Optical crossconnects: their impact on optical networking

We discuss the relationship between the characteristics of optical crossconnects and add-drop multiplexers, and the characteristics of the optical networks in which they are used. Opaque crossconnect allow networks that are flexible and simple to manage, but have a high cost in money, power and space. Transparent crossconnects, in particular the wavelength-selective crossconnect, reduce these costs, and can achieve comparable network performance, but require more sophisticated and unproven network management.