Ethernet goes real-time: a survey on research and technological developments

Ethernet is the most popular LAN technology. Its low price and robustness, resulting from its wide acceptance and deployment, has created an eagerness to expand its responsibilities to the factory-floor, where real-time requirements are to be fulfilled. However, it is difficult to build a real-time control network using Ethernet, because its MAC protocol, the 1-persistent CSMA/CD protocol with the BEB collision resolution algorithm, has unpredictable delay characteristics. Many anticipate that the recent technological advances in Ethernet such as the emerging Fast/Gigabit Ethernet, micro-segmentation and full-duplex operation using switches will also enable it to support time-critical applications. This technical report provides a comprehensive look at the unpredictability inherent to Ethernet and at recent technological advances towards real-time operation

Submicron Systems Architecture: Semiannual Technical Report

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On IP over WDM burst-switched long haul and metropolitan area networks

The IP over Wavelength Division Multiplexing (WDM) network is a natural evolution ushered in by the phenomenal advances in networking technologies and technical breakthroughs in optical communications, fueled by the increasing demand in the reduction of operation costs and the network management complexity. The unprecedented bandwidth provisioning capability and the multi-service supportability of the WDM technology, in synergy with the data-oriented internetworking mechanisms, facilitates a common shared infrastructure for the Next Generation Internet (NGJ). While NGI targets to perform packet processing directly on the optical transport layer, a smooth evolution is critical to success. Intense research has been conducted to design the new generation optical networks that retain the advantages of packet-oriented transport prototypes while rendering elastic network resource utilization and graded levels of service. This dissertation is focused on the control architecture, enabling technologies, and performance analysis of the WDM burst-switched long haul and Metropolitan Area Networks (MANs). Theoretical analysis and simulation results are reported to demonstrate the system performance and efficiency of proposed algorithms. A novel transmission mechanism, namely, the Forward Resource Reservation (ERR) mechanism, is proposed to reduce the end-to-end delay for an Optical Burst Switching (OBS)-based IP over WDM system. The ERR scheme adopts a Linear Predictive Filter and an aggressive reservation strategy for data burst length prediction and resource reservation, respectively, and is extended to facilitate Quality of Service (QoS) differentiation at network edges. The ERR scheme improves the real-time communication services for applications with time constraints without deleterious system costs. The aggressive strategy for channel holding time reservations is proposed. Specifically, two algorithms, the success probability-driven (SPD) and the bandwidth usage-driven (BUD) ones, are proposed for resource reservations in the FRRenabled scheme. These algorithms render explicit control on the latency reduction improvement and bandwidth usage efficiency, respectively, both of which are important figures of performance metrics. The optimization issue for the FRR-enabled system is studied based on two disciplines - addressing the static and dynamic models targeting different desired objectives (in terms of algorithm efficiency and system performance), and developing a \u27\u27crank back\u27\u27 based signaling mechanism to provide bandwidth usage efficiency. The proposed mechanisms enable the network nodes to make intelligent usage of the bandwidth resources. In addition, a new control architecture with enhanced address resolution protocol (E-ARP), burst-based transmission, and hop-based wavelength allocation is proposed for Ethernet-supported IP over WDM MANs. It is verified, via theoretical analysis and simulation results, that the E-ARP significantly reduces the call setup latency and the transmission requirements associated with the address probing procedures; the burst-based transport mechanism improves the network throughput and resource utilization; and the hop-based wavelength allocation algorithm provides bandwidth multiplexing with fairness and high scalability. The enhancement of the Ethernet services, in tandem with the innovative mechanisms in the WDM domain, facilitates a flexible and efficient integration, thus making the new generation optical MAN optimized for the scalable, survivable, and IP-dominated network at gigabit speed possible

Performance Improvements for FDDI and CSMA/CD Protocols

The High-Performance Computing Initiative from the White House Office of Science and Technology Policy has defined 20 major challenges in science and engineering which are dependent on the solutions to a number of high-performance computing problems. One of the major areas of focus of this initiative is the development of gigabit rate networks to be used in environments such as the space station or a National Research and Educational Network (NREN). The strategy here is to use existing network designs as building blocks for achieving higher rates, with the ultimate goal being a gigabit rate network. Two strategies which contribute to achieving this goal are examined in detail.1 FDDI2 is a token ring network based on fiber optics capable of a 100 Mbps rate. Both media access (MAC) and physical layer modifications are considered. A method is presented which allows one to determine maximum utilization based on the token-holding timer settings. Simulation results show that employing the second counter-rotating ring in combination with destination removal has a multiplicative effect greater than the effect which either of the factors have individually on performance. Two 100 Mbps rings can handle loads in the range of 400 to 500 Mbps for traffic with a uniform distribution and fixed packet size. Performance is dependent on the number of nodes, improving as the number increases. A wide range of environments are examined to illustrate robustness, and a method of implementation is discussed

Real-Time Estelle

Estelle is one of the standardized Formal Description Techniques for the specification of communication protocols and distributed systems. Unfortunately, Estelle is not capable to express real-time requirements or characteristics of services or protocols which is especially important in the context of distributed multimedia systems. In this paper, we introduce an extension to Estelle called Real-Time Estelle that allows to describe real-time systems. We introduce the syntax of the new language and propose both an operational and a descriptive semantics. Examples show the usefulness of the approach. We also discuss ways to implement Real-Time Estelle specifications

