Special Purpose Communication Devices
Wavelength Division Multiplexing (WDM) means dividing a fiber optic cable into up to 10 simultaneous circuits (each up to 622 Mbps over short and 200 Mbps over long distances) (Fiber optic cable used to be able to carry one circuit at a time.)
Concentrators are a special form of statistical
multiplexers. While multiplexers have terminals attached to them, concentrators do not (multiplexing multiplexers)