A network system comprising: dualized basic units (100, 200); a plurality of extension units (300, 400, 500, 600), each containing dualized extension Ethernet modules; said dualized extension Ethernet modules being a first extension Ethernet module (310, 410, 510, 610) and a second extension Ethernet module (320, 420, 520, 620); a first ring network connected by a first basic unit and a plurality of first extension Ethernet modules (310, 410, 510, 610); and a second ring network connected by a second basic unit and a plurality of second extension Ethernet modules (320, 420, 520, 620), characterized in that: a first extension Ethernet module (310, 410, 510, 610) is configured to transmit or receive data along a network path, wherein it is determined whether the network path is a single ring network path or a dual/dualized ring network path by: judging, by the first extension Ethernet module (310, 410, 510, 610), whether the first ring network is connected to a second extension Ethernet module (320, 420, 520, 620) using an intrinsic number of each extension Ethernet module, each extension Ethernet module being set with a different intrinsic number; determining, by the first extension Ethernet module (310, 410, 510, 610), a single ring network in which the first ring network and the second ring network are connected, upon judging, by the first extension Ethernet module (310, 410, 510, 610), that the first ring network and the second extension Ethernet module are connected; and determining, by the first extension Ethernet module (310, 410, 510, 610), a dual/dualized ring network in which the first ring network and the second ring network are independently formed, upon judging, by the first extension Ethernet module, that the first ring network and the second extension Ethernet module are not connected. dualized basic units (100, 200); a plurality of extension units (300, 400, 500, 600), each containing dualized extension Ethernet modules; said dualized extension Ethernet modules being a first extension Ethernet module (310, 410, 510, 610) and a second extension Ethernet module (320, 420, 520, 620); a first ring network connected by a first basic unit and a plurality of first extension Ethernet modules (310, 410, 510, 610); and a second ring network connected by a second basic unit and a plurality of second extension Ethernet modules (320, 420, 520, 620), characterized in that: a first extension Ethernet module (310, 410, 510, 610) is configured to transmit or receive data along a network path, wherein it is determined whether the network path is a single ring network path or a dual/dualized ring network path by: judging, by the first extension Ethernet module (310, 410, 510, 610), whether the first ring network is connected to a second extension Ethernet module (320, 420, 520, 620) using an intrinsic number of each extension Ethernet module, each extension Ethernet module being set with a different intrinsic number; determining, by the first extension Ethernet module (310, 410, 510, 610), a single ring network in which the first ring network and the second ring network are connected, upon judging, by the first extension Ethernet module (310, 410, 510, 610), that the first ring network and the second extension Ethernet module are connected; and determining, by the first extension Ethernet module (310, 410, 510, 610), a dual/dualized ring network in which the first ring network and the second ring network are independently formed, upon judging, by the first extension Ethernet module, that the first ring network and the second extension Ethernet module are not connected. judging, by the first extension Ethernet module (310, 410, 510, 610), whether the first ring network is connected to a second extension Ethernet module (320, 420, 520, 620) using an intrinsic number of each extension Ethernet module, each extension Ethernet module being set with a different intrinsic number; determining, by the first extension Ethernet module (310, 410, 510, 610), a single ring network in which the first ring network and the second ring network are connected, upon judging, by the first extension Ethernet module (310, 410, 510, 610), that the first ring network and the second extension Ethernet module are connected; and determining, by the first extension Ethernet module (310, 410, 510, 610), a dual/dualized ring network in which the first ring network and the second ring network are independently formed, upon judging, by the first extension Ethernet module, that the first ring network and the second extension Ethernet module are not connected.