CarRing IV- Real-time Computer Network

Ob in der Automobil-, Avionik- oder Automatisierungstechnik, die Fortschritte in der Echtzeitkommunikation richten sich auf weitere Verbesserungen bereits existierender Lösungen. Im Kfz-Bereich führen die steigenden Zahlen computerbasierter Systeme, Anwendungen und Anschlüsse sowie die Verwendung mehrerer proprietärer Kommunikationsstandards zu einem immer komplexeren Kabelbaum. Ursächlich hierfür sind inkompatible Standards, wodurch nicht nur die Kosten, sondern auch das Gewicht und damit der Kraftstoffverbrauch negativ beeinflusst werden. Im ersten Teil der Dissertation wird das Echtzeitprotokoll von CarRing IV (CRIV) vorgestellt. Es bietet isochrone und harte Echtzeitgarantien, ohne dass eine netzwerkweite Synchronisation erforderlich ist. Mit bis zu 16 Knoten pro Ring kann ein CR-IV-Netz aus bis zu 256 Ringen bestehen, die durch Router miteinander verbunden sind. CR-IV verwendet ein reduziertes OSI-Modell (Schichten 1-3, 7), das für seine Anwendungsbereiche sowohl typisch als auch vorteilhaft ist. Außerdem unterstützt es sowohl ereignis- als auch zeitgesteuerte Kommunikationsparadigmen. Der Transparent-Modus ermöglicht es CR-IV, als Backbone für bestehende Netze zu verwenden, wodurch Inkompatibilitätsprobleme beseitigt werden und der Wechsel zu einer einheitlicheren Netzlösung erleichtert wird. Mit dieser Funktionalität können Nutzergeräte über ein CR-IV-Netz miteinander verbunden werden, ohne dass der Nutzer eingreifen oder etwas ändern muss. Durch Multicast unterstützt CRIV auch die Emulation von Feldbussen. Der zweite Teil der Dissertation stellt den anderen wichtigen Aspekt von CR-IV vor. Alle Schichten des OSI-Modells sind in einem FPGA mit Hardware Description Languages (HDLs) ohne Hard- oder Softprozessoren implementiert. Das Register-Transfer-Level (RTL)-Hardwaredesign von CR-IV wird mit einem neuen Ansatz erstellt, der am besten als tokenbasierter Datenfluss beschrieben werden kann. Der Ansatz ist sowohl vertikal als auch horizontal skalierbar. Er verwendet lose gekoppelte Processing Elements (PEs), die stateless arbeiten, sowie Arbiter/Speicherzuordnungspaare. Durch die granulare Kontrolle und die Aufteilung aller Aspekte einer Lösung eignet sich der Ansatz für die Implementierung anderer Software-Level-Lösungen in Hardware. Viele Testszenarios werden durchgeführt, um die in CR-IV erzielten Ergebnisse zu verdeutlichen und zu überprüfen. Diese Szenarien reichen von direkten Leistungsmessungen bis hin zu verhaltensspezifischen Tests. Zusätzlich wird eine Labor-Demo erstellt, die grundsätzlich auf ein Proof of Concept zielt. Die Demo stellt einen praktischen Test anstelle szenariospezifischer Tests dar. Alle Testszenarien und die Labor-Demo werden mit den Prototyp-Boards des Projekts durchgef¨uhrt, d.h. es sind keine Simulationstests. Die Ergebnisse stellen die realistischen Leistungen von CR-IV mit bis zu 13,61 Gbit/s dar.Whether be it automotive, avionics or automation, advances in their respective real-time communication technology focus on further improving preexisting solutions. For in-vehicle communication, the ever-increasing number of computer-based systems, applications and connections as well as the use of multiple proprietary communication standards results in an increasingly complex wiring harness. This is in-part due to those standards being incompatible with one another. In addition to cost, this also impacts weight, which in turn affects fuel consumption. The work presented in this thesis is in-part theoretical and in-part applied. The former is represented by a new protocol, while the latter corresponds to the protocol’s hardware implementation. In the first part of the thesis, the real-time communication protocol of CarRing IV (CR-IV) is presented. It provides isochronous and hard real-time guarantees without requiring network-wide clock synchronization. With up to 16 nodes per ring, a CR-IV network can consist of as many as 256 rings interconnected by routers. CR-IV uses a reduced OSI model (layers 1-3, 7), which is both typical of and preferable for its application areas. Moreover, it supports both event- and time-triggered communication paradigms. The transparent mode feature allows CR-IV to act as a backbone for existing networks, thereby addressing incompatibility concerns and easing the transition into a more unified network solution. Using this feature, user devices can communicate with one another via a CR-IV network without requiring user interference, or any user device or application changes. Combined with the protocol’s reliable multicast, the feature extends CR-IV’s capabilities to include field bus emulation. The second part of the thesis presents the other important aspect of CR-IV. All of its OSI model layers are implemented in a FPGA using Hardware Description Languages (HDLs) without relying-on or including any hard or soft processors. CR-IV’s Register-Transfer Level (RTL) hardware design is created using a new approach that can best be described as token-based data-flow. The approach is both vertically and horizontally scalable. It uses stateless and loosely coupled Processing Elements (PEs) as well as arbiter/memory allocation pairs. By having granular control and compartmentalizing every aspect of a solution, the approach lends itself to being used for implementing other software-level solutions in hardware. Many test scenarios are conducted to both highlight and examine the results achieved in CR-IV. Those scenarios range from direct performance measurements to behavior-specific tests. Moreover, a lab-demo is created that essentially amounts to a proof of concept. The demo represents a practical test as opposed to a scenariospecific one. Whether be it test scenarios or the lab-demo, all are carried-out using the project’s prototype boards, i.e. no simulation tests. The results obtained represent CR-IV’s real-world realistic outcomes with up to 13.61 Gbps