A network having a plurality of subscribers has at least one message transmitter and at least one message receiver. The at least one message transmitter sends messages at predefined time intervals. The message receiver receives the messages at the predefined time intervals. A delay time of the messages is monitored on the basis of time outs. In addition, at least one of the subscribers repeatedly estimates a current delay time using a time measurement between sending out a request message and receiving a response message. The estimated delay time is compared with a predefined threshold value. If the estimated delay time exceeds the defined threshold value, an error signal is generated.