Time-Sensitive Networking (TSN) extends Ethernet to enable deterministic networking making it suitable for latency-sensitive industrial applications. To ensure bounded end-to-end delays and minimal jitter, a network-wide communication schedule with exclusively reserved transmission slots is enforced for time-triggered hard realtime traffic. While numerous scheduling methodologies exist for generating such schedules, their practical applicability remains uncertain. In this paper, we present a testbed for evaluating the real-world suitability of TSN schedules. We describe the hardware and software setup and demonstrate our evaluation methodology.

In Time-Sensitive Networking (TSN), Time-Aware Shaping facilitates the convergence of deterministic and lowpriority traffic in Ethernet networks. The allocation of bandwidth for low-priority traffic is crucial when scheduling timetriggered (TT) streams to prevent starvation and packet loss caused by queue congestion. This issue is particularly pertinent in online scheduling scenarios, where the deletion of streams can lead to schedule fragmentation. To prevent this issue, the time slots of the TT streams must be compressed to provide larger contiguous gaps for low-priority traffic in the schedule. In this paper, we present a novel heuristic approach for compressing schedules, which facilitates the grouping of time slots into units, thereby increasing the bandwidth for low-priority traffic and improving the schedulability of future streams. The proposed heuristic can be tailored to specific use cases through adaptive weighting, allowing a comprehensive evaluation of time slots according to the properties of the associated time slot units, TT streams, and the network.

Time-Sensitive Networking (TSN) is a key technology for converged industrial communication systems enabling the integration of traffic with diverse Quality of Service (QoS) requirements such as timeliness, throughput, and reliability. To ensure that all data streams meet their requirements, the Network Calculus (NC) allows to analytically derive worst-case performance estimations. In this paper, we model rate-constrained streams alongside time-triggered hard real-time traffic in a line topology. Additionally, we compare the analytical results with a simulation conducted in the OMNeT++ network simulator. Our comparison shows that the worst-case delay predicted by the NC is 3 to 4 times higher than the delay observed in a simulation. Similarly, the estimated backlog (i.e., the amount of data queued in TSN switches) is $\mathbf{2}$ to $\mathbf{3}$ times larger than the simulation results.

In the modern world, accurate crowd counting is integral to a multitude of applications, including urban planning, transportation management, and crowd control. The advent of opportunistic communication networks, which enable devices to sporadically exchange data in a decentralized fashion, has introduced a new set of challenges in crowd estimation. This paper delves into two opportunistic people counting protocols: UrbanCount and HeartBeatCount. UrbanCount, while a robust protocol in its own right, comes with certain limitations that hinder its real-world applicability. In response to these limitations, this paper introduces refinements to UrbanCount, making it more practical and effective. Additionally, a novel protocol called HeartBeatCount is presented, which significantly enhances crowd size estimation accuracy, particularly in sparse scenarios. Through an evaluation, we compare the performance of these protocols and conclude that HeartBeatCount offers a more resilient solution for opportunistic people counting in various real-world scenarios.

Time-Sensitive Networking (TSN) facilitates the implementation of realtime data traffic with deterministic delay and jitter in Ethernet networks. In its time-triggered communication variant, network paths as well as transmission time slots along the paths need to be planned and reserved for all data streams, respectively. Conventionally, such a feasible (i. e., realtime compliant) network schedule is computed and optimized offline, installed upon deployment, and cannot be changed anymore at runtime without stopping the communication. The latter becomes unsuitable for future industrial use cases with a growing demand for flexibility including schedule adjustments. In this paper, we present an online scheduler capable to incrementally integrate new streams at runtime and to adapt the existing schedule, if necessary, while retaining the realtime guarantees given to active streams. For this purpose, the scheduling heuristic identifies streams whose adjustment requires minimal reconfiguration efforts. In a thorough evaluation, we analyze the scheduler's trade-off between resource usage and schedule quality showing its suitability for diverse application scenarios.

