A DTN Gateway-based Architecture for Web Access in Space Internet

Abstract

Delay tolerant networking (DTN) offers a novel way to successfully transfer information over severely delayed, disrupted or periodically disconnected networks. Such delays or disruption would either cause the transmission control protocol (TCP) to fail or perform extremely poorly. A Delay/Disruption-Tolerant Network (DTN) has received more attention as an expected solution in situations where it is difficult to provide a stable and continuous Internet connection. The research presented here shows the design of a client-server model for space Internet in order to have access to the web documents hosted by an interplanetary node. One of the DTN implementations named Interplanetary Overlay Network (ION) is introduced to provide the main functions to allow networked communications in deep space. In this paper, we propose an architecture for web document access in space Internet over DTN. Our web architecture is based on the DTN Gateway between terrestrial and space Internet that acts as a web proxy or bundle forwarder according to the type of web documents; it works as a web proxy for static web documents, while it works as bundle forwarder between DTN client and DTN server for other web documents. The HyperText Transfer Protocol (HTTP) requests and responses are formatted onto bundles by using bpsendfile and bprecvfile, and the DTN Gateway forwards them as a contact basis in space Internet. We have reported the evaluation results from our implementation by measuring the bit error rate and delay according to the size of static web documents. The test environment was used to perform experiments on the DTN implementation and Interplanetary Overlay Network. These were run over both TCP and UDP and as expected show resilience and better performance as delays are increased. However, ION running the Licklider Transmission Protocol showed the ability to transfer successfully a web document file by using the Bundle Protocol between nodes. A comprehensive literature review provides an up to date insight into DTN's short history and the state of current research.