  To achieve end-to-end delivery in intermittently connected networks, epidemic
routing is proposed for data delivery at the price of excessive buffer
occupancy due to its store-and-forward nature. The ultimate goal of epidemic
routing protocol design is to reduce system resource usage (e.g., buffer
occupancy) while simultaneously providing data delivery with statistical
guarantee. Therefore the tradeoffs between buffer occupancy and data delivery
reliability are of utmost importance. In this paper we investigate the
tradeoffs for two representative schemes: the global timeout scheme and the
antipacket dissemination scheme that are proposed for lossy and lossless data
delivery, respectively. For lossy data delivery, we show that with the
suggested global timeout value, the per-node buffer occupancy only depends on
the maximum tolerable packet loss rate and pairwise meeting rate. For lossless
data delivery, we show that the buffer occupancy can be significantly reduced
via fully antipacket dissemination. The developed tools therefore offer new
insights for epidemic routing protocol designs and performance evaluations.
