Comparing Admission Control Architectures for Real-Time Ethernet

Industry 4.0 and Autonomous Driving are emerging resource-intensive distributed application domains that deal with open and evolving environments. These systems are subject to stringent resource, timing, and other non-functional constraints, as well as frequent reconfiguration. Thus, real-time behavior must not preclude operational flexibility. This combination is motivating ongoing efforts within the Time Sensitive Networking (TSN) standardization committee to define admission control mechanisms for Ethernet. Existing mechanisms in TSN, like those of AVB, its predecessor, follow a distributed architecture that favors scalability. Conversely, the new mechanisms envisaged for TSN (IEEE 802.1Qcc) follow a (partially) centralized architecture, favoring short reconfiguration latency. This paper shows the first quantitative comparison between distributed and centralized admission control architectures concerning reconfiguration latency. Here, we compare AVB against a dynamic real-time reconfigurable Ethernet technology with centralized management, namely HaRTES. Our experiments show a significantly lower latency using the centralized architecture. We also observe the dependence of the distributed architecture in the end nodes' performance and the benefit of having a protected channel for the admission control transactions.This work was supported in part by the Spanish Agencia Estatal de Investigación (AEI), in part by the Fondo Europeo de Desarrollo Regional (FEDER) [AEI/FEDER, Unión Europea (UE)] under Grant TEC2015-70313-R, in part by the European Regional Development Fund (FEDER) through the Operational Programme for Competitivity and the Internationalization of Portugal 2020 Partnership Agreement (PRODUTECH-SIF) under Grant POCI-01-0247-FEDER-024541, and in part by the Research Centre Instituto de Telecomunicações under Grant UID/EEA/50008/2013.info:eu-repo/semantics/publishedVersio

Modelação e simulação de equipamentos de rede para Indústria 4.0

Currently, the industrial sector has increasingly opted for digital technologies in order to automate all its processes. This development comes from notions like Industry 4.0 that redefines the way these systems are designed. Structurally, all the components of these systems are connected in a complex network known as the Industrial Internet of Things. Certain requirements arise from this concept regarding industrial communication networks. Among them, the need to ensure real-time communications, as well as support for dynamic resource management, are extremely relevant. Several research lines pursued to develop network technologies capable of meeting such requirements. One of these protocols is the Hard Real-Time Ethernet Switch (HaRTES), an Ethernet switch with support for real-time communications and dynamic resource management, requirements imposed by Industry 4.0. The process of designing and implementing industrial networks can, however, be quite time consuming and costly. These aspects impose limitations on testing large networks, whose level of complexity is higher and requires the usage of more hardware. The utilization of network simulators stems from the necessity to overcome such restrictions and provide tools to facilitate the development of new protocols and evaluation of communications networks. In the scope of this dissertation a HaRTES switch model was developed in the OMNeT++ simulation environment. In order to demonstrate a solution that can be employed in industrial real-time networks, this dissertation presents the fundamental aspects of the implemented model as well as a set of experiments that compare it with an existing laboratory prototype, with the objective of validating its implementation.Atualmente o setor industrial tem vindo cada vez mais a optar por tecnologias digitais de forma a automatizar todos os seus processos. Este desenvolvimento surge de noções como Indústria 4.0, que redefine o modo de como estes sistemas são projetados. Estruturalmente, todos os componentes destes sistemas encontram-se conectados numa rede complexa conhecida como Internet Industrial das Coisas. Certos requisitos advêm deste conceito, no que toca às redes de comunicação industriais, entre os quais se destacam a necessidade de garantir comunicações tempo-real bem como suporte a uma gestão dinâmica dos recursos, os quais são de extrema importância. Várias linhas de investigação procuraram desenvolver tecnologias de rede capazes de satisfazer tais exigências. Uma destas soluções é o "Hard Real-Time Ethernet Switch" (HaRTES), um switch Ethernet com suporte a comunicações de tempo-real e gestão dinâmica de Qualidade-de-Serviço (QoS), requisitos impostos pela Indústria 4.0. O processo de projeto e implementação de redes industriais pode, no entanto, ser bastante moroso e dispendioso. Tais aspetos impõem limitações no teste de redes de largas dimensões, cujo nível de complexidade é mais elevado e requer o uso de mais hardware. Os simuladores de redes permitem atenuar o impacto de tais limitações, disponibilizando ferramentas que facilitam o desenvolvimento de novos protocolos e a avaliação de redes de comunicações. No âmbito desta dissertação desenvolveu-se um modelo do switch HaRTES no ambiente de simulação OMNeT++. Com um objetivo de demonstrar uma solução que possa ser utilizada em redes de tempo-real industriais, esta dissertação apresenta os aspetos fundamentais do modelo implementado bem como um conjunto de experiências que o comparam com um protótipo laboratorial já existente, no âmbito da sua validação.Mestrado em Engenharia Eletrónica e Telecomunicaçõe

