In network design, the gap between theory and practice is woefully broad. This book narrows it, comprehensively and critically examining current network design models and methods. You will learn where mathematical modeling and algorithmic optimization have been under-utilized. At the opposite extreme, you will learn where they tend to fail to contribute to the twin goals of network efficiency and cost-savings. Most of all, you will learn precisely how to tailor theoretical models to make them as useful as possible in practice. Throughout, the authors focus on the traffic demands encountered in the real world of network design. Their generic approach, however, allows problem formulations and solutions to be applied across the board to virtually any type of backbone communication or computer network. For beginners, this book is an excellent introduction. For seasoned professionals, it provides immediate solutions and a strong foundation for further advances in the use of mathematical modeling for network design. (Less)

Routing, Flow, And Capacity Design In Communication And Computer Networks

This article describes the Survivable Network Design Library (SNDlib), a data library for fixed telecommunication network design available at . In the current version 1.0, the library contains data related to 22 networks which, combined with a set of selected planning parameters, leads to 830 network design problem instances. In this article, we discuss the data concepts of SNDlib and describe a mathematical model for each design problem considered in the library. We also provide information on characteristic features and the origin of the SNDlib problem instances. © 2009 Wiley Periodicals, Inc. NETWORKS, 2010

/pdf/sndlib-1-0-survivable-network-design-library-20x8gxsidg.pdf

SNDlib 1.0—Survivable Network Design Library

This article describes the Survivable Network Design Library (SNDlib), a data library for fixed telecommunication network design available at http://sndlib. zib.de. In the current version 1.0, the library contains data related to 22 networks which, combined with a set of selected planning parameters, leads to 830 network design problem instances. In this article, we discuss the data concepts of SNDlib and describe a mathematical model for each design problem considered in the library. We also provide information on characteristic features and the origin of the SNDIib problem instances.

SNDlib 1.0 - survivable network design library

The traffic to be carried by today's European backbone networks increases very rapidly. An important portion of this traffic consists of data traffic (mainly IP-related). In the future data traffic is expected to become the abundantly dominant traffic type, while voice traffic will only account for a very small portion of the total traffic volume. In this paper, some network topologies for such a pan-European fiber-optic backbone network are presented (more details can be found in [1]). These topologies are compared in terms of the efficiency of the network design both from a cost and capacity point of view and in terms of the availability of the connections routed over this network. In order to be able to assess the network topologies under realistic circumstances, the expected traffic demand is forecasted. This enables to make the comparison for the current traffic volume as well as for the traffic patterns of the future. As not all types of (data) traffic require the same degree of survivability and in order to leverage the total capacity cost of the network design, a distinction is made between different recovery options in the optical layer for the different traffic types considered.

Pan-European optical transport networks: An availability-based comparison

Over the past 25 years, networks have evolved from being relatively static with fairly homogeneous traffic to being more configurable and carrying a heterogeneous array of services. As the applications are ultimately the driver of network evolution, the paper begins with a brief history of circuit, packet, and wave services, along with the development of the corresponding transport layers. The discussion then moves to the evolution of network-node architecture, with an emphasis on the optical-electrical-optical and optical-bypass paradigms. Scalability and cost-effectiveness in meeting network demands are two key factors in the discussion. The evolution of networking equipment, along with the development of the optical control plane, has facilitated a configurable optical layer. The enabling technologies, along with their ramifications, are discussed. Finally, the paper speculates on how capacity might evolve in the future, to handle the undoubtedly new services that are on the horizon.

http://www.monarchna.com/OpticalNetworking25Years-JLT-AnnivIssue-w.pdf

Optical Networking: Past, Present, and Future

The explosive growth of data traffic-for example, due to the popularity of the Internet-poses important emerging network requirements on today's telecommunication networks. This paper describes how core networks will evolve to optical transport networks (OTNs), which are optimized for the transport of data traffic, resulting in an IP-directly-over-OTN paradigm. Special attention is paid to the survivability of such data-centric optical networks. This becomes increasingly crucial since more and more traffic is multiplexed onto a single fiber (e.g., 160/spl times/10 Gb/s), implying that a single cable cut can affect incredible large traffic volumes. In particular, this paper is tackling multilayer survivability problems, since a data-centric optical network consists of at least an IP and optical layer. In practice, this means that the questions "in which layer or layers should survivability be provided?" and "if multiple layers are chosen for this purpose, then how should this functionality in these layers be coordinated?" have to be answered. In addition to a theoretical study, some case studies are presented in order to illustrate the relevance of the described issues and to help in strategic planning decisions. Two case studies are studying the problem from a capacity viewpoint. Another case study presents simulations from a timing/throughput performance viewpoint.

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Data-centric optical networks and their survivability

Aims
To report the impact of transformational leadership on two dimensions of nurses' safety performance (i.e. safety compliance and safety participation) and to study the mediating role of knowledge-related job characteristics in this relationship.

Background
Safety performance refers to the behaviours that employees exhibit to adhere to safety guidelines and to promote health and safety at their workplace. Nurses' safety performance is a major challenge for healthcare settings, urging the need to identify the key determinants and psychological mechanisms that influence it.

Design
A cross-sectional survey study.

Methods
The study was carried out in September 2010 in a large Belgian hospital. We used self-administered questionnaires; 152 nurses participated. The hypotheses were tested using hierarchical regression analyses.

Results/Findings
In line with our first hypothesis, the results show that transformational leadership exerted a significant positive impact on both dimensions of nurses' safety performance. This positive relation was mediated by knowledge-related job characteristics, supporting our second hypothesis.

Conclusion
Head nurses' transformational leadership can enhance nurses' compliance with and participation in safety. Furthermore, transformational head nurses are able to influence the perception that their nurses have about the kind and amount of knowledge in their job, which can also lead to increases in both dimensions of nurses' safety performance. This study therefore demonstrates the key impact that transformational head nurses have, both directly and indirectly, on the safety performance of their nurses.

Transformational leadership and safety performance among nurses: the mediating role of knowledge-related job characteristics

The integration of different network technologies into a multilayer network, as in Internet-based networks carried by optical transport networks (OTNs), creates new opportunities but also challenges with respect to network survivability In different network layers, recovery mechanisms that are active can be exploited jointly to reach a more efficient or faster recovery from failures This interworking is also indispensable in order to overcome the variety of failure scenarios that can occur in the multilayer-network environment A well-considered coordination between the different layers and their recovery mechanisms is crucial in order to attain high performance recovery This paper provides an overview of multilayer recovery issues and solutions in an Internet protocol (IP)-over-optical-network environment, which is illustrated by quantitative case studies

https://biblio.ugent.be/publication/350923/file/455677.pdf

Recovery in multilayer optical networks

Intelligent Optical Networks (IONs) allow setting up or tearing down lightpaths dynamically. The logical topology in multi-layer networks (such as IP-over-OTN scenarios) is supported by these lightpaths, and thus dynamically configurable. Consequently, traffic engineering functionality is extended with cross-layer capabilities, leading to multi-layer traffic engineering (MTE). This paper explains the concepts behind MTE, how typical MTE strategies function and what issues arise while developing such strategies. The benefits are illustrated by means of the results from two case studies.

Ilse Lievens

Papers

Pan-European optical transport networks: An availability-based comparison

Data-centric optical networks and their survivability

Transformational leadership and safety performance among nurses: the mediating role of knowledge-related job characteristics

Recovery in multilayer optical networks

Multi-layer traffic engineering in data-centric optical networks - illustration of concepts and benefits (IST LION)