with a paper-based triage system, but technical solutions can potentially achieve improved usability and data availability. We develop a triage management system based on commodity hardware and software components to verify this claim. We use a single-hop, ad-hoc network architecture with multi-master replication, a tablet-based device setup and a mobile application for emergency services. We study our system in cooperation with regional emergency services and describe experiences from a field exercise. We show that state-of-the-art commodity technology provides the means necessary to implement a triage management system compatible with existing emergency service procedures, while introducing additional benefits. This work highlights that powerful real-world ad-hoc networking applications do not require unreasonable development effort, as existing tools from distributed systems, like replicating No-SQL databases, can be used successfully.

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