This paper presents Virtual Ring Routing (VRR), a new network routing protocol that occupies a unique point in the design space. VRR is inspired by overlay routing algorithms in Distributed Hash Tables (DHTs) but it does not rely on an underlying network routing protocol. It is implemented directly on top of the link layer. VRR provides both traditional point-to-point network routing and DHT routing to the node responsible for a hash table key. VRR can be used with any link layer technology but this paper describes a design and several implementations of VRR that are tuned for wireless networks. We evaluate the performance of VRR using simulations and measurements from a sensor network and an 802.11a testbed. The experimental results show that VRR provides robust performance across a wide range of environments and workloads. It performs comparably to, or better than, the best wireless routing protocol in each experiment. VRR performs well because of its unique features: it does not require network flooding or translation between fixed identifiers and location-dependent addresses.

The “conversion rate” of spam — the probability that an unsolicited e-mail will ultimately elicit a “sale ” — underlies the entire spam value proposition. However, our understanding of this critical behavior is quite limited, and the literature lacks any quantitative study concerning its true value. In this paper we present a methodology for measuring the conversion rate of spam. Using a parasitic infiltration of an existing botnet’s infrastructure, we analyze two spam campaigns: one designed to propagate a malware Trojan, the other marketing on-line pharmaceuticals. For nearly a half billion spam e-mails we identify the number that are successfully delivered, the number that pass through popular anti-spam filters, the number that elicit user visits to the advertised sites, and the number of “sales” and “infections” produced.

An efficient name resolution scheme is the cornerstone of any peer-to-peer network. The foundation of an efficient name resolution scheme is a dynamic network topology that determines the neighbor relationships to be maintained by the nodes in the network. The name resolution scheme proposed by Plaxton, Rajaraman, and Richa, which we hereafter refer to as the PRR scheme, is a scalable scheme that also provides provable locality properties on a certain class of growth-restricted metric spaces. On arbitrary metric spaces, however, some performance bounds of PRR are significantly weakened. In this paper, we define a class of network topologies called hyperdelta networks and observe that the PRR topology may be viewed as a random hyperdelta network. We then propose SPRR (simplified PRR), a variant of the PRR scheme that performs well on arbitrary metric spaces. SPRR imposes additional constraints on PRR neighbor selection by placing the nodes on a cycle. Although SPRR does not provide as strong locality properties as PRR, it exploits locality heuristically yet effectively. Finally, a significant level of fault tolerance can be achieved in SPRR without adding much complexity.

Important research efforts are being conducted in the area of search, lookup, and routing, and are even increasing in the quest for P2P middleware that is both scalable and decentralized. To structure and classify current as well as to facilitate and give direction to future research, this methodology proposes a top-down two-dimensional design space. This design space has been developed for exhaustiveness so as to cover all possible design options, existing or yet to be conceived. A comprehensive survey of P2P search systems serves as a reference for the reader while at the same time validating the framework. An identification of areas in the design space not being covered by current systems leads to the design of a novel peer-to-peer-based keyword routing scheme. Finally, an evaluation of possible design options along the most important requirements will help guide system designers.

Abstract — In this paper, we investigate the problem of highly available, massive-scale file distribution in the Internet. To this end, we conduct a large-scale measurement study of BitTorrent, a popular class of systems that use swarms of actively downloading peers to assist each other in file distribution. The first generation of BitTorrent systems used a central tracker to enable coordination among peers, resulting in low availability due to the tracker’s single point of failure. Our study analyzes the prevalence and impact of two recent trends to improve BitTorrent availability: (i) use of multiple trackers, and (ii) use of Distributed Hash Tables (DHTs), both of which also help to balance load better. The study considered more than 1,400 trackers and 24,000 DHT nodes (extracted from about 20,000 torrents) over a period of two months. We find that both trends improve availability, but for different and somewhat unexpected reasons. Our findings include: (i) multiple trackers improve availability, but the improvement largely comes from the choice of a single highly available tracker, (ii) such improvement is reduced by the presence of correlated failures, (iii) multiple trackers can significantly reduce the connectivity of the overlay formed by peers, (iv) the DHT improves information availability, but induces a higher response latency to peer queries. I.

