Reliability issues in network planning

One of the main focuses for network planning is on the optimization of network resources required to build a network under certain traffic demand projection. Traditionally, the inputs to this type of network planning problems are treated as deterministic. In reality, the varying traffic requirements and fluctuations in network resources can cause uncertainties in the decision models. The failure to include the uncertainties in the network design process can severely affect the feasibility and economics of the network. Therefore, it is essential to find a solution that can be insensitive to the uncertain conditions during the network planning process. As early as in the 1960's, a network planning problem with varying traffic requirements over time had been studied. Up to now, this kind of network planning problems is still being active researched, especially for the VPN network design. Another kind of network planning problems under uncertainties that has been studied actively in the past decade addresses the fluctuations in network resources. One such hotly pursued research topic is survivable network planning. It considers the design of a network under uncertainties brought by the fluctuations in topology to meet the requirement that the network remains intact up to a certain number of faults occurring anywhere in the network. Recently, the authors proposed a new planning methodology called Generalized Survivable Network that tackles the network design problem under both varying traffic requirements and fluctuations of topology. Although all the above network planning problems handle various kinds of uncertainties, it is hard to find a generic framework under more general uncertainty conditions that allows a more systematic way to solve the problems. With a unified framework, the seemingly diverse models and algorithms can be intimately related and possibly more insights and improvements can be brought out for solving the problem. This motivates us to seek a generic framework for solving the network planning problem under uncertainties. In addition to reviewing the various network planning problems involving uncertainties, we also propose that a unified framework based on robust optimization can be used to solve a rather large segment of network planning problem under uncertainties. Robust optimization is first introduced in the operations research literature and is a framework that incorporates information about the uncertainty sets for the parameters in the optimization model. Even though robust optimization is originated from tackling the uncertainty in the optimization process, it can serve as a comprehensive and suitable framework for tackling generic network planning problems under uncertainties. In this paper, we begin by explaining the main ideas behind the robust optimization approach. Then we demonstrate the capabilities of the proposed framework by giving out some examples of how the robust optimization framework can be applied to the current common network planning problems under uncertain environments. Next, we list some practical considerations for solving the network planning problem under uncertainties with the proposed framework. Finally, we conclude this article with some thoughts on the future directions for applying this framework to solve other network planning problems.

Computer networking is taught for some time at universities. A network is a complex mix of applications, communications protocols and link technologies, traffic flows and routing algorithms. Teaching the networking concept, the network design process is a challenging task, requiring designers to balance user performance expectations with costs and capacities. One of the obvious approaches employed to deal with its complexity is through the use of modelling and simulation techniques. This paper examines three best educational tools that can be used in the Computer Networking course at Cardiff Metropolitan University or any University for educational purpose. The paper demonstrates that a successful teaching programme needs to combine a range of teaching tools to achieve its aims. Analysing various aspects of the course provides evaluation of the overall success of the tools. Many network design and simulation tools have been studied. Based on our research and experiment, the best educational tools were selected that could be used for the purpose of teaching in the area of computer communications networks. The wide area network modelling tool Delite, the network simulator ns-3, the topology generation tool Brite can be used together to teach students the networking concepts. These tools can not only help students to understand computer network principles but also improve their network practical skills. Currently there are various tools available that are created by different companies and groups of researchers in academia and that are intended for use as practical and/or educational tools for network design including security issues. To make this task easy, different users, researchers and companies have developed different network modelling and simulation (MS) tools. Very often, such tools are addressing different issues in the network design process which are complementary to each other. It would be useful for learning and improving the network design process by allowing the use of a variety of tools.

There are available commercial and education network analysis, design, simulation and discovery tools in the market. They help the users/designers in many aspect but different tools are developed for different purposes. Thus, very often such tools are addressing different issues in the network design process, which are complementary to each other. Therefore, these tools can be used in a manner of complementing to each other to cover all aspects of user requirement and because of that there is a genuine need to integrate such tools. This paper is dedicated to the problem of integrating such independently developed network planning, network design and network simulation tools. It is looking at the problem of network meta description language as well as at principles of defining such language using current experience of various tools. Examples of the meta language definitions are shown as well as principles of building a software for conversion between different network models are illustrated.

During the planning of communication networks, the routing decision process (distributed and online) often remains decoupled from the network design process, that is, resource installation and allocation‐planning process (centralized and offline). To reconcile both processes and take into account demand variability, we generalize the capacitated multicommodity fixed charge network design class of problems by including different types of fixed costs (installation and maintenance costs) and variable costs (routing costs) but also variable traffic demands over multiple periods. However, conventional integer programming methods can typically solve only small to medium size instances of this problem. Two major difficulties are encountered when using commercial solvers to solve the associated mixed integer programs: (i) problems are large scale and even solving the linear relaxation of the problem can be challenging; and (ii) the solver hardly find good feasible solutions for medium to large scale instances. As an alternative, we propose a Lagrangian approach for computing a lower bound by relaxing the flow conservation constraints such that the Lagrangian subproblem itself decomposes by node. Though this approach yields one subproblem per network node, solving the Lagrangian dual by means of the bundle method remains a complex computational tasks. However, it always provides a lower bound on the optimal solution. Moreover, based on this relaxation, we propose a Lagrangian heuristic that makes the approach more robust than a black‐box usage of a Mixed Integer Programming (MIP) solver. © 2016 Wiley Periodicals, Inc. NETWORKS, Vol. 69(1), 110–123 2017

