This work treats a typical Brazilian school timetabling problem, that consists of scheduling a set of lectures and teachers in a prefixed period of time, satisfying a set of operational requirements. We applied a basic GRASP heuristic, followed by a pathrelinking improvement. The algorithms use a local search procedure that interleaves two types of movements and a path-relinking strategy that is enhanced with a local search procedure. They were tested with real instances and proved to be good approaches to treat this problem. Although some restrictions are specific to the Brazilian educational institutions, the same ideas can inspire similar approaches for solving the school timetabling problem in other situations.

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Terabit elastic optical networking (EON) is foreseen as a viable solution to extend the lifetime of a network exploiting the available bandwidth in previously deployed optical fibers. EON is based on bandwidth-variable transponders capable of supporting multiple bit rates and/ or modulation formats according to traffic requirements and node architectures that route arbitrary channel bandwidths. Thus, EON increases the heterogeneity of the network, which may create the need for autonomic adaptive and/or cognitive techniques. In this context, the software-defined networking (SDN) paradigm emerges as an opportunity to enable such techniques thanks to the centralized view of the network by decoupling the control plane and the data plane. This paper surveys different activities carried out at the Optical Technologies Division in Centro de Pesquisa e Desenvolvimento em Telecomunicações, Brazil. We review an optical transport SDN controller for virtual optical networks that supports two adaptive algorithms. First, the autonomic flexible transponder reconfigures the transmission modulation format according to a threshold level. Second, the adaptive global spectrum equalization reconfigures the wavelengths' attenuation profiles applied at the optical nodes to improve the signals' optical signal-to-noise ratio (OSNR) at reception. Finally, we report experimental results of an in-band OSNR monitor for advanced modulation formats.

In flex-grid (elastic) networks, the spectrum can be allocated at a much finer granularity than it can be allocated in WDM networks. However, the dynamic establishment and tear down of lightpaths yields to the fragmentation of the spectrum with consequent increase in blocking of requests for connection establishment. Therefore, it is of paramount importance that allocation decisions try to mitigate the fragmentation problem. In line with that, this paper introduces the Multigraph Shortest Path Algorithm for novel Routing and Spectrum Allocation (RSA) in elastic networks. Results indicate that the joint use of the new algorithm with proposed cost functions can produce bandwidth blocking ratio four orders of magnitude lower than existing RSA algorithms.

Information and Communication Technology activities consumed 4% of the world energy in 2009, and such consumption will continue to increase due to the traffic growth of the Internet predicted for the next years. Techniques to make the core of the network more energy efficient has been proposed, among them, green routing has been considered a promising technique. This paper proposes a novel Routing, Modulation Level and Spectrum Assignment (RMLSA) algorithm for elastic optical networks that considers the energy consumption of potential routes. Results indicate that this algorithm can save up to 34% energy and produce bandwidth blocking ratio two orders of magnitude lower than existing energy aware RMLSA algorithms.