Peter Danielis

Survey on real-time communication via ethernet in industrial automation environments

For companies in the automation industry, the development of real-time Ethernet to connect devices is of high economic interest to replace conventional fieldbus systems. Therefore, many approaches for adapting Ethernet to real-time requirements come from industrial applications. This is a challenging task as the original Ethernet standard IEEE 802.3 was not designed for real-time data transmission. Likewise, protocols basing on Ethernet like TCP, UDP, and IP do typically not consider real-time requirements. Hence, adaptations on several OSI layers become necessary to make the industrial system meet hard real-time requirements. For this purpose, a multitude of realtime capable Industrial Ethernet systems has been developed, which solve the problems of standard Ethernet- and TCP/IP- or UDP/IP-based communication in a variety of ways. This paper gives a summary of different Industrial Ethernet protocols for the real-time data transmission via Ethernet in automation environments. Advantages and disadvantages of these protocols are analyzed with regard to their sustainability in terms of their realtime capability, reliability, scalability, self-configuration of the network, and hardware requirements. Against the background of connected devices tremendously growing in number and computational power in the prospective “Industrial Internet”, consequences for future developments are drawn.

HaRTKad: A hard real-time Kademlia approach

The Internet of Things is becoming more and more relevant in industrial environments. As the industry itself has different requirements like (hard) real-time behavior for many scenarios, different solutions are needed to fulfill future challenges. Common Industrial Ethernet solution often leak scalability, flexibility, and robustness. Most realizations also require special hardware to guarantee a hard real-time behavior. Therefore, an approach is presented to realize a hard realtime network for automation scenarios using Peer-to-Peer (P2P) technology. Kad as implementation variant of the structured decentralized P2P protocol Kademlia has been chosen as base for the realization. As Kad is not suitable for hard real-time applications per se, changes of the protocol are necessary. Thus, Kad is extended by a TDMA-based mechanism. Additionally, to evaluate the performance an prototype is presented, which is realized on an embedded platform with a real-time operating system. Thereby, with the presented approach and a realized prototype it is possible to investigate the performance of a Kad network with hard real-time capabilities.

DuDE: A distributed computing system using a decentralized P2P environment

The P2P-based system for the distributed computing of statistics called DuDE is presented. High scalability and failure resilience features of P2P are exploited to achieve a high-performance distributed system, which avoids the bottlenecks of a centralized computing system. To ensure high data availability, a sophisticated algorithm for distributed data storage is integrated. Furthermore, an algorithm for global peer discovery is presented, which allows for finding all data assigned to peers without the need for a central instance. For the realization of DuDE, common working stages of distributed computing are extended to enable a highly scalable computing system based on P2P technology. Generated results from a test system show a nearly perfect linear speedup for distributed computing as well as high processor and memory relief compared to a centralized solution.

Time synchronization in the DHT-based P2P network Kad for real-time automation scenarios

In this paper, an approach to synchronize the P2P network Kad to be applied in automation scenarios is presented. The approach bases on a deterministic algorithm to synchronize the network, which is required for hard real-time applications. Todays Industrial Ethernet solutions include and support machine to machine communication in automation scenarios. However, instead of allowing direct communication, the communication relies on centralized structures, which are deficient in resilience and scalability However, instead of allowing direct communication, the communication relies on centralized structures. The presented decentralized approach benefits from nodes helping to synchronize the network. However, the higher the number of helping nodes the higher is the time deviation on the nodes of the network, which contrary results in a higher time error. Therefore, a trade-off between synchronization performance and time error has to be determined to meet predefined constraints depending on the application scenario. Moreover, the individual clock drift of every device is considered to define necessary re-synchronization intervals of the network. Additionally, the optimum number of nodes to synchronize the Kad based network has been identified and the resulting synchronization performance and generated traffic are determined. Furthermore, an approach is presented to handle the dynamic churn of nodes.

Application-aware industrial ethernet based on an SDN-supported TDMA approach

In industrial automation environments, networks providing a reliable and timely data delivery are required. Fulfilling this need, Industrial Ethernet (IE) systems have established as an important networking technology in many application areas. Although there are several IE solutions on the market, all of these systems have notable drawbacks, like limited scalability or the introduction of a Single Point of Failure (SPoF). Therefore, we propose a novel IE system that is based on Software Defined Networking (SDN). Originally meant for data center and IT networks, the SDN concept offers features like central network management functions and a fine-grained traffic control that allows to support many applications with diverse requirements even in the same network. Thereby, SDN is also perfectly suited for complex automation environments. To guarantee RT data transmission as well as scalability and an efficient resource usage, our IE system uses a Medium Access Control (MAC) scheme that is based on a Time Division Multiple Access (TDMA) mechanism that is extended by simultaneous data transmissions on physically separate links. The enhanced TDMA mechanism is configured by a joint routing and scheduling algorithm that takes application requirements into account. Our theoretical analysis as well as results achieved with a prototype implementation of the system confirm the applicability of our concept in demanding automation environments with applications that require a worst case communication latency below 1 ms.

