We present in this Chapter an overviewof optical fronthauling technologies for fixed-mobile convergence in next generation 5G access networks. The Chapter first introduces the general concept of Cloud Radio Access Network, or C-RAN, then it presents the most common proposals for fronthauling, based on Digitized Radioover- Fiber, or D-RoF, according to the CPRI or OBSAI standards. The Chapter then prosecutes by presenting the very recent evolutions of D-RoF toward the "functional split" paradigm, as already available in the latest releases of the CPRI specifications. Finally, some recent research trends towards Analog RoF are presented. The Chapter is intentionally written in a tutorial way, to be used by newcomers in this field. It anyway also reports a vast set of bibliographic references to guide the interested reader toward more detailed technical presentations.