Scilab is a scientific software package package that provides a strong open computing environment for engineering and scientific applications. Distributed freely via the net since 1994, Scilab is currently being used in academic and industrial environments around the world. The objective of this book is to provide an intensive description of Scilab's use, as well as a way to master its environment and programming language, the utilization of integrated graphics, the incorporation of user-provided functions, and a tour of the many application toolboxes. Scilab is considered to be the wonderful alternative of Matlab which is a commercial one. The basic Scilab programs are extended to understand the Scilab programing language, routing algorithms, congestion algorithms, topology generation methods using NARVAL and NTG Toolboxes. Network Analysis and Routing eVALuation toolbox is referenced as NARVAL and Network Topology Generator is referenced as NTG are designed on top of the Scilab environment. It has been created at the University of Luxembourg within the Interdisciplinary Centre for Security, Reliability and Trust (SnT). NARVAL permits to generate random topologies according to various algorithms such as Locality, Waxman, Barabasi Albert and hierarchical models. The user can also design his own topology by providing nodes' coordinates, visualization parameters, and also links' information that are necessary for path calculation. The combination of these functions enables to build a large range of topologies with distinct routing properties.