Time-Sensitive Networking (TSN) disrupts realtime communication technology by making IEEE Ethernet realtime-capable. For time-triggered, hard realtime traffic, TSN provides standardized mechanisms to reserve communication paths as well as individual transmission time slots for data frames. By leveraging these means in a precomputed network schedule, TSN allows for bounded end-to-end delays and minimal jitter. Not being part of the IEEE standard, corresponding scheduling algorithms are an active field of research. Unfortunately, due to differing model assumptions, evaluation setups, and key metrics, a fair comparison of schedulers is impossible so far. In this paper, we present a systematic and reproducible approach to benchmark TSN schedulers. First, we provide a scheduler taxonomy that enables to cluster schedulers by their characteristics. Second, we analyze interactions of input parameters and scheduler results to derive a benchmarking parcour for quantitative comparisons. Finally, we use the approach to benchmark existing schedulers and show subtle interaction effects. This way, our approach enables—for the first time-comparability between schedulers, fueled by the public availability of our benchmarking scenarios.

The rising number of IoT systems deployed in production increases the risk of becoming a victim of costly attacks. The complex architecture of such systems increases their attack surface making the systems more vulnerable by attacks that can even paralyze production. For 2020, it is estimated that more than 30 billion IoT devices are in use worldwide; of which more than 5.8 billion in the industrial sector. It is therefore imperative today to have a threat modeling tool that examines all system components and assigns them a risk of being exposed. This paper proposes a novel ISO-compliant test procedure for the technical risk analysis of IoT systems since state-of-the-art methods are either not ISO-compliant or are not suitable for technical risk analyses. It is based on the generic threat model Microsoft STRIDE, which has been developed to consider and evaluate all system components. The test procedure is able to identify vulnerabilities and assigns a risk to them. It complies with ISO/IEC 27001 and implies ISO/IEC 27005 and ISO 31000. The threats are stored in a threat database and linked to countermeasures. The designed tool implementing the novel test procedure automatically proposes countermeasures for certain attacks to the user. The tool uses a learning database in which new insights can be entered during each risk analysis so that the tool is improved with each use. As proof of concept, an IoT system is analyzed for its risks and the high achievable accuracy of the proposed risk assessment is shown.

Future applications of the Industrial Internet of Things will increasingly depend on the timely exchange of information and data. Time-Sensitive Networking, which is currently being standardized, therefore extends switched Ethernet networks by realtime communication capabilities offering deterministic message delays. In its time-triggered communication variant, a network path needs to be planned for each realtime data flow and corresponding transmission time slots have to be reserved on the network links along that path. In this paper, we present the first joint mathematical model for path routing and time slot scheduling that combines multicast support with an individual transmission scheduling on each link along a flow's path. We provide a formalization as an Integer Linear Programming (ILP) problem and discuss several optimizations to significantly reduce the ILP solver's runtime without affecting the solution quality. In a thorough evaluation, we show the applicability of our approach and analyze the effects and trade-offs of different objective functions.

In Smart Buildings there is a large number of connected devices. Each of them is possibly vulnerable, so that an attacker could make use of a single smart device to run attacks in the Smart Building network. We propose a concept to partition the network into trust zones depending on the application layer, so that devices that are logically linked on application layer are able to communicate on MAC layer. A trusted device is used to bootstrap new devices and reconfigure existing trust zones. We restrict the communication as far as possible, so that the potential damage caused by a compromised device is limited. In principle, malicious behavior of devices could lead to an exclusion on MAC layer. The general concept is described using a typical IoT protocol stack containing IEEE 802.11s, IP, UDP/DTLS, and CoAP.

This survey addresses the question if existing realtime capable Internet technologies for wired communication can meet the requirements of future industrial IoT scenarios with a rising number of heterogeneous devices to be connected and increasing amounts of data to be exchanged in real-time. The development towards an industrial IoT is further referred to as Industry 4.0 in Germany and Industrial Internet in the USA, respectively. We first investigate selected widespread technologies at all layers of the ISO/OSI model with respect to their realtime capability, scalability and dynamic reconfiguration, standard compliance and platform complexity as well their capability to integrate non-real-time devices. On the one hand, we note that TSN technology at physical and link layer is standardized but exhibits very high platform complexity for the switches and is thus costly. Subsequently, it is hence discussed if purely software-based approaches can enable RT communication over Ethernet. Moreover, even though TSN-enabled network components can enforce real-time behavior, scheduling and routing algorithms for computing the respective network configuration are not part of the TSN standards. Those algorithms could be executed on a central SDN controller to achieve high performance and realtime capability, however, the scalability of such a centralized approach is limited by the fact that corresponding algorithms have exponential computational complexity. Hence, one of the future research directions outlined proposes to trade off distributed against centralized scheduling and routing approaches with regard to scalability and dynamic reconfiguration, real-time capability, and platform complexity. We conclude there is a need for the advancement of existing and for the development of new, possibly hybrid, real-time capable approaches that combine the advantages of centralized and distributed solution in order to meet all requirements.

