A network node (1) with a communication unit (2), which is provided for the implementation of a communication protocol for the purpose of communication with other network nodes via a communication medium (5), and with a bus monitor (3), which, mutually independently, each implement an access time schedule contained in a configuration data record, and which each make available, in accordance with the access time schedule, a release signal for a bus driver (4) provided in the network node (1), which evaluates these two signals and, in the event that the two release signals do not coincide, blocks the access of the network node (1) to the communication medium (5).