Assessing the vulnerability of DTN data relaying schemes to node selfishness

Delay tolerant networks rely on the mobility of their nodes and sequences of their contacts to transfer data. Proposed data forwarding mechanisms represent different trade offs between data transfer speed and network resource consumption, most of them assuming perfect cooperation among network nodes. Nevertheless, nodes may exhibit selfish behavior, in particular when they are constrained with respect to energy, computational power, and/or storage space. In this paper, we analytically assess the performance of two popular data relaying alternatives, the unrestricted and two-hop relay schemes, when nodes behave selfishly while forwarding data. Our results suggest that the performance advantage of unrestricted relaying over two-hop relaying decreases both with the number of selfish nodes and the intensity of their selfishness, irrespective of whether nodes defer from relaying deterministically or probabilistically. We use our model to quantify the vulnerability of the two relaying schemes to node selfishness but also drive remediation actions against it.