A switch mechanism for switching signals at inputs onto outputs and switching networks for interlinking first and second transmission media. Switching networks for interlinking first and second transmission media for the transmission of signals in frequency-division or space-division multiplex have a substantially simpler architecture in comparison to known switching networks. To that end, the switching networks are constructed with a new switch mechanism composed of a plurality of adjustable frequency converters of the input side, of a means for distributing the signals and of doubly adjustable frequency converters of the output side and/or of a plurality of doubly adjustable frequency converters of the input side, a means for distributing the signals and adjustable frequency converters of the output side. A simpler structure can be achieved in a known switching network of the Clos type in that shared-medium switches of two different types are employed. The switch mechanism can be used in electrical and optical switching systems.