Trust-by-Wire in packet-switched networks: Calling line identification presentation for IP

During the last decades, the Internet has steadily developed into a mass medium with millions of users. On the one hand, newfangled services replace traditional ones. Naturally, these are thereby expected to offer at least the same features as their classical pendants, e.g., when VoIP replaces traditional fixed line telephone networks. On the other hand, the requirements on network infrastructures and services have changed. A reason for that is the lack of Trust-by-Wire in packet-switched IP networks. In traditional telephone networks, a phone number directly coheres with a physical line. This direct relationship is not given in modern packet-switched IP networks. An IP address does not identify a physical line! This paper presents a new mechanism, which guarantees Trust-by-Wire in packet- switched IP networks -called Internet Protocol-Calling Line Identification Presentation (IPclip). Unambiguous and trustworthy location information is added on the IP level. Firstly, IPclips general functionality is presented. Secondly, we discuss IPclip in the light of location-aware emergency calls in nomadic VoIP environments.

A Highly Integrable FPGA-Based Runtime-Configurable Multilayer Perceptron

In this paper, a highly integrable Field Programmable Gate Array-based hardware design of multilayer perceptron as a realization of an artificial neural network is presented. Such a hardware solution ensures a deterministic behavior required for any hard real-time compositions. The integration into existing systems is achieved by the application of UDP/IP. %A developed protocol enables the hardware solution to act as a stand-alone device with no need for an additional host PC. Additionally, the presented design is highly flexible due to a parameterizable multilayer perceptron approach. However, most reconfigurations usually require a hard coded reimplementation, resynthesis, and the download of a new bit file to the target platform, which also requires an additional host PC. Contrary with the presented solution, it is possible to configure the multilayer perceptrons parameters during runtime via a software interface. This approach allows the multilayer perceptron to be adapted to nearly any application. The developed design combines the flexibility of a software solution to generate and comfortably reconfigure the multilayer perceptron as well as the high performance of a hardware solution. %The investigation of hardware utilization and performance of a running prototype stützt%Finally, the hardware utilization and performance are investigated. As proof of concept, a running prototype has been realized, which shows the design to be highly flexible and with good performance while the hardware resource consumption is kept minimal.

Countering phishing threats with trust-by-wire in packet-switched ip networks - a conceptual framework

During the last years, the Internet has grown into a mass-medium for communication and information exchange. Millions of people are using the Internet for business and in social life. Users can be reached easily and cost-effectively. Unfortunately the Internets open structure is the reason for its frequent misuse for illegal and criminal actions such as dissembling phishing attacks. Thus, anti-phishing techniques are needed to recognize potential phishing threats. But mostly these techniques are only of reactive nature, are soon circumvented by expert frauds, or are not efficient enough. This paper describes an anti-phishing framework. A concept for trust management and a mechanism called IPclip are presented. The main idea of IPclip is to guarantee trust-by-wire in packet-switched networks by providing trustworthy location information along with every IP packet. This information is used as supplementary and trustworthy trigger to identify potential phishing threats. Besides, the proposed framework allows for tracing the threats origin by using a set of location information.

ViPMesh: A virtual prototyping framework for IEEE 802.11s wireless mesh networks

WLAN mesh networks are characterized by their flexible and low-cost deployment, scalability, and self-healing capabilities. The new WLAN standard IEEE 802.11s introduces low-level mesh interoperability. However, building large-scale real-world test beds and reproducible setups is challenging and costly. In the majority of research works, network simulation is preferred over practical measurements. Here, the main disadvantage exists in simplified device and protocol models restricting the comparability to practical implementations. In contrast, using device emulation still requires the simulation of wireless channel and environment models. Consequently, a combination of both emulation and simulation is needed to enable virtual prototyping of real applications and protocols in WLAN mesh networks. Nevertheless, the computation of complex wireless channel effects requires a decoupling of wall clock and simulation time. Therefore, we present ViPMesh, a virtual prototyping framework for IEEE 802.11s and its Linux reference implementation. ViPMesh relies on WLAN device emulation and nested virtualization using QEMU and Linux containers to support the analysis of real applications on top of an unmodified protocol stack. Adopting an alternative time source approach for QEMU, ViPMesh acts as discrete-event simulator. It further integrates channel and environment models with support for IEEE 802.11n MIMO techniques, high throughput modes, multi-channel operation, and node mobility. To the best of our knowledge, this is the first approach that combines the IEEE 802.11s reference implementation with the described simulation features. The functionality of ViPMesh is demonstrated in different example scenarios.

Extensive analysis of the Kad-based distributed computing system DuDE

The distributed computing of data is a challenging task in terms of the self-organizing task distribution and computing, especially if distributed computing systems are becoming very large and complex. Therefore, the distributed hash table (DHT)-based P2P system called DuDE has been developed to compute statistics of access nodes of Internet service providers in an efficient way. DuDE exploits the high failure resilience and scalability features of the DHT network Kad to achieve a high-performance distributed system, which avoids the bottlenecks of a centralized computing solution. To ensure highly available data, Reed-Solomon codes for reliable distributed data storage are utilized. For implementing DuDE, usual working steps of distributed computing have been extended to realize a highly scalable computing system. We have developed a simulation model for a large-scale DuDE network consisting of up to 9,000 access nodes for computing statistics. In this paper, simulation results are presented, which demonstrate that DuDE is able to almost linearly accelerate the distributed computing compared to a centralized solution while introducing low traffic overhead.