Clock synchronization protocols such as the precision time protocol (PTP), which are used to synchronize components of distributed systems, are fundamental to enable timed and coordinated activities, e.g., in real-time applications within the industrial Internet of things (IIoT). In theory, PTP is able to achieve a precision on the order of nanoseconds. However, its practical accuracy remains limited by packet delay variations. In this paper, we hence present a novel approach to increase the synchronization precision of PTP. Our approach (PTP-LP) relies on PTP to obtain precise hardware timestamps taken during multiple synchronization periods. These timestamps establish the constraints for a Linear Programming (LP) solver that is used to estimate the clock differences between devices. Moreover, we propose the heuristic PTP-H that achieves comparable accuracy but is less computationally complex. We evaluate PTP-LP and PTP-H in comparison with two state-of-the-art approaches under various conditions in terms of clock stabilities and packet delay distributions. PTP-LP and PTP-H are fully compatible with existing standards and show to be in particular robust to varying packet delays. Especially, PTP-LP outperforms previous approaches in presence of a stable hardware clock and unknown non-negligible network delay, which are both realistic working conditions.

WLAN mesh networks are one of the key technologies for upcoming smart city applications and characterized by a flexible and low-cost deployment. The amendment IEEE 802.11s introduces low-level mesh interoperability at the WLAN MAC layer. On the physical layer, IEEE 802.11n introduced major improvements such as HT data rates, MIMO techniques, and frame aggregation. However, building large-scale 802.11n/s testbeds and reproducible setups is challenging and costly. On the other hand, existing attempts for down-scaling real-world setups are limited to works without support for 802.11n and 802.11s. We therefore present Mini-Mesh, a miniaturized indoor 802.11n/s testbed. Following a transmission range scaling approach, we deploy a 6×6-node mesh grid on an area of only 1 m2. We validate the applicability of our method via comparative measurements, exhibiting a deviation of less than 6 % between a scaled indoor and unscaled outdoor setup. Based on these results, we parameterize a path loss model helping us to estimate outdoor dimensions for arbitrary indoor mesh topologies.

Clock synchronization is an important issue in wired and wireless networks as a common time basis is essential for coordinated activities of nodes in distributed systems. Typical applications demanding precise synchronization are Industrial Internet scenarios having real-time constraints, Wireless Sensor Networks (WSNs) where the nodes communicate only for a short period and can sleep the remaining time to save energy, approaches based on Time Division Multiple Access (TDMA), and distributed measurements. The basic idea of our approach is to estimate all delays in a network. As a result, we can estimate the one-way delay between a reference node and all other nodes in the network. Consequently, we can use broadcast messages to synchronize the entire network. Utilizing a novel measurement method and a Java prototype implementation, we show that our approach achieves a high precision (≈ 123 μβ). Furthermore, it is highly scalable and platform independent. As our synchronization approach operates at the application layer, it is suitable for both wired and wireless networks.

Various industrial control applications have stringent end-to-end latency requirements in the order of a few milliseconds. Software-defined networking (SDN) is a promising solution in order to meet these stringent requirements under varying traffic patterns, as it enables the flexible management of flows across the network. Thus, SDN allows to ensure that traffic flows use congestion-free paths, reducing the delay to forwarding and processing delays at the SDN nodes. However, accommodating new flows at runtime is under such a setting challenging as it may require the migration of existing flows, without interrupting ongoing traffic. In this paper, we consider the problem of dynamic flow migration and propose a polynomial time algorithm that can find a solution if direct flow migration is feasible. We furthermore propose an algorithm for computing both direct and indirect flow migration and prove its correctness. Numerical results obtained on a FatTree network topology show that flow migration is typically necessary for networks with a moderate number of flows, while direct flow migration is feasible in around 60% of the cases.

