The present invention provides a method for forwarding data in the Ethernet, an Ethernet physical layer cross apparatus, an Ethernet Media Access Control (MAC) layer cross apparatus, an Ethernet IP layer cross apparatus and cross cascade systems. In the method of the present invention includes the following features: configuring cross relationships between network device interfaces; determining whether an interface has a cross relationship with other interfaces according to the cross relationships configured after receiving data from the interface; sending the data to an interface which has a cross relationship with the interface from which the data is received if the interface from which the data is received has a cross relationship with other interfaces; and proceeding with existing forwarding processing in each layer if the interface from which the data is received does not have a cross relationship with other interfaces. The solution of the present invention dramatically reduces workload of network devices in the Ethernet and improves forwarding performance of the network devices.