A Real-Time Software Defined Networking Framework for Next-Generation Industrial Networks

Industry 4.0 brings in a whole set of new requirements to engineering industrial systems, with notorious impact at the networking layer. A key challenge posed by Industry 4.0 is the operational flexibility needed to support on-the-fly reconfiguration of production cells, stations, and machines. At the networking layer, this flexibility implies dynamic packet handling, scheduling, and dispatching. SoftwareDefined Networking (SDN) provides this level of flexibility in the general Local Area Network (LAN) domain. However, its application in the industry has been hindered by a lack of support for real-time services. This paper addresses this limitation, proposing an extended SDN OpenFlow framework that includes realtime services, leveraging existing real-time data plane Ethernet technologies. We show the OpenFlow enhancements, a real-time SDN controller, and experimental validation and performance assessment. Using a proof-of-concept prototype with 3 switches and cycles of 250µs, we could achieve 1µs jitter on timetriggered traffic and a reconfiguration time between operational modes below 10msinfo:eu-repo/semantics/publishedVersio

Wieloplatformowy system zarządzania przełącznikiem Ethernetowym czasu rzeczwistego

Mestrado em Engenharia Electrónica e TelecomunicaçõesAo longo dos últimos anos, o agora onipresente protocolo Ethernet, embora não dotado de mecanismos eficazes de gestão de QoS, foi ganhando uma grande aceitação no campo das comunicações industriais. Esta crescente aceitação deveu-se, em grande parte, a novos protocolos, baseados em Ethernet (por exemplo, Profinet, Ethernet Industrial, etc), capazes de fornecer comunicações com garantias deterministas ou de tempo-real. O comutador Ethernet Hartes (Hard Real-Time Ethernet Switch), foi desenvolvido para disponibilizar uma infra-estrutura de comutação Ethernet capaz de fornecer garantias de pontualidade, de bom uso da largura de banda e para suportar, de modo eficiente, a flexibilidade operacional necessária em aplicações de tempo-real distribuídas, de sistemas embarcados dinâmicos. O desenvolvimento do comutador Hartes, foi baseado em trabalho anterior do paradigma de comunicação FTT (Flexible Time-Triggered), e teve por objetivo o projeto de um comutador Ethernet com melhor controlo de transmissão, escalonamento do tráfego e integração transparente de nodos não tempo-real. NetConf é uma tecnologia recente de gestão de redes que tem vindo progressivamente a substituir a tecnologia SNMP (Simple Network Management Protocol), o standard de facto há muito adoptado pela indústria. A maior diferença entre NetConf e o SNMP é que o NetConf adopta um mecanismo de comunicação baseado em XML-RPC, que, graças às ferramentas desenvolvidas no âmbito de outras tecnologias web, permite ciclos mais rápidos e mais simples de desenvolvimento e de gestão. O comutador Hartes não dispõe de uma plataforma de gestão com uma interface padronizada para os protocolos SNMP ou NetConf, de modo a permitir a sua gestão remota. Assim, o objetivo principal deste trabalho é o desenvolvimento de componentes-chave de apoio à gestão multiplataforma do comutador Ethernet Hartes, bem como a respectiva avaliação de desempenho dos componentes desenvolvidos.In recent years, the now ubiquitous Ethernet protocol that lacks effective QoS management functions, has gained momentum in the field of industrial communication, by means of novel, Ethernet-based protocols (e.g. Profinet, Industrial Ethernet, etc.), which are able to provide deterministic communications. HaRTES – Hard Real-Time Ethernet Switch, aimed to develop an Ethernet switching infrastructure, able to provide timeliness guarantees, efficient bandwidth usage and support for operational flexibility as required by dynamic real-time distributed embedded systems. The project was built upon previous work on the FTT (Flexible Time-Triggered) communication paradigm to develop Ethernet switches with enhanced transmission control, traffic scheduling, and transparent integration of non-real-time nodes. NetConf is a recent network management technology that is replacing the Simple Network Management Protocol (SNMP) – widely used and long adopted by industry standard. The biggest difference between NetConf and SNMP is that the former use a communication mechanism based on XML-RPC, which, thanks to the tools developed in the scope of other web technologies, allows a simpler and faster development and management cycle. The HaRTES project had not provided a management platform with a standardized interface for SNMP or NetConf protocols, enabling remote switch management. Thus the main objective of this work was to develop key components for the support of the standardized multiplatform management interfaces for the HaRTES switch and their performance assessment