The new standard IEEE 802.11s enables vendor-independent wireless mesh networks based on the 802.11 WLAN technology. Transmission Control Protocol (TCP) is the most widespread transport protocol for reliable data delivery and still the basis for many network applications. TCP supports different mechanisms for flow and congestion control. However, designed for wired networks, it does not consider the dynamics of wireless networks and especially multi-hop wireless mesh networks. In addition, 802.11s provides own mechanisms such as Automatic Repeat Request (ARQ) for frame retransmissions to hide wireless loss from the upper layers. Being transparent to each other, retransmission schemes on both layers may interfere and operate redundantly, if not properly adjusted. We study the effects of ARQ retry limit variation on TCP throughput in a real-world multi-hop 802.11s test bed. As a result, we suggest ARQ adaptation based on the 802.11s standard's Airtime Link Metric (ALM) for path selection, serving as indicator for overall frame travel time. Our proposed approach solely relies on standard features and imposes no modifications to 802.11s or TCP.

The new standard amendment IEEE 802.11s enables low-level interoperability for future WLAN mesh networks. Support of the Hybrid Wireless Mesh Protocol (HWMP) and the Airtime Link Metric (ALM) for MAC-layer routing is mandatory. Its default distance vector routing mode facilitates scalability but also results in a limited network view per mesh node. Moreover, mesh mechanisms operate transparently to higher layers which makes the management and optimization of 802.11s networks a challenging task. Available on every standard-compliant node, ALM offers the potential to derive mesh topology information. We present AKadeMesh (Adaptive Kad-enhanced Mesh), a cross-layer approach specifically designed for 802.11s networks. It is based on the P2P protocol Kad and dynamically adapts its logical overlay to the physical mesh underlay by directly considering ALM. The resulting topology-aware P2P overlay is used to realize logical clustering for the distributed management of 802.11s networks, thereby maintaining unrestrained interoperability to the mesh standard. Our solution was implemented and evaluated in a real-world test bed. Results demonstrate its practical feasibility and verify the expected clustering benefit.

Real-time systems play a major role in the realm of industrial automation. It is predicted for the number of smart interconnected devices that participate in such systems to grow significantly in the future. This development is also referred to as Industrial Internet of Things (IIoT) or Industry 4.0. The high number of devices results in highly distributed applications. Therefore, it is no longer sufficient for each device to be real-time capable. In fact, the influence of the communication on the overall timing behavior of the applications grows. Taking this into account, a variety of real-time capable Ethernet approaches called Industrial Ethernet (IE) emerged. However, the established IE solutions rely on proprietary hardware and/or non standard conform protocol adaptations. This leads to very expensive hardware and incompatibilities with other IE solutions or common Ethernet, and thus degrades the interoperability. HaRTKad describes a purely software-based P2P approach that allows deterministic communication over common Ethernet. Although it solely relies on well-known standards and allows real-time communication, it suffers from a multitude of problems. In this paper, the low network utilization, the handling of hash collisions and the traffic prioritization are revealed as the most significant limitations of HaRTKad and possible solutions to these problems are presented.

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.

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.

For the realization of decentralized communication infrastructures, P2P technology offers an excellent technological foundation to complement or replace existing centralized structures, which take the client-server network model as a basis. In particular, the distributed hash table-based P2P network Kad impresses with high lookup performance, scalability, and resilience against failures and attacks. In addition to these advantages, the Kad protocol needs an extension in terms of its lookup to allow for lookup determinism in an a priori unknown Kad network. Therefore, this paper introduces a dynamic search tolerance, which adapts itself to any network configuration autonomously at runtime. The search tolerance is periodically calculated and all nodes are provided with the updated value. Thereby, the Kad protocol meets the demands for deterministic lookups, which enables dependable and efficient data retrieval, qualifying it as reliable basis of communication infrastructures in, e.g., real-time environments. Results show the high performance of the proposed algorithms for a Kad network with up to 50,000 nodes.