Abstract—Content-based routing (CBR) is becoming increasingly popular as a building block for distributed applications. CBR differs from classical routing paradigms as messages are routed based on their content rather than their destination address, which fosters decoupling and flexibility in the application’s distributed architecture. However, most available systems realize CBR by relying on a tree-shaped overlay network and adopt a routing strategy based on broadcasting subscription requests, thus hampering applicability in very large-scale networks. In this paper, we observe that a fundamental underpinning of any CBR protocol is for messages and subscriptions to “meet” at some points in the network. In the approach we propose here, called HyperCBR 1, we enforce this topological property in a multidimensional space, by routing messages and subscriptions on different, albeit intersecting, partitions. We derive an analytical model of HyperCBR, validated through simulation, and use it to evaluate our approach in two relevant CBR contexts— content-based searches in peer-to-peer networks, and contentbased publish-subscribe. The results show that our protocol achieves efficient CBR even in very large scale settings (e.g., millions of nodes) while at the same time opening up intriguing opportunities for deployment-time tuning based on the expected traffic profiles. The analytical evaluation is complemented by simulation results relying on a CAN-based implementation, showing that HyperCBR generates a small forwarding and matching load, and that it is able to tolerate high churn with low overhead. I.

Abstract—The Internet has become a cost-effective vehicle for software development and release, particular in the free software community. Given the free nature of this software, there are often a number of users motivated by altruism to help out with the distribution, so as to promote the healthy development of this voluntary society. It is thus naturally expected that a peer-topeer distribution can be implemented, which will scale well with large user bases, and can easily explore the network resources made available by the volunteers. Unfortunately, this application scenario has many unique characteristics, which make a straightforward adoption of existing peer-to-peer systems for file sharing (such as BitTorrent) suboptimal. In particular, a software release often consists of a large number of packages, which are difficult to distribute individually, but the archive is too large to be distributed in its entirety. The packages are also being constantly updated by the loosely-managed developers, and the interest in a particular version of a package can be very limited depending on the computer platforms and operating systems used. In this paper, we propose a novel peer-to-peer assisted distribution system design that addresses the above challenges. It enhances the existing distribution systems by providing compatible and yet more efficient downloading and updating services for software packages. Our design leads to apt-p2p, a practical implementation that extends the popular apt distributor. apt-p2p has been used in conjunction with Debian-based distribution of Linux software packages and is also available in the latest release of Ubuntu. We have addressed the key design issues in apt-p2p, including indexing table customization, response time reduction, and multi-value extension. They together ensure that the altruistic users ’ resources are effectively utilized and thus significantly reduces the currently large bandwidth requirements of hosting the software, as confirmed by our existing real user statistics gathered over the Internet. I.

Abstract—This paper presents a design for a general locality preserving routing overlay network based on geographic coordinates of nodes. For efficient use of network resources, it is important to follow some locality principles while routing bulk multimedia content. The proposed overlay network creates the interconnection among large number of highly dynamic nodes in a completely decentralized manner, based on adaptive hierarchical partitioning of the geographical space. A major benefit of using coarse grain geographic coordinates is that they are available at off-the-shelf databases and thus do not incur additional measurement overhead. The performance of the proposed geography based routing overlay, in terms of two locality properties – stretch and route-convergence, is evaluated by simulation studies. Real topology data of 65 ISPs with presence in 534 cities across the world, collected by the RocketFuel project, is used as the basis of the simulated network. The performance results are compared with corresponding results obtained from a simulated Pastry overlay constructed on the same underlying network. The performance results show that proposed overlay has significantly better stretch and route-convergence characteristics compared to a regular Pastry network. The locality properties of the proposed routing overlay are almost equivalent to those of an optimal Pastry network where all nodes use the most proximal neighbor for each routing table row. Thus the proposed geographical routing network provides good locality properties without the overhead of proximity neighbor selection. Moreover, the proposed scheme facilitates certain geographical search applications that are difficult to realize in a Pastry overlay. I.