A method for operating an Internet-Protocol-based functional system in a vehicle with at least two system units separatably connected to one another in which a local IP address is respectively allocated to a first system unit and to a second system unit and data are transmitted between the first system unit and the second system unit with a reproduction rule for the purpose of carrying out a first function, wherein one of the system units acts as a transmitting system unit and the other system unit acts as a receiving system unit. The data are evaluated in the receiving system unit with the reproduction rule, the reproduction rule is used to refer to a memory location of a memory associated with the execution program code for the first function, and the first function is carried out via the receiving system unit using the data in the reproduction rule.