A group of K data units received consecutively is arranged by a first device. The arranged K data units are sent to the inputs of M devices, and a group of Hj data units of the arranged K data units are transferred by a device j of the M devices. The data units sent to the devices of the M devices are arranged such that no two inputs of the devices of the M devices transferring receive the same data unit at any moment. A second device combines and arranges the K data units from the outputs of the M devices such that the K data units appear at the output of the second device consecutively, and a length of time gap between data units in a data switching network is shortened.