Software-defined networking (SDN) is a principle for the flexible configuration of networks, which recently has aroused an increasing interest of researchers and companies. Today, the operation and configuration of networks as well as their adaptation to changing requirements represent a major challenge if legacy network management protocols are used due to their inability to provide network-wide configuration. Compatibility issues with legacy protocols or even proprietary protocols have further contributed to hardly reconfigurable and inefficient networks and thus prepare the way for the new concept called SDN. SDN implementations are mainly in the data center today. Implementations will find their way into broader networking applications over the next few years. However, even automation networks with highest QoS requirements can benefit from SDN support by achieving significantly more devices that meet these requirements. Therefore, this paper addresses the emulation of SDN-supported automation networks to examine possible design options. Limitations and possibilities when using the popular and widely accepted SDN emulator Mininet are analyzed.

In recent years, cloud computing, which provides users with network resources such as memory and computing power depending on the users' needs, has gained enormously in importance. Providers such as Amazon allow the users to access their cloud storage and computing resources by different interfaces. In this regard, guaranteeing compatibility is a severe issue as many different proprietary interfaces exist for accessing data in different clouds. The solution to this problem is the RESTful Cloud Data Management Interface (CDMI) standard, which has passed the ISO audit as first standard and is therefore evolving into the most common standard for accessing clouds. This paper investigates the combination of CDMI with a P2P-based storage and computing back-end in order to realize a self-organizing cloud for distributed data storage and processing called DuDE-Cloud. The basis is the self-organizing hash table (DHT)-based P2P storage and computing back-end called DuDE, which utilizes the DHT protocol Kad. DuDE is able to bundle existing storage and computing resources of different devices dynamically and has already proven its advantageous performance over centralized solutions. In a test scenario, resources of DuDE-Cloud were successfully accessed through CDMI using a GUI front-end thereby proving the proper functionality. As a result, a resilient high-performance distributed cloud solution is available that is compatible with other clouds.

The broad availability of WLAN-capable off-the-shelf hardware lets WLAN mesh networks appear as promising technology for future distributed wireless applications. Featuring automatic device discovery, interconnection and routing, they provide a higher scalability, flexibility, and robustness compared to common centralized WLAN infrastructures. Besides these advantages, characteristics such as variable network topologies and link qualities imply new technical challenges for administration and real-world operation. Adopted in late 2011, IEEE 802.11s appears as new WLAN standard amendment, enabling vendor-independent mesh networks based on the widespread WLAN technology. However, network monitoring and management fall out of the standardization scope and are therefore not specified. In this paper, we present a novel 802.11s management solution based on the SNMP protocol. It covers dynamic mesh bootstrapping, error recovery, status monitoring and remote configuration. The presented solution was implemented and evaluated in a real-world testbed comprising more than 10 mesh nodes.

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.

The domain name system (DNS) includes infrastructures deployed by Internet service providers (ISPs) and third-party suppliers to ensure high responsiveness, resilience, and load sharing. This equipment implies high effort and energy for 24/7 operation. To facilitate cost reductions in this regard, P-DONAS—a peer-to-peer (P2P)-based DNS—organizes access nodes (ANs) of an ISP’s access network, which possess available resources, into a decentralized, self-organizing distributed hash table--based P2P network. Each AN acts as traditional DNS server and solely stores a piece of DNS data. DNS requests issued to an AN are resolved via P2P lookups while maintaining full compatibility with traditional DNS. The article discusses the application of P-DONAS as both a complement and an alternative to traditional DNS. Results from both simulations and a practical test arrangement prove P-DONAS’ high scalability and its performance comparable to that of a commercial DNS name server relieving this name server by 53% to 75% of DNS traffic.

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.

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.

Web Services are becoming more and more relevant also in the domain of embedded devices as they are becoming an important aspect of the Internet of Things. Embedded devices, especially in the field of automation, require real-time behavior. The Devices Profile for Web Services defines WS-Standards for embedded systems. The WS-Eventing is one of this standards within DPWS and enables the distributions of events. However, WS-Eventing has a scalability problem as in ad-hoc networks the notification is transmitted sequential by an event source. Under these circumstances, it is not suitable for large-scale networks with a high amount of devices. Therefore, a new approach is presented to solve this issue by acquiring helping devices. The communication is only based on unicast IP communication and thus is easy to integrate into automation infrastructures and could be established over several subnets. This approach has been investigated with an experimental setup and shows the high scalability compared to the original notification mechanism. Additionally, the real-time capability is given due to the chosen platform and real-time operating system. Thus, the new approach enables the idea of Internet of Things in automation scenarios.

