Routing in a delay tolerant network

TLDR

Delay‑tolerant networking routing requires moving messages across a time‑varying connectivity graph with finite buffers and no simultaneous end‑to‑end path, limiting the applicability of traditional routing that assumes persistent paths. The authors propose a framework for evaluating routing algorithms in such environments. They develop several algorithms and use simulations to compare their performance relative to the amount of network topology knowledge required. Algorithms with minimal knowledge perform poorly, whereas limited additional knowledge—far less than full global knowledge—enables efficient routing, marking the first investigation of routing issues in DTNs.

Abstract

We formulate the delay-tolerant networking routing problem, where messages are to be moved end-to-end across a connectivity graph that is time-varying but whose dynamics may be known in advance. The problem has the added constraints of finite buffers at each node and the general property that no contemporaneous end-to-end path may ever exist. This situation limits the applicability of traditional routing approaches that tend to treat outages as failures and seek to find an existing end-to-end path. We propose a framework for evaluating routing algorithms in such environments. We then develop several algorithms and use simulations to compare their performance with respect to the amount of knowledge they require about network topology. We find that, as expected, the algorithms using the least knowledge tend to perform poorly. We also find that with limited additional knowledge, far less than complete global knowledge, efficient algorithms can be constructed for routing in such environments. To the best of our knowledge this is the first such investigation of routing issues in DTNs.