Relay connection unit

A relay connection unit, to be mounted on a car, in which a network is formed by interposing said relay connection unit between buses to which electronic control units are connected so that said relay connection unit relays messages sent and received between said electronic control units belonging to different buses,

• said relay connection unit comprising:
• a network management processing circuit for executing a network management function;
• and
• a storage means for storing a specification condition of a network management function held by said network management processing circuit and a condition, of state transition conditions between functions, which may be altered by parameterizing said specification condition and said condition which may be altered,
• wherein said network management processing circuit reads out said parameters from said storage means when said relay connection unit actuates and executes said network management function by using said parameters.