A Membership Management Protocol for Mobile P2P

NetworksMohamed Karim SBAI, Emna SALHI, Chadi BARAKAT

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

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

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.

A membership management protocol for P2P services run over MANET ?

Client / Server Flooding-based method Multicast-based method P2P

Adaptive and optimal P2P method ?

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:

1. Joining the membership tree2. Leaving the membership tree3. Adapting the membership tree to mobility of nodes4. Network split awareness

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.

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

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.

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.

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.

Packet format

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

Performance evaluation

Client/server method

Performance evaluation

Performance evaluation

Performance evaluation

Performance evaluation

Performance evaluation

Performance evaluation

Thank You

mksbai@sophia.inria.fr