Geometries considered Geometry Algorithm Ring Chord Symphony Hypercube
Geometries considered Geometry Algorithm Ring Chord, Symphony Hypercube CAN Tree PRR Hybrid = Tree + Ring Tapestry, Pastry XOR d(id 1, id 2) = id 1 XOR id 2 Kademlia 4
Geometry => Flexibility => Performance l Geometry captures flexibility in selecting algorithms l Flexibility is important for routing performance ¡ Flexibility in selecting routes leads to shorter, reliable paths ¡ Flexibility in selecting neighbors leads to shorter paths 5
Metrics for flexibility l FNS: Flexibility in Neighbor Selection = number of node choices for a neighbor l FRS: Flexibility in Route Selection = avg. number of next-hop choices for all destinations l Constraints for neighbors and routes ¡ ¡ select neighbors to have paths of O(log. N) select routes so that each hop is closer to destination 6
Summary of flexibility analysis Flexibility Ordering of Geometries Neighbors Hypercube << Tree, XOR, Ring, Hybrid (FNS) Routes (FRS) (1) (2 i-1) Tree << XOR, Hybrid < Hypercube < Ring (1) (log. N/2) (log. N) How relevant is flexibility for DHT routing performance? 7
Static Resilience Two aspects of robust routing Dynamic Recovery : how quickly routing state is recovered after failures l Static Resilience : how well the network routes before recovery finishes l ¡ captures how quickly recovery algorithms need to work ¡ depends on FRS Evaluation: Fail a fraction of nodes, without recovering any state l Metric: % Paths Failed l 8
Does flexibility affect Static Resilience? Tree << XOR ≈ Hybrid < Hypercube < Ring 9
Geometry’s impact on Proximity l Both ¡ FNS and FRS can reduce latency Tree has FNS, Hypercube has FRS, Ring & XOR have both l Metric: Overlay Path Latency 10
Which is more useful: FNS or FRS? Plain << FRS << FNS ≈ FNS+FRS Neighbor Selection is much better than Route Selection 11
小结 l 拓扑结构影响性能,其中FRS对resilence 显著,而FNS对latency显著。设计需要 tradeoff l 参考论文: l [Gummadi et al. 03] K. P. Gummadi, R. Gummadi, S. D. Gribble, S. Ratnasamy, S. Shenker and I. Stoica. The Impact of DHT Routing Geometry on Resilience and Proximity. In SIGCOMM 2003, pp. 381 -394. 12
Open. DHT体系结构 18
Examples: Here is an example usage scenario: l $. /put. py colors red Success l $. /get. py l ¡ colors red $. /put. py --secret donttell colors blue Success l $. /get. py colors l ¡ red blue $. /rm. py colors blue donttell Success l $. /get. py colors l ¡ red 19
l 结构化P 2 P网络中的模糊查询方法 ¡ 关键码搜索 ¡ 语义搜索 VSM vector space mode l LSI latent semantic index l Refer to [Tang et. al. 2003]&[Zhu et. al. , 2003] l 30
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学期论文IDEA之三 l Searching Similarity Documents ¡ ¡ l Interest-Cluster ¡ l PAIS: A Proximity-Aware Interest-Clustered P 2 P File Sharing System, CCGrid 2009, Haiying Shen Routing Indices ¡ l unstructured overlay Structured overlay Adaptive Resource Indexing Technique for Unstructured Peer-to. Peer Networks, CCGrid 2009, Sumeth Lerthirunwong, Naoya Maruyama, and Satoshi Matsuoka Range Query ¡ Range Query Using Learning-Aware RPS in DHT-Based Peer-to -Peer Networks, CCGrid 2009, Ze Deng, Dan Feng, Ke Zhou, Zhan Shi, and Chao Luo 57
下次课前阅读: [Cohen and Shenker. 02] Edith Cohen and Scott Shenker. Replication Strategies in Unstructured Peerto-Peer Networks. In SIGCOMM 2002, pp. 84 -95. l Rao et al. 03] Ananth Rao, Karthik Lakshminarayanan, Sonesh Surana, Richard Karp, Ion Stoica. Load Balancing in Structured P 2 P Systems. In IPTPS 2003, pp. 68 -79. l Balancing Locality and Randomness in DHTs Shuheng Zhou, Gregory R. Ganger, Peter Steenkiste. Carnegie Mellon University Technical Report CMU-CS 03 -203, November 2003. l 59
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