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MANET Supernodes

MANET Supernodes. March 16, 2005 Barry Demchak Zhong-Yi Jin William Chang. Problem. How to create a file system on a MANET that is reliable, energy efficient, and has low latency?. MANET. Mobile Ad-hoc NETwork Characteristics Wireless Energy constrained Transient nodes Nodes are hosts.

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MANET Supernodes

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  1. MANET Supernodes March 16, 2005 Barry Demchak Zhong-Yi Jin William Chang

  2. Problem • How to create a file system on a MANET that is reliable, energy efficient, and has low latency?

  3. MANET • Mobile Ad-hoc NETwork • Characteristics • Wireless • Energy constrained • Transient nodes • Nodes are hosts and routers

  4. Related Works • Ekta • DHT substrate on MANET • Not a file system • Not energy efficient • Pangaea • Meta-data/data replication • Not on MANET

  5. SN1 D SN3 SN5 M M D M SN2 SN3 M D M SN4 M – Meta Data D – Data Hash(D) = SN3 Our Approach • Group nodes into Supernodes

  6. Components • Supernode – group of nodes sharing a common set of meta-data • Meta-data – information about the locations and the name of data • Data – shared file residing at one or more nodes • Hash() – consistent hashing value of data name

  7. Goals • Reliability • Low latency • Energy efficiency Replication of meta-data and data Node group coverage Node group coverage Meta-data propagation optimization

  8. Picture Viewer Results Grabber Application File Save/ Retrieve File Delete File List File System Meta-Data Save/Retrieve File System Replication Join / Leave Split / Merge Supernode Level Routing Meta-Data Replication Packet Delivery Route Discovery Node Level Routing Architecture

  9. Picture Viewer Results Grabber Application File Save/ Retrieve File Delete File List File System Meta-Data Save/Retrieve File System Replication Join / Leave Split / Merge Supernode Level Routing Meta-Data Replication Packet Delivery Route Discovery Node Level Routing Project Scope

  10. Join

  11. File Retrieve M M M M D D

  12. M M M File Retrieve (Retro) M M M M M D D M

  13. M M M M File Save D

  14. Meta-data Propagation • Forward to every neighbor • Poison list optimization M M M M M M M M M M

  15. Experiment • Simulated on P2PSim • Measure reliability • Measure energy / latency • Measure poison list optimization

  16. P2PSim

  17. Reliability Sweet spot at 3-5 nodes per supernode

  18. Reliability (cont.) With few nodes per supernode, odd are that supernode will die before data node

  19. Reliability (cont.) 3 nodes per supernode seem sufficient for protection of up to 5 file copies

  20. Energy Larger supernodes have edges closest to any particular node on network

  21. Energy (cont.) Latency and energy drop because of spatial locality due to more file copies

  22. Scenario A M

  23. Scenario B M M M M

  24. Latency Assuming 1400 bytes/packet, large files simply involve more packets

  25. Poison List Poison list is important energy optimization – definitely worth space in packet

  26. Poison List (cont.) Poison list shorter than number of nodes in supernode causes energies and latencies non-linear with respect to supernode size

  27. Poison List (cont.) Supernode update energy is linear with respect to supernode size

  28. Routing among Groups • Apply DHT (Chord) to MANET • Characteristics of wireless network • Locality: Shared media, limited range • Mobility: Fast node join/leave • Limited capability: Distribute Load

  29. Child Node Super node Super node Child Node Join Chord Ring Join the group Request super node’s chord info Connect Group to Ring

  30. Reduce total Number of Joins

  31. Performance Super node Child Node

  32. Conclusion • Reliability achieved through replication of meta-data and data • Low latency & energy efficiency achieved through node grouping • Scalability traded for energy efficiency

  33. Future Work • Routing layer • Merge/Split supernodes • File delete/modify • File listing • More realistic experiments • Mix node join and crash • Realistic routing latency • Realistic energy cost • Packet loss

  34. Q & A

  35. Thank You

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