direkt zum Inhalt springen

direkt zum Hauptnavigationsmenü

Sie sind hier

TU Berlin

Inhalt des Dokuments

Peer-to-Peer Computing

Peer-to-peer computing is an interesting networking paradigm as it offers a high degree of scalability by exploiting the resources of the participants and avoids single-points of failures. Due to these desirable properties, peer-to-peer computing plays a crucial role in many networking applications beyond file-sharing, and the underlying ideas are also discussed as a design principle for the future Internet. Our research is concerned with the question of whether peer-to-peer is mature enough to step outside its "comfort zone". We conduct measurements of state-of-the-art peer-to-peer networks such as Kad and investigate the robustness, e.g., to Sybil attacks or selfish behavior. For example, we implemented the proof-of-concept BitTorrent client "BitThief" which provides evidence that despite the tit-for-tat incentive mechanism, free-riding is possible in BitTorrent. We develop algorithms to improve the performance of peer-to-peer systems: we devise peer-to-peer networks which are robust to worst-case churn (see e.g., our IPTPS paper), which allow for efficient joins and leaves (see e.g., our SHELL system at ICALP), or which are robust to denial of service attacks (see e.g., our Chameleon system at SPAA). Some of these algorithms were successfully implemented in the online storage tool Wuala and the streaming tool Streamforge, two Swiss startups.

Selected Publications

On the Topologies Formed by Selfish Peers
Citation key MSW-OTTFBSP-06
Author Moscibroda, Thomas and Schmid, Stefan and Wattenhofer, Roger
Title of Book 25th Annual Symposium on Principles of Distributed Computing (PODC)
Pages 133–142
Year 2006
ISBN 1-59593-384-0
DOI http://dx.doi.org/10.1145/1146381.1146403
Location Denver, Colorado, USA
Month July
Abstract Current peer-to-peer (P2P) systems often suffer from a large fraction of freeriders not contributing any resources to the network. Various mechanisms have been designed to overcome this problem. However, the selfish behavior of peers has aspects which go beyond resource sharing. This paper studies the effects on the topology of a P2P network if peers selfishly select the peers to connect to. In our model, a peer exploits locality properties in order to minimize the latency (or response times) of its lookup operations. At the same time, the peer aims at not having to maintain links to too many other peers in the system. We show that the resulting topologies can be much worse than if peers collaborated. Moreover, the network may never stabilize, even in the absence of churn.
Link to publication Download Bibtex entry

Zusatzinformationen / Extras

Quick Access:

Schnellnavigation zur Seite über Nummerneingabe

Auxiliary Functions