МЕТОДИКА ПОЛУЧЕНИЯ ОБОБЩЕННЫХ СТАТИСТИЧЕСКИХ ХАРАКТЕРИСТИК СЕТЕВОГО ОБОРУДОВАНИЯ ДЛЯ СОЗДАНИЯ ИМИТАЦИОННЫХ МОДЕЛЕЙ

The research is devoted to the problem of the development models of network equipment that precisely reproduce the operation of real equipment by the time characteristics.Aim. This research is aimed at developing a methodology that allows you to quickly obtain models that statistically coincide in the behavior of the selected parameters with real measured equipment on existing open modeling systems.Methods. To obtain the performance parameters and time characteristics of the real equipment, an approach was proposed, which includes experiment planning to compute the characteristics for a wide range of input traffic intensities. In addition, the approach describes the connection scheme and equipment configuration including external switch control to test the effect of various settings on the performance and packet processing times. It also includes the scripts to automate the creation of traffic test sets with the required parameters of time distribution between the packets as well as the scheme of connection through the container services and receiving traffic dumps. The approach does not include the testing of the output queues operation because the goal was to investigate and transfer into the model processes, which occur before the frames are placed in the outgoing interface queues. An open-source Omnet++ software was used as a modeling environment.Results. We studied the structure of its existing switch model and identified disadvantages that affect the accuracy and reliability of the results. In addition, we proposed an approach for implementing model delay lines based on the interpolation of time parameter tables obtained from real data for the required combination of traffic parameters and inbound interfaces. To test the developed approaches, a test bench on real equipment was assembled, and an experimental research plan was developed. Finally, an automated testing script was implemented according to a given plan. Testing was carried out in the conventional frame switching mode as well as in the switching mode based on OpenFlow tables. In addition, the time characteristics of the intermediate equipment were also obtained in order to take into account their influence on the experimental results. Based on them, a table of parameters was computed for the processing delay line in the model, and the experiment was conducted on the model in Omnet++. Since the obtained samples in the statistical analysis showed the types of distributions that are different from the 3 normal and exponential, the statistical Mann–Whitney U-test was used to compare the mean values.Conclusion. The results obtained at a significance level of 0.05 confirmed the efficiency of this approach for models that more accurately describe the temporal characteristics of the traffic processing in network equipment.Работа посвящена проблеме разработки моделей сетевого оборудования, которые точно воспроизводят работу реального оборудования по временным характеристикам.Цель исследования. Данное исследование направлено на разработку методики, которая позволяет быстро получать модели, статистически совпадающие по поведению выбранных параметров с реальным измеренным оборудованием на существующих открытых системах моделирования.Методы. Для получения параметров производительности и временных характеристик реального оборудования создана методика, включающая планирование эксперимента для получения статистических данных в широком диапазоне входных интенсивностей трафика, конфигурацию и схему соединения оборудования, включающую внешнее управление коммутатором для тестирования влияния различных настроек на производительность и время обработки пакета, скрипты для автоматизации создания тестовых наборов трафика с требуемыми параметрами распределения времени между пакетами, схему подключения через контейнерные службы и схему съема дампов трафика. В методику не вошло тестирование работы выходных очередей, целью было исследовать и перенести в модель процессы, происходящие до помещения фреймов в исходящие очереди интерфейсов. В качестве среды моделирования использовался пакет с открытым исходным кодом Omnet++.Результаты. В работе изучена структура существующего модельного коммутатора Omnet++, выявлены недостатки, влияющие на точность и достоверность результатов, предложен метод реализации линий модельной задержки на основе интерполяции таблиц временных параметров, полученных по результатам реальных данных для требуемого сочетания параметров трафика и входящих интерфейсов. Для апробации разработанных подходов разработан тестовый стенд на реальном оборудовании, сформирован план экспериментальных исследований, реализован скрипт автоматического тестирования по заданному плану, проведено тестирование в режиме обычной коммутации фреймов и в режиме коммутации на основе таблиц Openflow. Также получены временные характеристики промежуточного оборудования для учета их влияния на результаты эксперимента. По полученным результатам проведен эксперимент на модели в среде Omnet++. Поскольку полученные выборки при статистическом анализе показали виды распределений, отличные от нормальных и экспоненциальных, для сравнения средних использовался статистический U-критерий Манна–Уитни

Software-Defined Networks Supporting Time-Sensitive In-Vehicular Communication

Future in-vehicular networks will be based on Ethernet. The IEEE Time-Sensitive Networking (TSN) is a promising candidate to satisfy real-time requirements in future car communication. Software-Defined Networking (SDN) extends the Ethernet control plane with a programming option that can add much value to the resilience, security, and adaptivity of the automotive environment. In this work, we derive a first concept for combining Software-Defined Networking with Time-Sensitive Networking along with an initial evaluation. Our measurements are performed via a simulation that investigates whether an SDN architecture is suitable for time-critical applications in the car. Our findings indicate that the control overhead of SDN can be added without a delay penalty for the TSN traffic when protocols are mapped properly.Comment: To be published at IEEE VTC2019-Sprin

DoS Protection through Credit Based Metering -- Simulation-Based Evaluation for Time-Sensitive Networking in Cars

Ethernet is the most promising solution to reduce complexity and enhance the bandwidth in the next generation in-car networks. Dedicated Ethernet protocols enable the real-time aspects in such networks. One promising candidate is the IEEE 802.1Q Time-Sensitive Networking protocol suite. Common Ethernet technologies, however, increases the vulnerability of the car infrastructure as they widen the attack surface for many components. In this paper proposes an IEEE 802.1Qci based algorithm that on the one hand, protects against DoS attacks by metering incoming Ethernet frames. On the other hand, it adapts to the behavior of the Credit Based Shaping algorithm, which was standardized for Audio/Video Bridging, the predecessor of Time-Sensitive Networking. A simulation of this proposed Credit Based Metering algorithm evaluates the concept.Comment: If you cite this paper, please use the original reference: P. Meyer, T. H\"ackel, F. Korf, and T. C. Schmidt. DoS Protection through Credit Based Metering - Simulation Based Evaluation for Time-Sensitive Networking in Cars. In: \emph{Proceedings of the 6th International OMNeT++ Community Summit}. September, 2019, Easychai

