Burst switched optical networks supporting legacy and future service types

Focusing on the principles and the paradigm of OBS an overview addressing expectable performance and application issues is presented. Proposals on OBS were published over a decade and the presented techniques spread into many directions. The paper comprises discussions of several challenges that OBS meets, in order to compile the big picture. The OBS principle is presented unrestricted to individual proposals and trends. Merits are openly discussed, considering basic teletraffic theory and common traffic characterisation. A more generic OBS paradigm than usual is impartially discussed and found capable to overcome shortcomings of recent proposals. In conclusion, an OBS that offers different connection types may support most client demands within a sole optical network layer

Integration of quantum key distribution in metropolitan area networks

The deployment of Quantum Key Distribution forces the development of QKD-links to be operated in current and next-generation photonic metro-access networks. These highly heterogeneous architectures determine the conditions QKD-links need to be optimized for

ICT BONE views on the network of the future: the role of optical networking

Part of the activities of the ICT EU Network of Excellence “Building the future Optical Network in Europe” (BONE) project is the development of the European Roadmap on Optical Networking in the context of the “Network of the Future”. This paper presents a summary of the views of the BONE consortium as they were developed in the framework of the Roadmap activity. The methodology followed in the development of the BONE Roadmap was firstly to identify and analyse the status of broadband access penetration as well as the availability of specific network and IT technologies in various European countries. The data collected were then processed and translated into the traffic volume (distributed across different European countries) that a Pan- European network would need to support. This information is then used as the basis of a WDM optical network dimensioning exercise performed with the aim of identifying the scale of the required optical network. In addition, based on estimations regarding the evolution of broadband access technologies and the degree of broadband penetration and network services and applications, extrapolations regarding the growth of traffic to be supported by the European Network of the Future were made in a systematic manner. These were also used to dimension and understand the requirements of the European Network of the Future. This paper presents the relevant results and also provides a discussion on the BONE consortium views on the Network of the Future from an architectural and technology perspective and an outlook of the relevant key research challenges and possible solutions.Postprint (published version

