This document is a product of the Delay Tolerant Networking Research Group and has been reviewed by that group. No objections to its publication as an RFC were raised. This document defines PRoPHET, a Probabilistic Routing Protocol using History of Encounters and Transitivity. PRoPHET is a variant of the epidemic routing protocol for intermittently connected networks that operates by pruning the epidemic distribution tree to minimize resource usage while still attempting to achieve the best-case routing capabilities of epidemic routing. It is intended for use in sparse mesh networks where there is no guarantee that a fully connected path between the source and destination exists at any time, rendering traditional routing protocols unable to deliver messages between hosts. These networks are examples of networks where there is a disparity between the latency requirements of applications and the capabilities of the underlying network (networks often referred to as delay and disruption tolerant). The document presents an architectural overview followed by the protocol specification. Status of This Memo This document is not an Internet Standards Track specification; it is published for examination, experimental implementation, and evaluation.

Research within Delay-and Disruption Tolerant Networks (DTN) has evolved into a mature research area. PRoPHET is a routing protocol for DTNs that was developed when DTN research was in its infancy and which has been studied by many. In this paper we investigate how the protocol can evolve to meet new challenges that has been identified through research and practical experience.We propose some minor modifications to the routing metric calculations done in PRoPHET which has potential to alleviate some issues and improve the performance of the protocol. Using these modifications, we define an updated version of the protocol called PRoPHETv2. We run simulations to verify the operation of the protocol and compare its performance against the original version of the protocol as well as some other routing protocols. The evaluations are done using both traces from an existing DTN deployment and a synthetic mobility model. Since the basic mechanisms of the protocol remain the same, migrating existing implementations to the new version of PRoPHET is possible with limited effort.

Over the past decade, a lot of research has been done to develop efficient routing protocols for Delay-and Disruption Tolerant Networks (DTNs). In the course of this work, many comparative evaluation studies have been done to determine which of two proposed protocols is the better one (for a given situation). The majority of these evaluations are based on results gained from simulated network environments. In order to conduct a relevant evaluation of routing schemes, numerous conditions, policies and data need to be specified and fed into the simulation environment. The aim of our work in this paper is to discuss current DTN evaluation practices through a thorough and critical literature study. Based on the surveyed material, we show some weaknesses and lack of argumentation used in the evaluations. Through this, we hope to aid in bridging the gap between simulated and real-world DTN environments. In addition, and as a call for further research, we propose a model for evaluation of DTN routing schemes that outlines the most crucial inputs that needs to be considered in the evaluation process. This model is then projected onto evaluation practices used for evaluations of DTN routing protocols in a set of sixteen papers roughly covering a decade of DTN research.

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This study investigates how environments into which new technologies are introduced interact and interfere with the deployment process, the deployed technologies as well as the research conducted. The material that is used in this study draws from the N4C project development and deployment of Delay Tolerant Network (DTN) technology in the remote Arctic villages of Ritsem and Staloluokta. As the development of DTN technology prior to the deployment was conducted primarily in the laboratories, its usability and functionality still needed to be proven on the field of deployment. Here, Actor Network Theory (ANT) was employed to reveal how climate, flora, fauna and other elements present in the field of deployment interacted and interfered with, but more importantly, drove the technological development and the continued research work.