Seamless deployment of IP applications over delay tolerant network (DTN)

Abstract

Delay tolerant network (DTN) is a network architecture that is capable of transporting data in a challenged environment or one with intermittent connectivity. Its store-and-forward functionality allows easy deployment of ad-hoc or distributed network infrastructure during disaster or disrupted situations, and maintains data delivery assurance over its persistent storage among DTN nodes. Nowadays, DTN deployment using popular wireless technology (such as Bluetooth, Wi-Fi and so on) could only cover small regions of ad-hoc network owing to the short transmission range of the technology. Although the opportunistic contact of DTN is able to propagate among small ad-hoc networks to cover a wider region, vast areas such as the sea and forests still challenge DTN and hinder further propagation. The old long-range transmission (like amateur radio using UHF radio band) would extend current DTN deployment to a wider space using DTN serial convergence layer. The original serial convergence layer of DTN reference implementation was enhanced with significant improvement on multiple access control and on-the-fly neighbor discovery. A complete replacement of existing IP networks with DTN does not bring tremendous advantages owing to global network equipment costs and DTN protocol overhead. Instead, the use of DTN as a network overlay or complement is more feasible and appropriate. Proxy agent for DTN is proposed. Initially, a redirection of IP traffic over user-aware DTN proxy was developed. The implementation of user-aware DTN proxy was tested on web browsing, which contributes significantly to the network traffic on the Internet. The user-aware DTN proxy restricts DTN overlay in terms of configurable IP applications such as web browser and email client. DTN proxy was further developed into a seamless DTN proxy which intercepts traffic from the well-known application port and transports the traffic over DTN. The seamless DTN proxy is totally transparent to user and requires no modification or configuration on the application layer. The underlying proxy handles the lower layer issue (such as TCP end-to-end connectivity and timeout). Most IP applications are transported over TCP and/or UDP. To mitigate the development of different DTN proxies to support different IP applications, DTN proxy is further evolved into generic seamless type, DTN GSProxy. DTN GSProxy has TCP and UDP engines (handlers) to support one or both transport layers simultaneously. For instance, HTTP surfing (TCP) needs to resolve the IP address from the given URL name prior to the DNS protocol (UDP).