A Membership Management Protocol for Mobile P2P Networks

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A Membership Management Protocol for Mobile P2P
Networks

• Mohamed Karim SBAI, Emna SALHI, Chadi BARAKAT

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Mobile Ad hoc Networks

• Spontaneous multi-hop wireless networks
• end-to-end communication ?? ad hoc routing
  protocols ? ?
• Without any established infrastructure ? ?
• Nodes play symmetric roles ?? No dedicated
  nodes. ? ?
• Using wireless channel ? ?
• Limited and shared resources ?
• Mobility ?? Network splits ? ?

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P2P Networks

• Peer-to-peer services (as known in the Internet)
• Without dedicated devices (servers) ? ?
• Peers play symmetric roles ?? Both clients and
  servers. ? ?
• Can use fixed servers to track the members of
  the overlay ? ?
• The mechanism are not adapted to mobile
  constrained environments ?

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Membership Management Protocol for mobile P2P
networks

• Objective
• Maintaining an up-to-date list of the peers
  interested in the P2P service.
• Challenges- Minimum cost on the underlying
  network.
• - Ensuring the continuity of the service.-
  Having a good level of the freshness of
  information.

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A membership management protocol for P2P services
run over MANET ?

• Client / Server ?
• Flooding-based method ?
• Multicast-based method ?
• P2P ? ?
• Adaptive and optimal P2P method ? ?

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Membership Management Protocol

• Our solution
• A fully distributed protocol for constructing
  and maintaining minimum spanning trees of
  interested peers.
• robust
• adaptive
• network friendly
• decentralized
• Algorithms
• Joining the membership tree
• Leaving the membership tree
• Adapting the membership tree to mobility of nodes
• Network split awareness

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Joining the membership tree

• Looking for the nearest peer ? a
  controlled-scope flooding method
• Connecting to the nearest peer and getting the
  current tree from it
• Dissemination of the new arrival information on
  the tree
• Changing some connections of the tree
  considering the cut property of a minimum
  spanning tree.

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Adapting the tree to mobility of nodes

• Two peers that are neighbors in the tree can get
  closer ? the tree is still optimal.
• Two peers that are not neighbors in the spanning
  tree get farther from each other ? the cost of
  the tree does not change and no better decision
  can be made.
• Two peers that are neighbors in the spanning
  tree get farther from each other. ? The cost of
  the tree increases ? there might exist a better
  tree. CASE 1
• Two peers that are not neighbors in the spanning
  tree get closer to each other ? It might be
  another tree with smaller weight. CASE 2

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Adapting the tree to mobility of nodes

• CASE I CASE 2 If one of the peers get nearer
  to another peer in the tree. Else, no
  optimization can be made.
• CASE 2
• Using the cycle property of a minimum
  spanning tree to elect the logical link to cut.

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Leaving the membership tree

• The child of the leaving peer having the highest
  identifier connects to its parent and becomes the
  parent for the remaining children. ? A new
  spanning tree
• The optimal is reached by having the peers apply
  the normal approaching adaptation procedure.

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Network split awareness

• Tagging network nodes that are not interested in
  the same service.
• Tracks continuously the appearance of non tagged
  nodes in its neighborhood.
• A new node not tagged and not belonging to the
  same membership tree is a good candidate to be
  asked whether it belongs to the same service but
  comes from another cluster.
• Executing a join procedure in case the node is a
  peer.

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Packet format
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Performance evaluation

• Performance metrics
• Real cost number of hops message
• Cost corrected by freshness of information

• NS-2 Simulations scenario
• 50 nodes / Random way point (2ms, 30s) / OLSR
  routing protocol
• exponentiel distribution of ON and OFF times of
  peers

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Performance evaluation

• Client/server
  method

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Performance evaluation
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Performance evaluation
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Performance evaluation
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Performance evaluation
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Performance evaluation
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Performance evaluation
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Thank You

• mksbai_at_sophia.inria.fr