In a control network for a rail vehicle, control units of the rail vehicle are connected to each other in a ring shape via at least two communication paths. A first control unit transmits user data via a communication path in a first direction to a second control unit and test data associated with the user data for checking the user data via another communication path in a second direction opposite to the first direction to the second control unit. The second control unit can thus detect manipulation of data by a third party.