Method for synchronizing control applications via a communication network for transferring time-critical data, in which - the communication network comprises communication terminals at starting and end nodes of paths for data streams and network infrastructure devices at intermediate nodes, selected data streams being associated with control applications running on communication terminals (201, 202), - the network infrastructure devices ascertain a particular time delay (L(i)) between a scheduled time of transmission (TX P (i)) for a datagram and its actual time of transmission (TX(i)) when forwarding datagrams associated with the selected data streams, - the network infrastructure devices send particular information about the ascertained time delay to a network infrastructure device or communication terminal that is subsequent along the respective path, - the network infrastructure devices compute the scheduled time of transmission (TX P (i)) on the basis of a particular time of reception (RX(i)) of the datagrams and a time delay (L(i-1)) ascertained by a communication terminal or network infrastructure device that is precedent along the respective path, - an accumulated maximum time delay (D MAX) between starting nodes and end nodes is ascertained for a transmission of the selected data streams, - synchronization between transmission cycles of starting-node control applications and transmission cycles of end-node control applications is achieved by virtue of the starting-node control application taking the time delay ascertained by the precedent network infrastructure device, the accumulated maximum time delay and a time of transmission (TX APP) of the datagrams as a basis for ascertaining a particular start (T SYNC) of a next end-node transmission cycle. - the communication network comprises communication terminals at starting and end nodes of paths for data streams and network infrastructure devices at intermediate nodes, selected data streams being associated with control applications running on communication terminals (201, 202), - the network infrastructure devices ascertain a particular time delay (L(i)) between a scheduled time of transmission (TX P (i)) for a datagram and its actual time of transmission (TX(i)) when forwarding datagrams associated with the selected data streams, - the network infrastructure devices send particular information about the ascertained time delay to a network infrastructure device or communication terminal that is subsequent along the respective path, - the network infrastructure devices compute the scheduled time of transmission (TX P (i)) on the basis of a particular time of reception (RX(i)) of the datagrams and a time delay (L(i-1)) ascertained by a communication terminal or network infrastructure device that is precedent along the respective path, - an accumulated maximum time delay (D MAX) between starting nodes and end nodes is ascertained for a transmission of the selected data streams, - synchronization between transmission cycles of starting-node control applications and transmission cycles of end-node control applications is achieved by virtue of the starting-node control application taking the time delay ascertained by the precedent network infrastructure device, the accumulated maximum time delay and a time of transmission (TX APP) of the datagrams as a basis for ascertaining a particular start (T SYNC) of a next end-node transmission cycle.