Team rap

Overall Objectives
Scientific Foundations
New Results
Contracts and Grants with Industry
Other Grants and Activities

Section: New Results

Algorithms: Distributed Hash Tables

Participants : Mathieu Feuillet, Philippe Robert.

The Distributed Hash Tables (DHTs) consist in a large set of nodes connected through the Internet. Each file contained in the DHT is stored in a small subset of these nodes. Each node breaks down periodically and it is necessary to have back-up mechanisms in order to avoid data loss. A trade-off is necessary between the bandwidth and the memory used for this back-up mechanism and the data loss rate. Back-up mechanisms already exist and have been studied thanks to simulation. To our knowledge, no theoretical study does exist on this topic. We modeled this problem thanks to standard queues in order to understand the behavior of a single file and the global dynamic of the system. Different back-up mechanisms are currently under investigation. On the side of this project, we notably studied the distribution of hitting times of the classical Engset model by using martingale techniques, furthermore their asymptotic behavior has been analyzed when the number of nodes in the DHT increases to infinity.


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