Johannes Morgenroth

IBR-DTN: A lightweight, modular and highly portable Bundle Protocol implementation

In this paper we present IBR-DTN, a lightweight, modular and portable Bundle Protocol implementation and DTN daemon. IBR-DTN is especially suited for embedded platforms, which allows to leverage the benefits of a fully compliant Bundle Protocol daemon in cost sensitive distributed sensing applications. We line out IBR-DTNs extensible software architecture and introduce the modules included in the standard IBR-DTN distribution. To give an impression of the performance that can be expected when using IBR-DTN, we perform a series of benchmarks and compare the outcome with DTN2 performance, the reference implementation of the Bundle Protocol.

Performance comparison of DTN bundle protocol implementations

In recent years, Delay Tolerant Networking (DTN) has received a lot of interest from the networking community. Today the Bundle Protocol (RFC 5050) is the standard communication protocol in DTNs and several implementations for various platforms are available. As of now, no quantitative analysis of the different implementations performance or a structured evaluation of interoperability has been undertaken. We performed interoperability checks and an extensive quantitative performance analysis of three Bundle Protocol implementations for Linux systems. In this paper we summarize our main findings. While the overall results show, that all implementations provide some baseline compatibility with each other, the stability and achieved performance under stress situations varies widely between implementations.

A bundle protocol implementation for android devices

In this demo we present IBR-DTN for Android: IBR-DTN is a fully featured RFC5050 compliant Bundle Protocol implementation that can run on un-rooted Android devices starting from Android Version 2.3 (Gingerbread). IBR-DTN for Android supports all features of the IBR-DTN version for PCs and embedded systems. It is available in the Google Play Store for free. In addition to the protocol stack we provide two simple real world applications: a text messaging system and a push-to-talk application. They can serve as an example how to build DTN applications for mobile phones as both applications as well as the protocol implementation itself are open sourced.

HYDRA: virtualized distributed testbed for DTN simulations

We present and evaluate HYDRA, a virtualized testbed for realistic large-scale network simulations. While classic simulation tools only provide approximations of the protocol stack, HYDRA virtualizes nodes running a complete Linux system. Mobility models and connection management integrated into HYDRA allow for the simulation of various wireless networking scenarios. Our distributed virtualization approach achieves excellent scalability and the automated node setup makes it easy to deploy large setups with hundreds of nodes. Hardware-in-the-loop simulations are possible, using HYDRA to augment a testbed of real devices. The ability to boot a HYDRA node completely from an USB flash drive enables the user to convert temporarily unused computer resources into a testbed without the need for any complex setup.

Free-riding the BitTorrent DHT to improve DTN connectivity

Until now there exists no standardized or widely-used name resolution mechanism for Bundle Protocol based DTNs. In local IP based networks the IP Neighbor Discovery (IPND) protocol provides link-local discovery of DTN neighbors, however in the Internet there is no mechanism that maps Bundle Protocol addresses (EIDs) to Convergence Layer addresses. This seriously hampers connectivity in the DTNBone. In this paper we argue, that a DHT-based naming mechanism is a good fit for DTN networks. We show the advantages of using the existing DHT infrastructure from the BitTorrent file sharing network as a basis instead of rolling out a custom solution. We will present experiences and performance measures with a lightweight implementation of the proposed system that we began to distribute as integrated component of the IBR-DTN Bundle Protocol implementation.

Live-streaming in delay tolerant networks

Streaming of audiovisual media contents such as video or music using mobile devices and wireless networks leads to new challenges because these network connections are typically not very reliable. In this demo, we show streaming of live video using a Delay Tolerant Network (DTN) approach. This allows the integration of multiple connections which leads to a higher availability and enables a video transmission without loss in the data stream.

Delay-tolerant networking in restricted networks

For security reasons, many companies usually allow only strictly regulated communication, specific system configurations and predetermined software components. Therefore, often only communication over the HTTP protocol is possible, which operates by using a request-response approach. In this paper we present the design and evaluation of a convergence layer for our DTN implementation IBR-DTN using HTTP as underlying protocol. On the remote side we use a web server and a database for the connection management. Through the usage of long-polling we realize a bidirectional communication. In the evaluation, we show the results of bandwidth and latency measurements.

Improving the safety of pedestrians by using a cooperative system

The number of traffic accidents with injury to persons is still too high. Hence, it is an important question, how the number of accidents with pedestrians can be reduced. We propose to integrate existing technologies and mobile devices into a cooperative system which is able to detect critical situations and execute preventive counteractive measures such as warn traffic participants. The paper starts with an analysis of the different types of accidents in a detailed accident study using the GIDAS database and reports of local accidents with pedestrians. With regard to the different types of accidents it is important to consider the reasons for each situation. The obtained knowledge is used to build general scenarios to determine on effective means to prevent such accidents. Finally, three different system architectures with varying level of capabilities and complexity are designed.

Efficient false positive free set synchronization using an extended bloom filter approach

Synchronization between two sets is an important requirement for many distributed applications. A basic prerequisite is to find out which elements of set A are not in set B and vice versa. A very space efficient data structure for such membership queries that has been used a lot in networking applications is the Bloom filter. Unfortunately, the Bloom filter owes its high efficiency to the fact that there is a chance of false positives when querying the filter. This precludes the adoption of Bloom filters in applications that cannot tolerate such errors. In this paper we present an approach that augments Bloom filters with a trie-based mechanism that deterministically and efficiently finds the false positives after using the Bloom filter to synchronize two sets. We show that the added communication overhead for our approach is negligible compared to the overhead of a plain Bloom filter.

Performance issues and design choices in delay-tolerant network (DTN) algorithms and protocols

This chapter discusses performance-related aspects of delay-tolerant network (DTN) systems by taking a close look at the essential algorithms and mechanisms required to build any DTN implementation. First, metrics that are relevant for the performance of a DTN system are identified. The impact of IO overhead and performance on achievable data rates and transmission frequency is analyzed and the tradeoff between energy efficiency and discovery latency is discussed. Real-world data from implemented systems is presented and, based on the discussed issues and experiences with several DTN systems, suggestions for implementers and system designers will be given.