Guidelines for scalable optical telecommunication networks

Optical networks based on wavelength division multiplexing (WDM) hold some promising features for application as future worldwide telecommunication transport network. Besides the obvious advantage of increased transmission capacity, optical routing of wavelengths by means of optical crossconnect nodes, allows to overcome the routing bottlenecks of electrical nodes, and enables the transport of high bandwidths at once over long distances. This paves the way to simpler and less-hierarchical networks, an important property to keep future networks manageable. In any case, not all WDM-based architectures can be simply extrapolated to a worldwide scale. Some seemingly scalable elements of these architectures saturate at some point along network expansion. This paper analyses scalability issues related to the core network.