SDN4CoRE: A Simulation Model for Software-Defined Networking for Communication over Real-Time Ethernet

Ethernet has become the next standard for automotive and industrial automation networks. Standard extensions such as IEEE 802.1Q Time-Sensitive Networking (TSN) have been proven to meet the real-time and robustness requirements of these environments. Augmenting the TSN switching by Software-Defined Networking functions promises additional benefits: A programming option for TSN devices can add much value to the resilience, security, and adaptivity of the environment. Network simulation allows to model highly complex networks before assembly and is an essential process for the design and validation of future networks. Still, a simulation environment that supports programmable real-time networks is missing. This paper fills the gap by sharing our simulation model for Software-Defined Networking for Communication over Real-Time Ethernet (SDN4CoRE) and present initial results in modeling programmable real-time networks. In a case study, we show that SDN4CoRE can simulate complex programmable real-time networks and allows for testing and verifying the programming of real-time devices.Comment: If you cite this paper, please use the original reference: T. H\"ackel, P. Meyer, F. Korf, and T. C. Schmidt. SDN4CoRE: A Simulation Model for Software-Defined Networking for Communication over Real-Time Ethernet. In: Proceedings of the 6th International OMNeT++ Community Summit. September, 2019, Easychai

Сравнение характеристик протоколов маршрутизации в беспроводных DTN сетях для гибридной модели подвижности узлов

Для гибридной модели подвижности узлов в DTN сети представлены результаты имитационного моделирования популярных протоколов маршрутизации в DTN беспроводных сетях. Исследовалась вероятность доставки сообщения и среднее время доставки сообщения. Имитационная модель реализована в системе имитационного моделирования OMNeT++. В результате имитационных экспериментов установлено, что характер перемещения узлов, который имеет периодическую повторяемость, имеет влияние на эффективность протоколов маршрутизации, использующих различные принципы определения маршрута

Simulative Analysis with QRED to Decrease Packet Loss

Communication networks are facing packet loss at routers, where different approaches are used to reduce. Similarly RED is one of them, that existing RED [1] [2] algorithm and its variants are found in flow controlling. For minimizing dropping of packets and reducing buffer overflow. This paper propose a new routing algorithm in which additional FIFO controlled queue buffer before existing RED algorithm, to increases performance and throughput of the router. It is experimented and improvements in results are shown with help of OMNet++

A QoS Aware Approach to Service-Oriented Communication in Future Automotive Networks

Service-Oriented Architecture (SOA) is about to enter automotive networks based on the SOME/IP middleware and an Ethernet high-bandwidth communication layer. It promises to meet the growing demands on connectivity and flexibility for software components in modern cars. Largely heterogeneous service requirements and time-sensitive network functions make Quality-of-Service (QoS) agreements a vital building block within future automobiles. Existing middleware solutions, however, do not allow for a dynamic selection of QoS. This paper presents a service-oriented middleware for QoS aware communication in future cars. We contribute a protocol for dynamic QoS negotiation along with a multi-protocol stack, which supports the different communication classes as derived from a thorough requirements analysis. We validate the feasibility of our approach in a case study and evaluate its performance in a simulation model of a realistic in-car network. Our findings indicate that QoS aware communication can indeed meet the requirements, while the impact of the service negotiations and setup times of the network remain acceptable provided the cross-traffic during negotiations stays below 70% of the available bandwidth

Simulation of Mixed Critical In-vehicular Networks

Future automotive applications ranging from advanced driver assistance to autonomous driving will largely increase demands on in-vehicular networks. Data flows of high bandwidth or low latency requirements, but in particular many additional communication relations will introduce a new level of complexity to the in-car communication system. It is expected that future communication backbones which interconnect sensors and actuators with ECU in cars will be built on Ethernet technologies. However, signalling from different application domains demands for network services of tailored attributes, including real-time transmission protocols as defined in the TSN Ethernet extensions. These QoS constraints will increase network complexity even further. Event-based simulation is a key technology to master the challenges of an in-car network design. This chapter introduces the domain-specific aspects and simulation models for in-vehicular networks and presents an overview of the car-centric network design process. Starting from a domain specific description language, we cover the corresponding simulation models with their workflows and apply our approach to a related case study for an in-car network of a premium car

Phasing of Periodic Tasks Distributed over Real-time Fieldbus

In designing a distributed hard real-time system, it is important to reduce the end-to-end delay of each real-time message in order to ensure quick responses to external inputs and a high degree of synchronization among cooperating actuators. In order to provide a real-time guarantee for each message, the related literature has focused on the analysis of end-to-end delays based on worst-case task phasing. However, such analyses are too pessimistic because they do not assume a global clock. With the assumption that task phases can be managed by using a global clock provided by emerging real-time fieldbuses, such as EtherCAT, we can try to calculate the optimal task phasing that yields the minimal worst-case end-to-end delay. In this study, we propose a heuristic to manage the phase offsets in the distributed tasks to reduce the theoretical end-to-end delay bound. The proposed heuristic reduces the search time for a solution by identifying time intervals where actual communication occurs among inter-dependent tasks. Furthermore, to analyze the distribution of endto- end delays in different phases, we implemented a simulation tool. The simulation results showed that the proposed heuristic can reduce worst-case end-to-end delay as well as jitter in end-to-end delays