In an STM-network having multiplexer units (1) and a switch (3), for changes in the traffic configuration memories (41, 49; 43, 51) must also be changed, these configuration memories being located in the multiplexer units for controlling reading and writing in intermediate FIFO-type memories (21, 23). Unsynchronized writing in the configuration memories (41, 49; 43, 51) is avoided by transmitting suitable signals between the configuration memories, in the suitable case on particular lines (53) provided therefor or otherwise by transmitting particular control messages (rec.) which are located in a time slot having a predetermined position in each transmitted frame.