Search and replication in unstructured peer-to-peer networks

Peer-to-peer Networking and Applications

Peer-to-Peer networks attracted a significant amount of interest because of their capacity for resource sharing and content distribution. Content distribution applications allow personal computers to function in a coordinated manner as a distributed storage medium by contributing, searching, and obtaining digital content. Searching in unstructured P2P networks is an important problem, which has received considerable research attention. Acceptable searching techniques must provide large coverage rate, low traffic load, and optimum latency. This paper reviews flooding-based search techniques in unstructured P2P networks. It then analytically compares their coverage rate, and traffic overloads. Our simulation experiments have validated analytical results.

Concurrency and Computation: Practice and Experience, 2008

This paper develops a directed generalized random graphs based analytical modeling framework to compare several variations of the basic flooding search strategy in unstructured decentralized peer-topeer networks. To validate the model predictions, we designed and implemented a distributed crawler architecture that is able to efficiently capture snapshots of the top-level Gnutella overlay topology. The snapshots are used to obtain simulation results that are used to assess the accuracy of our model. The model predictions are then used to compute system-oriented performance indexes (the average and the coefficient of variation of the number of query messages) as well as user-oriented measures (the probability of finding at least one replica of a resource, the average search time). The trade-off between the optimization of system-oriented measures and the improvement of user-oriented quality indexes is investigated for several variations of the basic flooding strategy suggesting that adding control parameters to the basic flooding mechanism might prove beneficial in this class of systems.

ACM SIGCOMM Computer Communication Review, 2002

The Peer-to-Peer (P2P) architectures that are most prevalent in today's Internet are decentralized and unstructured. Search is blind in that it is independent of the query and is thus not more effective than probing randomly chosen peers. One technique to improve the effectiveness of blind search is to proactively replicate data.

Proceedings of the eleventh international conference on Information and knowledge management - CIKM '02, 2002

One important problem in peer-to-peer (P2P) networks is searching and retrieving the correct information. However, existing searching mechanisms in pure peer-to-peer networks are inefficient due to the decentralized nature of such networks. We propose two mechanisms for information retrieval in pure peer-to-peer networks. The first, the modified Breadth-First-Search (BFS) mechanism, is an extension of the current Gnuttela protocol, allows searching with keywords, and is designed to minimize the number of messages that are needed to search the network. The second, the Intelligent Search mechanism, uses the past behavior of the P2P network to further improve the scalability of the search procedure. In this algorithm, each peer autonomously decides which of its peers are most likely to answer a given query. The algorithm is entirely distributed, and therefore scales well with the size of the network. We implemented our mechanisms as middleware platforms. To show the advantages of our mechanisms we present experimental results using the middleware implementation.

Network Protocols and Algorithms, 2010

P2P computing lifts taxing issues in various areas of computer science. The largely used decentralized unstructured P2P systems are ad hoc in nature and present a number of research challenges. In this paper, we provide a comprehensive theoretical survey of various state-of-the-art search and replication schemes in unstructured P2P networks for file-sharing applications. The classifications of search and replication techniques and their advantages and disadvantages are briefly explained. Finally, the various issues on searching and replication for unstructured P2P networks are discussed.

2005

The fundamental drawback of unstructured peer-to-peer (P2P) networks is the flooding-based query processing protocol that seriously limits their scalability. As a result, a significant amount of research work has focused on designing efficient search protocols that reduce the overall communication cost. What is lacking, however, is the availability of real data, regarding the exact content of users' libraries and the queries that these users ask. Using trace-driven simulations will clearly generate more meaningful results and further illustrate the efficiency of a generic query processing protocol under a real-life scenario. Motivated by this fact, we developed a Gnutella-style probe and collected detailed data over a period of two months. They involve around 4,500 users and contain the exact files shared by each user, together with any available metadata (e.g., artist for songs) and information about the nodes (e.g., connection speed). We also collected the queries initiated by these users. After filtering, the data were organized in XML format and are available to researchers. Here, we analyze this dataset and present its statistical characteristics. Additionally, as a case study, we employ it to evaluate two recently proposed P2P searching techniques.

2005

Searching for content in peer-to-peer networks is an interesting and challenging problem. Queries in Gnutella-like unstructured systems that use flooding or random walk to search must visit ¢ ¤ £ ¦ ¥ § nodes in a network of size ¥ , thus consuming significant amounts of bandwidth. In this paper, we propose a query routing protocol that allows low bandwidth consumption during query forwarding using a low cost mechanism to create and maintain information about nearby objects. To achieve this, our protocol maintains a lightweight probabilistic routing table at each node that suggests the location of each object in the network. Following the corresponding routing table entries, a query can reach the destination in a small number of hops with high probability. However, maintaining routing tables in a large and highly dynamic network requires non-traditional mechanisms.