On design and implementation of a scalable and reliable Sync system for delay tolerant challenged networks

Seamless data synchronization among peer entities is a problem for any challenged network scenarios where infrastructural supports for synchronization are not available or insufficient. Such a network follows a delay/disruption tolerant approach, in which connection or contact time among devices are intermittent and short-lived, agents may use devices of heterogeneous nature with different communication and processing powers, and the communication channel may have high loss rate that impacts the application layer file synchronization protocols. The bundle protocol specifications for delay tolerant networks only describe the semantics for data transmission between two distant devices, and do not specify how a peer-to-peer (P2P) file synchronization protocol can cater seamless data exchange among multiple heterogeneous communication devices. We propose in this paper a new P2P sync, called pSync, on the top of the bundle protocol which precisely takes care of prioritized file Sync with role based transfer applicable for challenged networks. Our testbed experiments conducted with information dropbox, ground and aerial data mule suggest that pSync is scalable and clearly outperforms BitTorrent Sync in delivering even 30% more priority packets in certain test cases.