A media converter monitors whether a metal cable link is disconnected. If the metal cable link is disconnected, a desired invalid code other than pre-defined codes is successively transmitted toward a fiber optic cable to disconnect its link. If the metal cable link is not disconnected, a first auto negotiation is performed with the metal cable side to set a first line ability, and a second auto negotiation is performed with the fiber optic cable side based on the first line ability to set a second line ability. Subsequently, a third auto negotiation is performed again with the metal cable side based on the second line ability to finally determine the line ability between the metal and the fiber optic cables.