Mobile ad-hoc networks (MANETs) assume that mobile nodes volunteer collaborates in order to work appropriately. This Cooperation is a cost-intensive activity and some nodes can refuse to cooperate, leading to selfish node behaviour. Thus, the complete network performance could be seriously affected. The use of watchdogs is a well-known mechanism to detect selfish nodes. However, the detection process performed by watchdogs can fail, generating false positives and false negatives that can induce to wrong operations. Moreover, relying on local watchdogs alone can lead to poor performance when detecting selfish nodes, in term of precision and speed. This is especially important on networks with sporadic contacts, such as Delay Tolerant Networks (DTNs), where sometimes watchdog’s lack of enough time or information to detect the selfish nodes. Thus, Collaborative Contact-based Watchdog (CoCoWa) is proposed as a collaborative approach based on the diffusion of local selfish nodes awareness when a contact occurs, so that information about selfish nodes is quickly propagated. As shown in the paper, this collaborative approach will make the selfish node as trusted node by using AODV protocol and provide better security.

CoCoWa Architecture, Watchdog, Delay Tolerant Networks, Trust model, Security,Routing Protocol, AODV

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