An overview of the key topics discussed at the 13th International Teletraffic Congress (ITC13) held in Copenhagen, Denmark, in June 1991, particularly the sessions on network design and planning, is given. Nineteen papers were presented at these sessions. Four issues that are of particular importance to ISDN design and planning are emphasized: design of networks with digital information transfer capabilities; design of networks with advanced network/traffic control techniques; use of GOS and reliability objectives for network design and planning; and design of intelligent networks. >

In this chapter, the author will first introduce in Section 4.1 a brief overview of various approaches and processes for network analysis, architecture, and design. Details of the network analysis, architecture, and design processes will be sequentially presented in Sections 4.2-4.4.As a typical network-design model, the hierarchical design approach will be discussed in detail in Section 4.5 along with its layers in Section 4.6. Various network-design approaches and their evolution will be summarized in Section 4.7. Finally, Section 4.8 will provide further discussion on network management and security.

An end to end Deep Neural Network for iris segmentation in unconstrained scenarios

To design a network as big as SANReN network design goals need to be determined. The network design process is an iterative one that follows a top-down approach. The network design lifecycle is a continuous process that seeks improvement of the network design so that it better addresses business needs and goals. This paper provides an overview of the network design goals model that provides a process for determining network design goals for an NREN. The model is instantiated in the SANReN environment. The network design goals may be slightly different to a commercial service provider but the process for determining network design goals for a commercial service provider can be adapted for SANReN.

In today's environment where traffic demands within a network are increasing rapidly, planning and designing a network are assuming great importance. Rapidly rising traffic within the network is leading to network congestion, requiring solutions to cope with the increasing demand. We address the question of network planning and design, focusing in particular on alleviation of congestion at digital-cross connect systems (DCSs) located at the nodes of a broadband transport network. We describe a constrained routing mechanism as part of a new design strategy, employing unique dynamically changing routing constraints. Also critical in network design and planning is the knowledge of DCS capacity lost to tie-trunks, when the requirement for DCS at a given node exceeds unity, and the DCSs need to be tied together to facilitate proper cross-connects. Therefore, this paper also provides a tie-trunk analysis, leading to mathematical expressions, which can act as useful guides in the judicious planning of DCSs at the nodes of the given network.

Risk assessment and management for supply chain networks: A case study

What is simulation good for and how do you use it? Simulation can be applied to a wide variety of network planning and design issues. This paper describes a number of such issues of interest, suggesting the most relevant simulated performance and the benefits derived from a simulated network performance analysis and then demonstrates the simulation technology through a detailed case study using Plan NetTM.

The network planning aims to allow the maximum number of users and throughput in a network. This imposes a demanding performance requirement on the new relay-based architecture for Mobile WiMAX, in which the capacity estimation is complex. In the network design process, where interference avoidance plays an important role, WiMAX supports reconfiguration of the subchannel usage with some frequency reuse schemes and subchannel allocation techniques already proposed in the standard and existing literature. However, these fixed strategies are not the most suitable for multihop scenarios, where some of the advantages that relay can provide are network load balancing or capacity improvement in variable conditions. The scope of this paper is first, to describe and evaluate the main two frame structures proposed in the IEEE 802.16j draft to allow multihop communications; second, to analyze the capacity improvement provided by a new optimization framework for frequency planning which considers the relay WiMAX specific characteristics that influence this process. In addition, we introduced efficient capacity calculations that will allow intensive system level simulations in a Mobile WiMAX multihop environment. Numerical results are given for various configurations allowing interesting observations about WiMAX radio efficiency. These results can be used as an order of magnitude of the real case of IEEE 802.16j network design.

The railway plays an essential role in urban and intercity transport of goods and people. Intercity and urban rail transit infrastructures contribute to the economic and environmental sustainability of global economies. Those infrastructures can be modeled as complex networks, so that we can evaluate system properties of the network structure. This stream of research has focused on the topological analysis of global network structure, but little research exists that examines how local network structures affect system properties. The local structure of complex networks can be examined with network motif analysis, as those network motifs are the building blocks of networked systems. Nevertheless, there has been scarce attention given to local network properties in rail transit networks. We contribute to covering this gap in the literature with a literature review of motif analysis research and its application to weighted and unweighted rail transit networks, also covering the current state-of-the-art of network motif decomposition and analysis. We demonstrate that network motif analysis is not only applicable, but also beneficial for the design and planning of rail transit networks, enhancing their sustainability by improving efficiency, reducing environmental impact, and optimizing resource allocation. Based on our findings, we propose future research directions that involve applying motif analysis to enhance the sustainability features of both unweighted and weighted rail transit networks.

With the rapid development of computer network, the construction of campus network is the inevitable choice of the development of information network. The campus network system is a very large and complicated system. It is not only for modern teaching, integrated information management and office automation series of applications to provide basic operating platform, but also to provide a variety of application services, so that information can be timely and accurate delivery. The campus network construction in the application of network technology is the important branch of LAN technology to build and management. This paper introduces the goal of campus network design and the selection of network technology, network equipment selection and so on, and gives the concrete network topology diagram through the example of the campus network design and construction process. The study also explains how to plan the formation of campus network efficiently and safely.

Dynamic Modeling in Design and Operation Safety Checking of Large Scale Pipeline Networks