Peer-to-Peer-Technologie in Teilnehmerzugangsnetzen

In den letzten Jahren haben verschiedene P2P-Applikationen wie z.B. das File-Sharing eine weite Verbreitung erlangt. Deshalb wird zunächst untersucht, inwiefern gezieltes P2P-Routing hilft, P2P-Datenmassen besser zu bewältigen und die Netzwerkinfrastruktur zu entlasten. Wenngleich P2P-Netze oftmals mit dem illegalen Tausch lizenzrechtlichen Materials assoziiert werden, so sind die zugrunde liegenden Technologien vom Verwendungszweck losgelöst zu betrachten. Ferner studiert die vorliegende Forschungsarbeit daher Einsatzmöglichkeiten der P2P-Netzwerktechnologie in Teilnehmerzugangsnetzen

Dynamic Migration of Real-Time Traffic Flows in SDN-Enabled Networks

In this paper, we investigate the problem of dynamic migration for realtime traffic flows, which consists in accommodating new flows at runtime in SDN-enabled networks. We show results for two algorithms that can calculate direct and indirect flow migrations at runtime. Numerical results obtained on a FatTree network topology show that flow migration is typically required for networks with a modest number of flows, while direct flow migration is possible in about 60% of the cases

Realtime Publish/Subscribe for the Industrial Internet of Things

Publish/subscribe communication offers outstanding flexibility, but lacks the predictability required for guaranteeing (hard) realtime constraints in industrial environments such as future smart factories. In this paper, we review existing publish/ subscribe systems, identify their shortcomings, and derive research objectives for a converged realtime network infrastructure for the Industrial Internet of Things (IIoT) that is based on publish/subscribe and Software-Defined Networking (SDN)

Fast Publish/Subscribe Using Linux eBPF

In recent years, the requirements for publish/subscribe systems have changed enormously. Mainly, this is due to the vastly increasing number of smart objects, services, and apps being connected to the cloud and their growing demand for bandwidth and realtime message processing. Unfortunately, many publish/subscribe systems are hardly able to handle both necessary and available data rates when being built on conventional network stacks that suffer from significant system overhead. In this paper, we present a novel architecture for fast publish/subscribe that consists of an edge broker for preprocessing notifications and a cloud broker that leverages eBPF to efficiently process network packages and speed up notification delivery. We address limitations of eBPF, discuss different filter options, and quantify the achievable performance. The evaluation confirms a significant performance improvement of the eBPF-enabled cloud broker when compared to a conventional implementation

Simulation model for energy consumption and acoustic underwater communication of autonomous underwater vehicles

Recently, cooperative autonomous underwater vehicles (AUVs) have been deployed in application areas such as surveillance and protection of maritime infrastructures for inspection and monitoring purposes. These cooperative methodologies require wireless transmission of data between the different AUVs operating in the underwater environment. Communication over ranges exceeding 100 m exclusively relies on underwater acoustic communication. However, the propagating acoustic waves suffer from several challenges due to the presence of path loss, multi-path propagation, the slow and variant propagation speed, background noise, and Doppler distortion. Since the power supply of the AUVs is limited, communication must be very energy efficient and energy constraints have to be known to be able to plan the mission of AUVs. Due to the difficulties of real experiments, the modeling and simulation of the energy consumption and underwater acoustic communication play an essential role in studying and developing these systems. We provide a modular simulation model for the energy consumption and acoustic underwater communication of AUVs implemented in the network simulator OMNeT++ using the INET framework. More specifically, we extend several INET modules in such a way as to reflect the characteristics of AUVs and underwater communication. We study and analyze the AUVs’ energy consumption and dependence of the message quality on different properties such as those mentioned above

A Simulation Model for Investigating Clock Synchronization Issues in Time-Sensitive Networks

The IEEE 802.1 Time-Sensitive Networking (TSN) task force has set guidelines for IEEE 802.3 networks allowing deterministic realtime communication over Ethernet. To execute deterministic time-triggered scheduling operations, the network nodes need to be synchronized. One application of time synchronization is distributed data acquisition for the Wendelstein 7-X nuclear fusion experiment. Both the system control and the scientific evaluation of the experiments need measurement timestamps with accuracies in the nanosecond range. The TSN standard IEEE 802.1AS has specified the generalized Precision Time Protocol (gPTP) which executes the synchronization process. However, there are some issues that are not addressed in the standard such as the impact of clock skew and drift of network nodes on the number of resynchronizations needed to maintain the required synchronization accuracy. This paper introduces an OMNeT++ simulation model, which can be used to investigate clock synchronization issues in time-sensitive networks

Network and application design for reliable distributed systems

This habilitation thesis explores various possibilities for the network and application design of reliable distributed systems. Depending on the application, it is investigated how real-time capability as well as high scalability, accuracy, robustness, and performance can be achieved.In dieser Habilitationsschrift werden verschiedene Möglichkeiten für das Netz- und Anwendungsdesign zuverlässiger verteilter Systeme untersucht. In Abhängigkeit von der Anwendung wird untersucht, wie Echtzeitfähigkeit sowie hohe Skalierbarkeit, Genauigkeit, Robustheit und Leistung erzielt werden können