Delay-/Disruption-Tolerant Networking State of the Art and Future Challenges

Networking for challenged environments, or Delayand Disruption-Tolerant Networking as it is now most commonly referred to, has attracted great attention in the past few years by the networking research community. Connectivity disruptions, limited network capacity, energy and storage constraints of the participating, mobile devices and the arbitrary movement of nodes are only a few of the challenges that the protocol stack has to deal with. Clearly, current Internet protocols (i.e., the TCP/IP protocol stack) suffer and can fail under such conditions. In this paper, we initially give the DTN Problem Statement ; we contend that not all applications have the same requirements from the system and hence, equal (blind) treatment of all data packets will result in reduced network efficiency. Based on that we propose a Design Position for DTN protocols, which states that protocol design has to be done proactively, on the basis of the application’s requirements. We then survey the most recent contributions on the whole spectrum of Delayand Disruption-Tolerant Networking, from the architectural and the application point of view down to the transportand the network-layer of the emerging DTN protocol stack. We find that although not explicitly mentioned ∗Corresponding author Email addresses: [email protected] (Ioannis Psaras), [email protected] (Lloyd Wood), [email protected] (Rahim Tafazolli) Preprint submitted to Elsevier November 5, 2009 in most cases, research trends follow our Design Position. To the best of our knowledge this is the first study that discusses and evaluates research contributions from such a broad perspective. Finally, we highlight research challenges and open issues that require further investigation.