Scalability issues in optical networks

Since the inception of optical networking, a goal has been to create an all -optical network. The rapid breakthrough for WDM in point to point links ha s brought this prospect considerably closer, however, at the same time, que stions regarding the scalability of the all-optical network remain. In this paper, we review our recent research in this area, partly performed within the European Union project METON (METropolitan Optical Network), and discu ss the all-optical approach and different optoelectronic alternatives, main ly of the 2R (reamplify and reshape) type.