Queueing models for multi-service networks

Zsfassung in dt. SpracheDie Doktorarbeit beginnt in Kapitel 1 mit grundlegenden Beobachtungen und einer Zusammenfassung der statistischen Methoden die üblicherweise zur Bestimmung der Leistungsfähigkeit eines Kommunikationsnetzes Verwendung finden. Vielfachprotokollmarkierungsumschaltung (MPLS) wird vorgestellt und im weiteren als Beispiel für die Effizienzbewertung von Netzkomponenten unter Berücksichtigung mehrerer Datenflüsse verwendet. In Kapitel 2 werden erst grundlegende Wahrscheinlichkeitsverteilungsfunktionen vorgestellt welche zur Modellierung der Zwischenankunftszeiten und Bedienzeiten Verwendung finden. Im weiteren werden Methoden zur Modellierung komplexerer Prozesse durch die Verknüpfung einzelner negaitv exponentieller Phasen zu mathematisch handhabbaren Markovketten gezeigt. Darauf basierend werden in Kapitel 3 grundlegende Warteschlangensysteme vorgestellt, wie sie auch in den meisten Lehrbüchern zu finden sind, wohl aber kaum in einer identischen Zusammenstellung. Beginnend mit unendlichen Warteschlangensystemen mit mehreren Verarbeitungsinstanzen werden im weiteren praxisgerechte endliche und warteschlangenlose Systems behandelt. In diesem Zusammenhang lernen wir verschiedene Möglichkeiten kennen wie derartige Systeme mithilfe von Markovketten analysiert werden können, also auch andere Methoden für Systeme die sich mittels Markovketten nicht modellieren lassen. Schließlich, in Kapitel 4, werden die vorgestellten Konzepte und Methoden dazu verwendet die primären Mechanismen von Kommunikationsnetzknoten mit Dienstklassendifferenzierung zu untersuchen. Angefangen bei der gemeinsamen Nutzung der zur Verfügung stehenden Transportkapazitäten und der Flusspriorisierung kommen wir im weiteren zur Datenstauabarbeitung und schließlich zu verketteten und vernetzten Warteschlangensystemen. Zu guter letzt, in Kapitel 4.4, wird eine subjektive Vision zukünftiger Netzverwaltungskonzepte umrissen, basierend auf der Beobachtung, dass Überlast der Hauptgrund für eine Dienstverschlechterung darstellt sowie der intuitiven Erkenntnis, dass dieses Hindernis nicht ohne eine gute Netzverwaltung ausgemerzt werden kann. Es wird davon ausgegangen, dass das grundlegende Problem der zeitnahen Bereitstellung von Datenverbindungen mittels vor-konfektionierter Verbindungsstücke und der Anpreisung der damit bereitstellbaren Ende-zu-Ende Dienstqualitäten gelöst werden kann. Das Lastausbalanzierungsproblem wird hier nicht bis ins Detail gelöst da eine seriöse Darstellung des Wegefindungsproblemes, wie es nötig ist um Lastgleichverteilung zu erreichen, zumindest ein weiteres umfangreiches Kapitel bedürfen würde. Basierend auf früheren Arbeiten wird davon ausgegangen, dass die Einführung einer virtuellen Netzebene das Skalierungsproblem löst, und dass die Verwendung fähiger Algorithmen, wie zum Beispiel dem Verbleibende Netz- und Link-Kapazität basierten Algorithmus (RNLC), innerhalb der begrenzten Netzbereiche mit vertretbarem Rechenaufwand möglich ist. Kapitel 5 beschließt die Dissertation und wirft einen Blick zurück auf die Vorbereitung sowie die identifizierten Erkenntnisse und Hindernisse. In den Ergänzungen finden sich Beispiele der Octave Programme die im Verlauf der Arbeit entstanden und Verwendung fanden zur Berechnung der vielen Systemqualitätskurven. Insbesondere sind das die ereignisgesteuerte Simulation und ein Beispiel für den Matrizen basierten Entwurf von mehrdimensionalen Zustandsübergangsdiagrammen.The thesis starts in chapter 1 with basic observations and a survey of statistical methods commonly used to express the performance of communication network components and other systems based on stochastic processes. Multi Protocol Label Switching (MPLS) is introduced and further on used as example toward a modern multi-flow based network performance assessment. In chapter 2 we first introduce some basic distributions to model the inter-arrival and holding time distributions, and second, we present methods to construct or approximate more complex processes by mathematically tractable Markov chains. Based thereon we then exemplify basic queueing models in chapter 3, as they can be found in most text-books on queueing theory, though hardly in a similar synopsis. Starting with infinite multi-server systems we continue to the more practical finite and queue-less systems, and learn about different approaches to analyse these systems based on the Markov chains that result from the state transition diagrams representing these systems in a comprehensible manner, besides other methods applied where Markov chains are not an option. Finally, in chapter 4 we use the introduced concepts and methods to evaluate the principal mechanisms of multi-service communication network components. Form resource sharing and flow prioritisation we proceed to congestion mitigation and finally chains and networks of queueing systems. In the end, in section 4.4, we outline a subjective vision of future network management concepts based on the observation that the main cause for service degradation is overload, and the intuitive conclusion that this obstacle cannot be mitigated without proper network management. The basic instantaneous connectivity demand problem is assumed to be solved by connection advertisement based on pre-configured intra section paths and pre-calculated expectable service quality for the advertised end-to-end paths. The load balancing issue is not solved in detail because a reasonable discussion of the routing topic, required to achieve load balancing, would add at least one more lengthy chapter. Instead, based on previous work, it is assumed that the introduction of a common virtual network level in the management hierarchy solves the scalability problem and that per autonomous network section capable algorithms alike the Residual Network and Link Capacity algorithm can be applied with reasonable computation effort. Chapter 5 concludes the thesis, reflecting on the course of preparing the thesis and the findings and obstacles identified. The addenda provide examples of the Octave programs used to calculate the many figures on system performance metrics, in particular the event based system simulation routine and an example on the matrix oriented design of multidimensional state transition diagrams.32

Interdependence of dynamic traffic flows

End-to-end (e2e) quality of service (QoS) is the key target to be achieved in order to successfully support high quality real-time services. While ISDN, SDH and ATM provide service classes that natively support constant bit-rate transmission tunnels, i.e. provide circuit switching that offers constant bandwidth for the entire duration of a service, packet switched technologies natively do not provide that option. The economically irreversible migration to the Internet protocol (IP) as transport plane for all kinds of services necessitates sophisticated traffic engineering to fulfil the basic service demands of real-time services being low latency, fast round-trip times (RTT), negligible jitter and minimal loss-rate. Most of the current approaches to optimise IP routing for real-time services target firstly at admission control and secondly on node internal priority scheduling. In this study we focus on the second part and try to evaluate the problems that arise when such node internal mechanisms get cascaded along a path, i.e. study the problems that need to be solved in order to derive e2e QoS from node performance in dynamic network scenarios. From the results mechanisms for dynamic admission control and priority scheduling in relation to current network and node state could be derived

