The issue of energy-aware traffic engineering has become prominent in telecommunications industry in the last years. This paper presents a two-criteria network optimization problem, in which routing and bandwidth allocation are determined jointly, so as to minimize the amount of energy consumed by a telecommunication infrastructure and to satisfy given demands represented by a traffic matrix. A scalarization of the criteria is proposed and the choice of model parameters is discussed in detail. The model of power dissipation as a function of carried traffic in a typical software router is introduced. Then the problem is expressed in a form suitable for the mixed integer quadratic programming (MIQP) solver. The paper is concluded with a set of small, illustrative computational examples. Computed solutions are implemented in a testbed to validate the accuracy of energy consumption models and the correctness of the proposed traffic engineering algorithm.

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The paper presents application of the Markov chain model to assess the risk affecting critical national infrastructure. A method for relating different service states to transition probabilities is shown. Then, a real-life example is thoroughly analyzed. Finally, results of a numerical test concerning this problem are provided.

Abstract-The paper compares two formulations of dynamic power management in energy-aware computer networks. In the first approach the only criterion is energy consumption, in the second there is an additional one -the quality of service. It is shown, that the second approach is appropriate when the routing problem with fixed demands is inadmissible. Fortunately, by some optimization modeling transformations it still allows for using the same standard mixed integer solvers as the first approach.

Efforts to reduce power consumption in telecommunication networks follow in two mutually related directions -design of a more efficient equipment and development of energy-aware network control strategies and protocols. The paper presents a formulation of two-criteria traffic engineering problem, which takes advantage of energy saving capabilities in software routers. The first optimization criterion is the energy consumption, and the second one is the quality of service and service sustainability. Models and traffic engineering strategy were verified in laboratory experiments.