Recent advances in photonic communication networks require planning, modelling and simulation tools of ever increasing scope and complexity. Based on valid and credible models, simulators are used heavily to investigate and assess new solutions before implementing testbeds and field trials. On the other hand, tools relying on heuristics algorithms or analytical models are widely used for network planning and dimensioning. This chapter reviews some recent trends in conception and utilisation of tools for modelling and planning, and reports several developments performed with commercial or academic tools and frameworks within the COST action 291.