We propose probabilistic location to enhance the performance of existing peer-to-peer location mechanisms in the case where a replica for the queried data item exists close to the query source. We introduce the attenuated Bloom filter, a lossy distributed index. We describe how to use these data structures for document location and how to maintain them despite document motion. We include a detailed performance study which indicates that our algorithm performs as desired, both finding closer replicas and finding them faster than deterministic algorithms alone. I.

This paper introduces a framework for evaluating replica placement algorithms (RPA) for content delivery networks (CDN) as well as RPAs from other fields that might be applicable to current or future CDNs. First, the framework classifies and qualitatively compares RPAs using a generic set of primitives that capture problem definitions and heuristics. Second, it provides estimates for the decision times of RPAs using an analytic model. To achieve accuracy, the model takes into account disk accesses and message sizes, in addition to computational complexity and message numbers that have been considered traditionally. Third, it uses the "goodness" of produced placements to compare RPAs even when they have different problem definitions. Based on these evaluations, we identify open issues and potential areas for future research.

In the last several years, we have seen a significant amount of work on ad-hoc and peer-to-peer networks. The use of ad-hoc networks occur in a variety of scenarios, but have gained prominence primarily in communications between mobile devices. These include building sensor networks (to monitor activities of various sorts), military communications, vehicular networks, epidemic communication networks [16], and collaboration between mobile devices. The explosive and continuing growth of 802.11 based wireless networks provides the most current impetus for understanding ad-hoc collaboration networks because of its high practical utility. Ad-hoc networks have also been examined for wired (LAN/WAN) scenarios [4, 8, 14, 19] generally in the context of peerto -peer (P2P) computing and more recently in the context of grid computing [18]. For example, research in peer-to-peer (P2P) file-sharing technologies [4, 10] has contributed substantially to ad-hoc network research. This tutorial is intended to examine some of the more sophisticated emerging ad-hoc / P2P networks, their needs and their performance issues.