This thesis presents a new design and implementation of the DHash distributed hash table based on erasure encoding. This design is both more robust and more efficient than the previous replication-based implementation [15]. DHash uses

Peer-to-peer (P2P) systems are typically divided into those that centralize lookup functionality in a single location and those that distribute the lookup operation across the set of participating hosts. The former approach can offer constant time lookup latency, but is more expensive to scale and suffers from single points of failure. In contrast, the fully distributed approach is easier to scale and can be more resilient to failures, but the lookup latency scales as a function of the total number of participants. While the research community has made great progress in improving the latency of distributed lookup, these systems, exemplified by Chord[17], typically require O(logN) hops to locate an object in a system with N hosts. In this paper, we explore the costs and benefits of a new hybrid approach that partially distributes lookup information among a dynamically adjusted set of high-capacity "superpeers". This design exploits the resource heterogeneity inherent in existing P2P systems to provide many of the advantages of a centralized system, even while avoiding most of the problems associated with such systems. Lookup is performed using superpeers in constant-time, and the system performs well even in the event of simultaneous superpeer failures. Finally, while our gain in performance is potentially at the expense of scalability, we will show that a straightforward implementation should be able to scale to over one million peers with reasonable lookup rates.

self-organizing substrate for distributed applications and support powerful abstractions such as distributed hash tables (DHTs) and group communication. However, in most of these systems, lack of control over key placement and routing paths raises concerns over autonomy, administrative control and accountability of participating organizations. Additionally, structured p2p overlays tend to assume global connectivity while in reality, network address translation and firewalls limit connectivity among hosts in different organizations. In this paper, we present a general technique that ensures content/path locality and administrative autonomy for participating organizations, and provides natural support for NATs and firewalls. Instances of conventional structured overlays are configured to form a hierarchy of identifier spaces that reflects administrative boundaries and respects connectivity constraints among networks.

Topological considerations are of paramount importance in the design of a P2P lookup service. We present TOPLUS, a lookup service for structured peer-to-peer networks that is based on the hierarchical grouping of peers according to network IP prefixes. TOPLUS is fully distributed and symmetric, in the sense that all nodes have the same role. Packets are routed to their destination along a path that mimics the routerlevel shortest-path, thereby providing a small "stretch". Experimental evaluation confirms that a lookup in TOPLUS takes time comparable to that of IP routing.

PlanetFlow is a network auditing service that maintains comprehensive, permanent accountability for all traffic generated by PlanetLab services, in accordance with common Internet practice and the terms of the PlanetLab Acceptable Use Policy. PlanetFlow audits the usage of PlanetLab network resources in order to facilitate the resolution of complaints, limit liability, and minimize problematic behavior. The current implementation of PlanetFlow consists of a low overhead flow classifier, an autonomously managed distributed database, and a publicly accessible Web interface. PlanetFlow currently processes up to 4 TB of generated traffic per day, and incurs negligible CPU and storage overhead. 1.

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Abstract — Peer-to-peer (P2P) networks have mostly focused on task oriented networking, where networks are constructed for single applications, i.e. file-sharing, DNS caching, etc. In this work, we introduce IPOP, a system for creating virtual IP networks on top of a P2P overlay. IPOP enables seamless access to Grid resources spanning multiple domains by aggregating them into a virtual IP network that is completely isolated from the physical network. The virtual IP network provided by IPOP supports deployment of existing IP-based protocols over a robust, self-configuring P2P overlay. We present implementation details as well as experimental measurement results taken from LAN, WAN, and Planet-Lab tests. I.

Existing empirical studies of Internet structure and path properties indicate that the Internet is tree-like. This work quantifies the degree to which at least two important Internet measures—latency and bandwidth—approximate tree metrics. We evaluate our ability to model end-to-end measures using tree embeddings by actually building tree representations. In addition to being simple and intuitive models, these trees provide a range of commonly-required functionality beyond serving as an analytical tool. The contributions of our study are twofold. First, we investigate the ability to portray the inherent hierarchical structure of the Internet using the most pure and compact topology, trees. Second, we evaluate the ability of our compact representation to facilitate many natural tasks, such as the selection of servers with short latency or high bandwidth from a client. Experiments show that these tasks can be done with high degree of success and modest overhead.

Distributed hash tables have been around for a long time [1, 2]. A number of recent projects propose peer-to-peer DHTs, based on multi-hop lookup optimizations. Some of these systems also require data permanence. This paper presents an analysis of when these optimizations are useful. We conclude that the multi-hop optimizations make sense only for truly vast and very dynamic peer networks. We also observe that resource trends indicate this scale is on the rise.

Abstract. We propose and discuss foundations for programmable overlay networks and overlay computing systems. Such overlays are built over a large number of distributed computational individuals, virtually organized in colonies, and ruled by a leader (broker) who is elected or imposed by system administrators. Every individual asks the broker to log in the colony by declaring the resources that can be offered (with variable guarantees). Once logged in, an individual can ask the broker for other resources. Colonies can recursively be considered as evolved individuals who can log in an outermost colony governed by another super-leader. Communications and routing intra-colonies goes through a broker-2-broker PKI-based negotiation. Every broker routes intra- and inter- service requests by filtering its resource routing table, and then forwarding the request first inside its colony, and second outside, via the proper super-leader (thus applying an endogenous-first-estrogen-last strategy). Theoretically, queries are formulæ in first-order logic equipped with a small program used to orchestrate and synchronize atomic formulæ. When the client individual receives notification of all (or part of) the requested resources, then the real resource exchange is performed directly by the server(s) individuals, without any further mediation of the broker, in a pure peer-to-peer fashion. The proposed overlay promotes an intermittent participation in the colony, since peers can appear, disappear, and organize themselves dynamically. This implies that the routing process may lead to failures, because some individuals have quit, or are temporarily unavailable, or they were logged out manu militari by the broker due to their poor performance or greediness. We design, validate through simulation, and implement these foundations in a programmable overlay computer system, called Arigatoni. “Computer is moving on the edge of the Network...”