Suporte MSRP para Hard Qds Switch

Mestrado em Engenharia Electrónica e TelecomunicaçõesA exigência de comunicações de Tempo-Real em processos industriais e sistemas embutidos distribuídos foi, durante muitos anos, satisfeita com recurso a redes de campo especializadas (comummente designadas por fieldbuses). Contudo, a crescente utilização de redes Ethernet, aliada a vantagens competitivas a elas inerentes como o preço e velocidade, levou a que se procurassem soluções que permitissem utilizar esta tecnologia em ambientes de Tempo-Real. Apesar de algumas limitações evidenciadas, como o indeterminismo temporal que o seu funcionamento apresenta, diversos protocolos surgiram nos últimos anos no sentido de adaptar o seu funcionamento aos requisitos das comunicações de Tempo-Real. Contudo, os protocolos que foram sendo apresentados são maioritariamente estáticos e off-line, não possibilitando uma gestão dinâmica da Qualidade de Serviço. Assim, surgiu na Universidade Aveiro um switch, o HaRTES (Hard Real-Time Ethernet Switch), capaz de fornecer garantias de Tempo-Real com uma maior flexibilidade na gestão de recursos. Adicionalmente, o fornecimento de garantias de Qualidade de Serviço pressupõe a existência de reserva de recursos nas estações de uma rede. Para que isso seja possível, foram propostos alguns protocolos de sinalização como o Resource Reservation Protocol (RSVP) e o Stream Reservation Protocol (SRP). O HaRTES, não obstante o facto de garantir Qualidade de Serviço de uma forma dinâmica, não suporta nenhum protocolo normalizado no mercado. Consequentemente, surgiu a necessidade de desenvolver uma plataforma que permita ao referido switch suportar a reserva de recursos recorrendo a um desses protocolos. Devido a um mais fácil mapeamento de parâmetros, foi escolhido o SRP. Este trabalho apresenta-o de uma forma detalhada, discute os blocos estruturais essenciais à sua implementação, detalha o seu fun-cionamento e pormenoriza as mensagens trocadas entres os diversos intervenientes. A implementação de alguns dos blocos é discutida no âmbito desta dissertação e alguns testes funcionais descritos. Estes permitiram vali-dar o trabalho desenvolvido, abrindo a oportunidade de se integrar por completo o protocolo de sinalização SRP no switch HaRTES.For several years, the hard demands of real-time communications in industrial processes and embedded systems, has been solve with the use of specialized fieldbuses. However, due to the increasing usage of Ethernet networks, together with its inherent competitive advantages like reduced price and fast velocities, a search for new solutions that allow the use of these networks in Real-Time environments began. Despite of its limitations, such as temporal indeterminism derived from its medium access control scheme, many protocols have been developed in the last few years with the objective of adapting its functionalities to the requirements of Real-Time communications. Nevertheless, mostly of the protocols developed are static and based on pre-runtime analysis. As a consequence, they don’t allow a dynamic management of the Quality of Service (QoS). Thus, it was constructed at Aveiro University a new modified switch, HaRTES (Hard Real-Time Ethernet Switch), capable of providing Real-Time guarantees with greater resource management flexibility. Furthermore, providing guaranteed Quality of Service requires the existence of resource reservation along the nodes of a network. In order to make this possible some signalling protocols were proposed, such as the Resource Reservation Protocol (RSVP) and Stream Reservation Protocol (SRP). Even if the HaRTES switch guarantees Quality of Service in a dynamic way, it doesn’t support any protocol standard. Therefore, the need of developing a new platform that will enable the switch to perform resource reservations using standard protocols emerged. Due to the easier mapping of parameters, the SRP was chosen to be that platform. This work describes it in detail. It discusses the structural blocks crucial for its implementation, describes the protocol operation and details the messages exchanged between the different nodes in a network. The implementation of some blocks is discussed and some tests are performed allowing the validation of the work developed. The results of this work open a window opportunity for the total integration of the SRP protocol in the HaRTES switch

