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GLS is a new distributed location service which tracks mobile node locations. GLS combined with geographic forwarding allows the construction of ad hoc mobile networks that scale to a larger number of nodes than possible with previous work. GLS is decentralized and runs on the mobile nodes themselves, requiring no fixed infrastructure. Each mobile node(More)
We describe the design and implementation of Walter, a key-value store that supports transactions and replicates data across distant sites. A key feature behind Walter is a new property called <i>Parallel Snapshot Isolation</i> (PSI). PSI allows Walter to replicate data asynchronously, while providing strong guarantees within each site. PSI precludes(More)
Designing a wide-area distributed hash table (DHT) that provides high-throughput and low-latency network storage is a challenge. Existing systems have explored a range of solutions, including iterative routing, recursive routing, proximity routing and neighbor selection, erasure coding, replication, and server selection. This paper explores the design of(More)
This paper discusses the feasibility of peer-to-peer full-text keyword search of the Web. Two classes of keyword search techniques are in use or have been proposed: flooding of queries over an overlay network (as in Gnutella), and intersection of index lists stored in a distributed hash table. We present a simple feasibility analysis based on the resource(More)
Obtaining user opinion (using votes) is essential to ranking user-generated online content. However, any content voting system is susceptible to the Sybil attack where adversaries can out-vote real users by creating many Sybil identities. In this paper, we present SumUp, a Sybilresilient vote aggregation system that leverages the trust network among users(More)
Recent technological trends indicate that future datacenter networks will incorporate High Performance Computing network features, such as ultra-low latency and CPU bypassing. How can these features be exploited in datacenter-scale systems infrastructure? In this paper, we explore the design of a distributed in-memory key-value store called Pilaf that takes(More)
Today an application developer using a distributed hash table (DHT) with <i>n</i> nodes must choose a DHT protocol from the spectrum between <i>O</i>(1) lookup protocols [9, 18] and <i>O</i>(log <i>n</i>) protocols [20-23, 25, 26]. <i>O</i>(1) protocols achieve low latency lookups on small or low-churn networks because lookups take only a few hops, but(More)
Many applications can see massive speedups by distributing their computation across multiple machines. However, as the number of machines increases, so does the difficulty of writing efficient programs users must tackle the problem of minimizing communication and synchronization performed between hosts while also taking care to be robust against machine(More)
Most existing large-scale networked systems on the Internet such as peer-to-peer systems are vulnerable to Sybil attacks where a single adversary can introduce many bogus identities. One promising defense of Sybil attacks is to perform social-network based admission control to bound the number of Sybil identities admitted. SybilLimit [22], the best known(More)
Protocols for distributed hash tables (DHTs) incorporate features to achieve low latency for lookup requests in the face of churn, continuous changes in membership. These protocol features can include a directed identifier space, parallel lookups, pro-active flooding of membership changes, and stabilization protocols for maintaining accurate routing. In(More)