OBST: A self-adjusting peer-to-peer overlay based on multiple BSTs (original) (raw)
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Scaling Unstructured Peer-to-Peer Networks With Multi-Tier Capacity-Aware Overlay Topologies
The peer to peer (P2P) file sharing systems such as Gnutella have been widely acknowledged as the fastest growing Internet applications ever. The P2P model has many potential advantages due to the design flexibility of overlay networks and the serverless management of cooperative sharing of information and resources. However, these systems suffer from the well-known performance mismatch between the randomly constructed overlay network topology and the underlying IP layer topology for packet routing. This paper proposes to structure the P2P overlay topology using a capacity-aware multi-tier topology to better balance load at peers with heterogeneous capacities and to prevent low capacity nodes from downgrading the performance of the system. An analytical model is developed to enable us to construct and maintain capacity-aware overlay topologies with good node connectivity and better load balance. To study the benefits and cost of the multi-tier capacity aware topology with respect to basic and advanced routing protocols, we also develop a probabilistic broadening scheme for efficient routing, which further utilizes capacity-awareness to enhance the P2P routing performance of the system. We evaluate our design through simulations. The results show that our multi-tier topologies alone can provide eight to ten times improvements in the messaging cost, two to three orders of magnitude improvement in terms of load balancing characteristics, and seven to eight times lower topology construction and maintenance costs when compared to Gnutellas random power-law topology.
Efficient Routing for Peer-to-Peer Overlays
2004
Most current peer-to-peer lookup schemes keep a small amount of routing state per node, typically logarithmic in the number of overlay nodes. This design assumes that routing information at each member node must be kept small, so that the bookkeeping required to respond to system membership changes is also small, given that aggressive membership dynamics are expected. As a consequence, lookups have high latency as each lookup requires contacting several nodes in sequence.
Limited Scale-Free Overlay Topologies for Unstructured Peer-to-Peer Networks
Parallel and Distributed Systems, IEEE …, 2009
In unstructured peer-to-peer (P2P) networks, the overlay topology (or connectivity graph) among peers is a crucial component in addition to the peer/data organization and search. Topological characteristics have profound impact on the efficiency of a search on such unstructured P2P networks, as well as other networks. A key limitation of scale-free (power-law) topologies is the high load (i.e., high degree) on a very few number of hub nodes. In a typical unstructured P2P network, peers are not willing to maintain high degrees/loads as they may not want to store a large number of entries for construction of the overlay topology. Therefore, to achieve fairness and practicality among all peers, hard cutoffs on the number of entries are imposed by the individual peers, which limits scale-freeness of the overall topology, hence limited scale-free networks. Thus, it is expected that the efficiency of the flooding search reduces as the size of the hard cutoff does. We investigate the construction of scale-free topologies with hard cutoffs (i.e., there are not any major hubs) and the effect of these hard cutoffs on the search efficiency. Interestingly, we observe that the efficiency of normalized flooding and random walk search algorithms increases as the hard cutoff decreases.
A Framework for Structured Peer-to-Peer Overlay Networks
Lecture Notes in Computer Science, 2005
Structured peer-to-peer overlay networks have recently emerged as good candidate infrastructure for building novel large-scale and robust Internet applications in which participating peers share computing resources as equals. In the past three year, various structured peer-to-peer overlay networks have been proposed, and probably more are to come. We present a framework for understanding, analyzing and designing structured peer-to-peer overlay networks. The main objective of the paper is to provide practical guidelines for the design of structured overlay networks by identifying a fundamental element in the construction of overlay networks: the embedding of k−ary trees. Then, a number of effective techniques for maintaining these overlay networks are discussed. The proposed framework has been effective in the development of the DKS system, whose preliminary design appears in .
Thicket: A Protocol for Building and Maintaining Multiple Trees in a P2P Overlay
One way to efficiently disseminate information in a P2P overlay is to rely on a spanning tree. However, in a tree, interior nodes support a much higher load than leaf nodes. Also, the failure of a single node can break the tree, impairing the reliability of the dissemination protocol. These problems can be addressed by using multiple trees, such that each node is interior in just a few trees and a leaf node in the remaining; the multiple trees approach allows to achieve load distribution and also to send redundant information for fault-tolerance. This paper proposes Thicket, a decentralized algorithm to efficiently build and maintain such multiple trees over a single unstructured overlay network. The algorithm has been implemented and is extensively evaluated using simulation in a P2P overlay with 10.000 nodes.
Greedy routing in peer-to-peer systems
2006
We consider the problem of designing an overlay network and routing mechanism that per-mits finding resources efficiently in a peer-to-peer system. We argue that many existing ap-proaches to this problem can be modeled as the construction of a random graph embedded in a ...
2010 IEEE 16th International Conference on Parallel and Distributed Systems, 2010
We present 3nuts, a self-stabilizing peer-to-peer (p2p) network supporting range queries and adapting the overlay structure to the underlying physical network. 3nuts combines concepts of structured and unstructured p2p networks to overcome their individual shortcomings while keeping their strengths. This is achieved by combining self maintaining random networks for robustness, a search tree to allow range queries, and DHTs for load balancing. Simple handshake operations with provable guarantees are used for maintenance and self-stabilization. Efficiency of load balancing, fast data access, and robustness are proven by rigorous analysis.
Efficient Search in Structured Peer-to-Peer Systems: Binary v.s. K-Ary Unbalanced Tree Structures
Lecture Notes in Computer Science, 2004
We investigate the search cost in terms of number of messages generated for routing queries in tree-based P2P structured systems including binary and k-ary tree structures with different arities and different degrees of imbalance in the tree shape. This work is motivated by the fact that k-ary balanced tree access structures can greatly reduce the number of hops for searching compared to the binary trees. We study to what extent the same fact is true when the tree-like structures for access in P2P environments are unbalanced. Another important issue related to P2P environments is how to build these structures in a self-organizing way. We propose a mechanism for constructing k-ary tree based decentralized access structure in a self-organizing way and based on local interactions only. The ability to search efficiently also on unbalanced k-ary trees opens interesting opportunities for load balancing as has been shown in earlier work on P-Grid, our approach to structured P2P systems.
Parallelizing Peer-to-Peer Overlays with Multi-Destination Routing
2007
are the basic indexing mechanism for decentralized peer-to-peer systems. How to obtain best performance in a largescale wide area context for DHT operations is an important question. Here we introduce parallelization of overlay and DHT operations using native multidestination multicasting, resulting in significant message traffic reduction for both overlay maintenance and lookup operations. We show through simulation savings of up to 30% message reduction for the 1-hop EpiChord peer-to-peer overlay.
Topologies in Unstructured Peer To Peer Networks
IJMER
Abstract: The Peer-to-Peer (P2P) architectures that are most prevalent in today's Internet are decentralized and unstructured. As the peers participating in unstructured networks interconnect randomly, they rely on flooding query messages to discover objects of interest and thus introduce remarkable network traffic. Empirical measurement studies indicate that the peers in P2P networks have similar preferences, and have recently proposed unstructured P2P networks that organize participating peers by exploiting their similarity. The resultant networks may not perform searches efficientlyand effectively because existing overlay topology construction algorithms often create unstructured P2P networks without performance guarantees. Thus, we propose a novel overlay formation algorithm for unstructured P2P networks. Based on the file sharing pattern exhibiting the power-law property, our proposal is unique in that it poses accurate performance guarantees. Based on the simulation results, our proposal clearly outperforms the competing algorithms in terms of 1) the hop count of routing a query message, 2) the successful ratio of resolving a query, 3) the number of messages required for resolving a query, and 4) the message overhead for maintaining and formatting the overlay.