This paper addresses the routing problem in Delay Tolerant Networks (DTNs), where messages must be transmitted end-to-end across a time-varying connectivity graph with finite buffers at each node. The authors propose a framework for evaluating routing algorithms in such environments and develop several algorithms, comparing their performance through simulations. They find that algorithms requiring less knowledge about the network topology tend to perform poorly, and that efficient algorithms can be constructed with limited additional knowledge. The paper also includes an optimal algorithm based on linear programming for comparison. The authors motivate the DTN routing problem using a scenario involving a remote village and various connectivity options, such as a digital courier, a wired dial-up connection, and a store-and-forward LEO satellite. The paper discusses the DTN network model, routing issues, and evaluates different routing algorithms, including those with zero, partial, and complete knowledge. The performance of these algorithms is assessed using a custom simulator for DTN environments, demonstrating the effectiveness of the proposed algorithms in various scenarios.This paper addresses the routing problem in Delay Tolerant Networks (DTNs), where messages must be transmitted end-to-end across a time-varying connectivity graph with finite buffers at each node. The authors propose a framework for evaluating routing algorithms in such environments and develop several algorithms, comparing their performance through simulations. They find that algorithms requiring less knowledge about the network topology tend to perform poorly, and that efficient algorithms can be constructed with limited additional knowledge. The paper also includes an optimal algorithm based on linear programming for comparison. The authors motivate the DTN routing problem using a scenario involving a remote village and various connectivity options, such as a digital courier, a wired dial-up connection, and a store-and-forward LEO satellite. The paper discusses the DTN network model, routing issues, and evaluates different routing algorithms, including those with zero, partial, and complete knowledge. The performance of these algorithms is assessed using a custom simulator for DTN environments, demonstrating the effectiveness of the proposed algorithms in various scenarios.