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Rapid Content Distribution Using An Ordered Seeding Torrent

Rapid Content Distribution Using An Ordered Seeding Torrent. Raja Naresh Dr. Javed Khan Media Communications Networking Research Lab Kent State University. Outline. Problem Description and Background Terms and Assumptions Overlay Network The Technique Seeding Distribution Process

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Rapid Content Distribution Using An Ordered Seeding Torrent

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  1. Rapid Content Distribution Using An Ordered Seeding Torrent Raja Naresh Dr. Javed Khan Media Communications Networking Research Lab Kent State University

  2. Outline • Problem Description and Background • Terms and Assumptions • Overlay Network • The Technique • Seeding • Distribution • Process • Time Complexity Analysis • Big Picture • Experimental Evaluation • Bound Achieved

  3. Problem Description and Background • Content Distribution Networks (CDNs) is a system of computers containing copies of data placed at various nodes of a network. • Companies sign-up with CDN providers with their services. • Synchronization of content b/w the CDN nodes. • Given N nodes in a network we want to efficiently (as fast as possible) distribute a file to all the nodes.

  4. Terms and Assumptions • Two kinds of nodes. • The Seed which has the file/content to be distributed. Only one Seed. • Non-Seed/Sink/Peers to which the content has to be distributed. They are represented with a unique binary ID eg. :- nodeID = 101001 • Sink nodes are connected forming an overlay network such that their hamming distance = 1. Represents a hypercube structure. • The Seed is connected to all the Sink nodes. • Takes 1 unit of time to transfer file b/w any two nodes.

  5. Overlay Network 000 001 00 01 010 011 100 101 10 11 110 111 2-D hypercube 3-D hypercube

  6. The Technique • Fragmentation and Broadcasting. • Fragments also have unique binary ID. Fragment 1 Fragment 2 … Fragment N [00...00] [00...01] … [11...11] • Each fragment is of size 1/N hence fragment transfer b/w any two nodes takes 1/N units of time. • We call this one timestamp.

  7. Seeding • The Seed is responsible for fragmenting the file into N fragments. • Sends fragmentID to nodeID. Formulates an array consisting of the destination nodeID. • Sends the fragmentID to the Sink with same nodeID. • The array index represents the senquence in which the fragmentID is transferred to nodeID. 000 111 011 100 001 110 010 101 3-D illustration of the Seeding algorithm (8 nodes)

  8. Seeding 000 000 001 000 011 001 010 011 000 111 100 001 110 010 101

  9. [000] [000] [000] [000] [000] [000] [000] Distribution • General Idea is the same as broadcasting in parallel network such as hypercube. • Consider a fragmentID [000] being distributed. Analysis of node 001 [000] 001-->{011, 101} 000 001 010 011 100 101 110 111 3-D hypercube

  10. [000] [000] [111] Process 000 001 000 001 010 011 010 011 100 100 101 101 110 111 110 111 Timestamp 1 Timestamp 2

  11. [000] [000] [011] [000] [000] [011] [100] [111] [111] [111] Process 000 001 000 001 010 011 010 011 100 100 101 101 110 111 110 111 Timestamp 3 Timestamp 4

  12. [001] [001] [011] [011] [111] [011] [111] [100] [100] [111] [000] [111] [011] [110] Process 000 000 001 001 000 001 010 010 011 011 010 011 100 100 100 101 101 101 110 110 111 111 110 111 Timestamp 5 Timestamp 6

  13. Time Complexity Analysis • The minimum number of timestamps required is N since the seed forwards atleast N fragments. • Discard half of the fragments. If the last bit is different then the node doesn't need to forward the fragment to any other node. It's the last node to receive the frag- ment 000 001 • Hence we only consider d-1 bits among d bits. 010 011 100 101 => N+... 110 111

  14. Time Complexity Analysis • Consider last node with nodeID = 1d-11d-2...1110 • When fragmentID = nodeID, distributes fragment in d timestamps. • When (d-2)th bit is different, distributes fragment in 1X2d-2 timestamps 000 001 • When (d-3)rd bit is different, distributes fragment in 2X2d-3 Which is 2X(2d-2/2) 010 011 => N+d+1X2d-2+2X(2d-2/2)... 100 101 110 111

  15. Time Complexity Analysis => N + d + 1X2d-2 + 2X(2d-2/2) … + (d-1)X(2d-2/2d-2) => N + N – 1 => 2N – 1 # of timestamps in worst case => 2 – (1/N) Actual time taken to distribute Big Picture Sequential – N Broadcasting – (logN) Fragmentation and Broadcasting - O(1)

  16. Experimental Evaluation Experimental Time Complexity = 1 + O((log2N)/N)

  17. Further Extensions • Optimality of the Seeding algorithm • Include Header cost and find the optimal N. Thank you

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