Dynamic Quality-of-Service Management Under Software-Defined Networking Architectures

The Internet is facing new challenges emerging from new trends in Information and Communication Technologies (ICT) for example, cloud services, Big Data, increased mobile usage etc. Traditional IP networks rely in two design principles that, despite serving as an effective solution in the last decades, have become deprecated and not well fit for the new challenges. First, the control and data plane are tightly embedded in the networking devices and second, the structure is highly decentralized with no centralized point of management. This static and rigid architecture leaves no space for innovation with a consequence lack of scalability. Also, it leads to high management and operation costs. The SDN paradigm provides a more dynamic, manageable, cost-effective and adaptable architecture that is ready for the dynamic nature of today's applications. The goal of this thesis is a novel SDN-enabled solution that provides dynamic Quality of Service management for real-time and multimedia applications. This solution will be tested and implemented over a real, not-simulated testbed, composed by OpenFlow-enabled devices, the ONOS SDN controller and client terminals that produced/consume data streams. Furthermore, it is also expected to characterize and evaluate the benefits of the SDN-based solution against a traditional usage of the network (non-SDN)

Controlo distribuído de um braço robótico

Mestrado em Engenharia Electrónica e TelecomunicaçõesMuitos dos sistemas electr´onicos de hoje em dia necessitam de executar tarefas com determinados requisitos de pontualidade, previsibilidade ou rela¸c˜oes de precedˆencia. O cumprimento destes leva muitas vezes `a necessidade de utiliza¸c˜ao de sistemas operativos de tempo-real (RTOS), devidamente complementados por redes de tempo-real, no caso de sistemas distribu´ıdos. No ˆambito desta disserta¸c˜ao desenvolveram-se estruturas b´asicas para um demonstrador do protocolo FTT-SE, que oferece comunica¸c˜ao tempo-real sobre Ethernet. Este demonstrador ´e baseado num bra¸co rob´otico com cinco graus de liberdade, o que corresponde a cinco juntas ou eixos, estando cada uma destas ligada a um computador que a controla. Foram desenvolvidos device drivers para o RTOS RTLinux para efectuar a comunica¸c˜ao com o hardware desenvolvido que permite obter informa¸c˜ao sobre a posi¸c˜ao da junta do bra¸co rob´otico bem como controlar o movimento do motor. Foram desenvolvidos tamb´em algoritmos de controlo e cinem´atica com o objectivo de controlar o movimento de cada junta do bra¸co de forma a que esta siga uma traject´oria previamente definida.Many of the electronic systems of today need to perform tasks with certain requirements of timeliness, predictability or precedence relations. The fulfilment of this requirements often leads to the need to use real-time operating systems (RTOS), fully complemented by real-time networks, in case of distributed systems. In this dissertation it was developed basic structures for a FTT-SE protocol demonstrator, which provides real-time communication over Ethernet. This demonstrator is based on a robotic arm with five degrees of freedom, corresponding to five joints or axes, with each one of these connected to a computer that controls it. We developed device drivers for the RTOS RTLinux to allow the communication with the hardware developed that provides the joint position of the robotic arm and control the movement of its engine. In addition, kinematics and control algorithms were developed in order to control the movement of each joint of the arm so that it follows a predefined trajectory

The Virtual Bus: A Network Architecture Designed to Support Modular-Redundant Distributed Periodic Real-Time Control Systems

The Virtual Bus network architecture uses physical layer switching and a combination of space- and time-division multiplexing to link segments of a partial mesh network together on schedule to temporarily form contention-free multi-hop, multi-drop simplex signalling paths, or 'virtual buses'. Network resources are scheduled and routed by a dynamic distributed resource allocation mechanism with self-forming and self-healing characteristics. Multiple virtual buses can coexist simultaneously in a single network, as the resources allocated to each bus are orthogonal in either space or time. The Virtual Bus architecture achieves deterministic delivery times for time-sensitive traffic over multi-hop partial mesh networks by employing true line-speed switching; delays of around 15ns at each switching point are demonstrated experimentally, and further reductions in switching delays are shown to be achievable. Virtual buses are inherently multicast, with delivery skew across multiple destinations proportional to the difference in equivalent physical length to each destination. The Virtual Bus architecture is not a purely theoretical concept; a small research platform has been constructed for development, testing and demonstration purposes