Time-reference distribution in delay tolerant networks

A delay tolerant network (DTN) deals with the issue of frequently interrupted connections and relaxes the need for a continuous end-to-end relation between nodes. The Bundle Protocol is the typical way to set-up a DTN, but requires a common time in the whole network. Further, globally synchronized timestamps are required by many mechanisms like cryptography protocols or global event ordering. Since standard time synchronization approaches from classical networking do not work in DTNs, we introduce a novel algorithm to distribute a time reference in such networks. Our approach rates the quality of the local time with respect to the accuracy of the local clock. We show that this simple and self-aligning algorithm can provide an adequate accuracy depending on the inter-contact times between the nodes.