Broadcasting in Prefix Space: P2P Data Dissemination with Predictable Performance

A broadcast mode may augment peer-to-peer overlay networks with an efficient, scalable data replication function, but may also give rise to a virtual link layer in VPN-type solutions. We introduce a simple broadcasting mechanism that operates in the prefix space of distributed hash tables without signaling. This paper concentrates on the performance analysis of the prefix flooding scheme. Starting from simple models of recursive $k$-ary trees, we analytically derive distributions of hop counts and the replication load. Extensive simulation results are presented further on, based on an implementation within the OverSim framework. Comparisons are drawn to Scribe, taken as a general reference model for group communication according to the shared, rendezvous-point-centered distribution paradigm. The prefix flooding scheme thereby confirmed its widely predictable performance and consistently outperformed Scribe in all metrics. Reverse path selection in overlays is identified as a major cause of performance degradation.Comment: final version for ICIW'0

Content-based addressing in hierarchical distributed hash tables

Peer-to-peer networks have drawn their strength from their ability to operate functionally without the use of a central agent. In recent years the development of the structured peer-to-peer network has further increased the distributed nature of p2p systems. These networks take advantage of an underlying distributed data structure, a common one is the distributed hash table (DHT). These peers use this structure to act as equals in a network, sharing the same responsibilities of maintaining and contributing. But herein lays the problem, not all peers are equal in terms of resources and power. And with no central agent to monitor and balance load , the heterogeneous nature of peers can cause many distribution or bottleneck issues on the network and peer levels. This is due to the way in which addresses are allocated in these DHTs. Often this function is carried out by a consistent hashing function. These functions although powerful in their simplicity and effectiveness are the stem of a crucial flaw. This flaw causes the random nature in which addresses are assigned both when considering peer identification and allocating resource ownership. This work proposes a solution to mitigate the random nature of address assignment in DHTs, leveraging two methodologies called hierarchical DHTs and content based addressing. Combining these methods would enable peers to work in cooperative groups of like interested peers in order to dynamically share the load between group members. Group formation and utilization relies on the actual resources a peer willingly shares and is able to contribute rather than a function of the random hash employed by traditional DHT p2p structures

File management in a mobile DHT-based P2P environment

The emergence of mobile P2P systems is largely due to the evolution of mobile devices into powerful information processing units. The relatively structured context that results from the mapping of mobile patterns of behaviour onto P2P models is however constrained by the vulnerabilities of P2P networks and the inherent limitations of mobile devices. Whilst the implementation of P2P models gives rise to security and reliability issues, the deployment of mobile devices is subject to efficiency constraints. This paper presents the development and deployment of a mobile P2P system based on distributed hash tables (DHT). The secure, reliable and efficient dispersal of files is taken as an application. Reliability was addressed by providing two methods for file dispersal: replication and erasure coding. Security constraints were catered for by incorporating an authentication mechanism and three encryption schemes. Lightweight versions of various algorithms were selected in order to attend to efficiency requirements

Scalable adaptive group communication on bi-directional shared prefix trees

Efficient group communication within the Internet has been implemented by multicast. Unfortunately, its global deployment is missing. Nevertheless, emerging and progressively establishing popular applications, like IPTV or large-scale social video chats, require an economical data distribution throughout the Internet. To overcome the limitations of multicast deployment, we introduce and analyze BIDIR-SAM, the rest structured overlay multicast scheme based on bi-directional shared prefix trees. BIDIR-SAM admits predictable costs growing logarithmically with increasing group size. We also present a broadcast approach for DHT-enabled P2P networks. Both schemes are integrated in a standard compliant hybrid group communication architecture, bridging the gap between overlay and underlay as well as between inter- and intra-domain multicast

Internet-scale storage systems under churn - a study of the steady state using markov models

Markov model

Do you feel a chill? Using PIR against chilling effects for censorship-resistant publishing

Peer-to-peer distributed hash tables (DHTs) rely on volunteers to contribute their computational resources, such as disk space and bandwidth. In order to incentivize these node operators of privacy-preserving DHTs, it is important to prevent exposing them to the data that is stored on the DHT and/or queried for. Vasserman et al.\u27s CROPS aimed at providing plausible deniability to server nodes by encrypting stored content. However, node operators are still exposed to the contents of queries. We provide an architecture that uses information-theoretic private information retrieval to efficiently render a server node incapable of determining what content was retrieved in a given request by a user. We illustrate an integration of our architecture with the aforementioned system. Finally, we simulate our system and show that it has a small communication and performance overhead over other systems without this privacy guarantee, and smaller overheads with respect to the closest related work

Position-relative identities in the internet of things: An evolutionary GHT approach

The Internet of Things (IoT) will result in the deployment of many billions of wireless embedded systems creating interactive pervasive environments. It is envisaged that devices will cooperate to provide greater system knowledge than the sum of its parts. In an emergency situation, the flow of data across the IoT may be disrupted, giving rise to a requirement for machine-to-machine interaction within the remaining ubiquitous environment. Geographic hash tables (GHTs) provide an efficient mechanism to support fault-tolerant rendezvous communication between devices. However, current approaches either rely on devices being equipped with a GPS or being manually assigned an identity. This is unrealistic when the majority of these systems will be located inside buildings and will be too numerous to expect manual configuration. Additionally, when using GHT as a distributed data store, imbalance in the topology can lead to storage and routing overhead. This causes unfair work load, exhausting limited power supplies as well as causing poor data redundancy. To deal with these issues, we propose an approach that balances graph-based layout identity assignment, through the application of multifitness genetic algorithms. Our experiments show through simulation that our multifitness evolution technique improves on the initial graph-based layout, providing devices with improved balance and reachability metrics

A Comparative Study of Rateless Codes for P2P Persistent Storage

International audienceThis paper evaluates the performance of two seminal rateless erasure codes, LT Codes and Online Codes. Their properties make them appropriate for coping with communication channels having an unbounded loss rate. They are therefore very well suited to peer-to-peer systems. This evaluation targets two goals. First, it compares the performance of both codes in different adversarial environments and in different application contexts. Second, it helps understanding how the parameters driving the behavior of the coding impact its complexity. To the best of our knowledge, this is the first comprehensive study facilitating application designers in setting the optimal values for the coding parameters to best fit their P2P context

Effects of Data Replication on Data Exfiltration in Mobile Ad hoc Networks Utilizing Reactive Protocols

A swarm of autonomous UAVs can provide a significant amount of ISR data where current UAV assets may not be feasible or practical. As such, the availability of the data the resides in the swarm is a topic that will benefit from further investigation. This thesis examines the impact of le replication and swarm characteristics such as node mobility, swarm size, and churn rate on data availability utilizing reactive protocols. This document examines the most prominent factors affecting the networking of nodes in a MANET. Factors include network routing protocols and peer-to-peer le protocols. It compares and contrasts several open source network simulator environments. Experiment implementation is documented, covering design considerations, assumptions, and software implementation, as well as detailing constant, response and variable factors. Collected data is presented and the results show that in swarms of sizes of 30, 45, and 60 nodes, le replication improves data availability until network saturation is reached, with the most significant benefit gained after only one copy is made. Mobility, churn rate, and swarm density all influence the replication impact