Technical Framework on Local Energy Communities (TF-LEC) Vol.1 Version 0.5 - First trial release

Vol.1 of the Technical Framework on Local Energy Communities (TF-LEC) summarises and clarifies the Local Energy Communities Business Case considered henceforth, including environmental constraints and envisioned opportunities to integrate energy consumers and distributed energy resources (DER) in the short term balancing of energy supply and demand. According to the IES (Integrating the Energy System – www.iesaustria.at) recommendations and templates, any Technical Framework is a structured compilation of informative and normative specifications. The Vol.1 is informative, includes the specification of operational functionalities (Business Functions) and the naming of the independent IT systems that interact (Meta-Actors). Common approaches, technologies, standards, good practice, and alike is briefly introduced.Österreichische Forschungsförderungsgesellschaft mbH (FFG)7

Situation Awareness by Simple Intuitive Traffic Light Signals for Smart Utilisation of Local Demand and Supply Flexibility

To realise the energy transition, every renewable source shall at least partially contribute to the demand–supply balancing, including customer-owned controllable loads and energy sources. Their commonly small size and spatial occurrence suggests addressing volatility issues locally, using local flexibilities to mitigate their impact. This calls for simple and effective signalling that enables interaction among local stakeholders, including local producers and customers. According interfaces and information formats appear to not yet exist. In this article, we propose a traffic-light-like system that enables the local grid operator to trigger situation-aware customer behaviour, supporting grid stability when needed and, in return, allowing customers to fully exploit temporary grid capacity when no safety or stability issues persist. The applied intuitive deduction method based on existing coordination mechanisms and objectives indicates, without proof, that the proposed granular traffic light system can enable the distribution grid flexibility required to facilitate more renewable energy being produced and inserted by local customers, to relieve grid levels above from transporting and equalising volatile energy shares, and to improve the economics of distributed renewable energy sources

Situation Awareness by Simple Intuitive Traffic Light Signals for Smart Utilisation of Local Demand and Supply Flexibility

To realise the energy transition, every renewable source shall at least partially contribute to the demand–supply balancing, including customer-owned controllable loads and energy sources. Their commonly small size and spatial occurrence suggests addressing volatility issues locally, using local flexibilities to mitigate their impact. This calls for simple and effective signalling that enables interaction among local stakeholders, including local producers and customers. According interfaces and information formats appear to not yet exist. In this article, we propose a traffic-light-like system that enables the local grid operator to trigger situation-aware customer behaviour, supporting grid stability when needed and, in return, allowing customers to fully exploit temporary grid capacity when no safety or stability issues persist. The applied intuitive deduction method based on existing coordination mechanisms and objectives indicates, without proof, that the proposed granular traffic light system can enable the distribution grid flexibility required to facilitate more renewable energy being produced and inserted by local customers, to relieve grid levels above from transporting and equalising volatile energy shares, and to improve the economics of distributed renewable energy sources

From Integration Profiles to Interoperability Testing for Smart Energy Systems at Connectathon Energy

The project Integrating the Energy System (IES) Austria recognises interoperability as key enabler for the deployment of smart energy systems. Interoperability is covered in the Strategic Energy Technology Plan (SET-Plan) activity A4-IA0-5 and provides an added value because it enables new business options for most stakeholders. The communication of smart energy components and systems shall be interoperable to enable smooth data exchange, and thereby, the on demand integration of heterogeneous systems, components and services. The approach developed and proposed by IES, adopts the holistic methodology from the consortium Integrating the Healthcare Enterprise (IHE), established by information technology (IT) vendors in the health sector and standardised in the draft technical report ISO DTR 28380-1, to foster interoperable smart energy systems. The paper outlines the adopted IES workflow in detail and reports on lesson learnt when trial Integration Profiles based on IEC 61850 were tested at the first Connectathon Energy instalment, organised in conjunction with the IHE Connectathon Europe 2018. The IES methodology is found perfectly applicable for smart energy systems and successfully enables peer-to-peer interoperability testing among vendors. The public specification of required Integration Profiles, to be tested at subsequent Connectathon Energy events, is encouraged