Web service technology becomes popular in a growing number of applications. The field of application reaches from smart home over factory automation up to smart cities. One of the main aspects of this technology is a dynamic device and service discovery. For this purpose, the WS-Discovery standard is used. WS-Discovery supports two modes: an infrastructure-based and an ad hoc mode. The infrastructure-based mode requires a service proxy, which represents a single point of failure. The ad hoc mode is based on the multicast and static response time values. Therefore, it shows a low scalability. In this work, we present a novel discovery approach, which bases on distributed hash tables (DHTs). DHTs are often utilized in peer-to-peer networks and represent a well-established technology. The search for devices and services is performed using hash values. The benefit of this approach is a high scalability, deterministic behavior, and flow control. The suggested approach can be applied for networks of any size. Since this approach uses unicast messages, it is not limited to local networks allowing the device and service discovery over multiple subnets or even over the Internet.

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 perceptron's 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.

Device and service discovery is an essential part of automation networks in order to ensure the interoperability of devices and Plug&Play functionalities. Embedded Web services such as Devices Profile for Web Services are an upcoming technology for building and factory automation. For ad hoc discovery, the WS-Discovery standard is used. This approach avoids single points of failures. However, it shows low scalability due to static response time values. The rising number of devices leads to an increasing network load and especially to an increasing device processing load as a result of the discovery process. In this work, we evaluate the issues of ad hoc service discovery and suggest an optimized algorithm for dynamic data rate reduction in large scale networks. Moreover, the suggested improvements allow reducing peak data rates by more than 50% for constant timing parameters. Using the suggested approach, the ad hoc discovery can be applied in any network size. The desired peak data rates or response times of the system can be significantly reduced and dynamically adjusted according to the desired values. This approach guarantees a scalable ad hoc discovery mechanism and is backward compatible with legacy equipment.

The P2P-based system for the distributed storing of session data of Internet service providers' access nodes called P2P-based storage platform is presented. Session data is continuously changing due to customers connected to access nodes, i.e., it is highly volatile. However, it has to be stored persistently as it is required for data forwarding, traffic filtering, and deriving statistics. Failing access nodes must be able to restore their data after reentering the network. Today, the session data is stored in the access nodes' flash memory, which is limited in life time and size and intended for other purposes. Contrary, the P2P-based storage platform allows to store session data in the access nodes' available RAMs connected by the distributed hash table-based P2P network Kad. A Kad network consisting of 8,000 access nodes for distributed storage of session data is setup for simulation. The simulation results show the traffic overhead to be minimal, linear scalability, and prove the high availability of the stored session data.

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.

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.

This demonstration shows the hardware prototype of the IPclip (IP calling line identification presentation) mechanism for IPv6 networks. IPclip is a mechanism, which provides Trust-by-Wire in IP-based networks by adding trustworthy location information to IP packets. It is implemented on an FPGA development board and configurable at runtime via a graphical configuration tool. We show IPclip's basic functionality in a localization scenario using an analysis tool and Google Earth and discuss several application scenarios during the demonstration.

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 Internet's 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 threat's origin by using a set of location information.

During the last decades, the Internet has steadily developed into a mass medium. The target group radically changed compared to, e.g., the 90s. Because virtually everyone has access to the Internet, threats due to insecurity and anonymity reach critical levels and have to be tackled by both carriers and Internet Service Providers. Regaining trust-by-wire, comparable to classic fixed line telephones, could mitigate or even solve problems like Spam, Phishing, and the localization of VoIP emergency calls. This paper presents the hardware implementation of a new and highly flexible solution-Internet protocol-calling line identification presentation-which provides additional support for new services to restore peoplepsilas confidence into the Internet. Supported services are VoIP emergency calls, Spam detection and prevention, and phishing prevention. Already in the access network, the hardware adds unambiguous location information on the packetpsilas origin to IP packets. We document the hardware design of the solution. Furthermore, hardware consumption and performance of a prototype are presented.