Editing Wavelength-division multiplexing (section)

===Optical cross connects (OXCs)===
{{Main|Optical cross-connect}}
{{Expand section|date=June 2008}}
When the network topology is a mesh, where nodes are interconnected by fibers to form an arbitrary graph, an additional fiber interconnection device is needed to route the signals from an input port to the desired output port. These devices are called optical crossconnectors (OXCs). Various categories of OXCs include electronic ("opaque"), optical ("transparent"), and wavelength-selective devices.