A method for implementing network virtualization, comprising: receiving, by a software defined network, SDN, controller, a virtual network creation request that carries virtual network topology information; creating, by the SDN controller, a virtual network in response to the virtual network creation request, wherein the virtual network has a topology described by the virtual network topology information, and the virtual network comprises a first virtual forwarding device and a second virtual forwarding device; establishing, by the SDN controller, a device mapping relationship, wherein the device mapping relationship comprises a mapping relationship between the first virtual forwarding device and a first physical forwarding device in a physical network, and a mapping relationship between the second virtual forwarding device and a second physical forwarding device in the physical network; and establishing, by the SDN controller, a port mapping relationship, wherein the port mapping relationship comprises a mapping relationship between a port of the first virtual forwarding device and a port of the first physical forwarding device, and a mapping relationship between a port of the second virtual forwarding device and a port of the second physical forwarding device, characterized in that the method further comprises: allocating, by the SDN controller, a virtual SDN controller to the virtual network; and registering, by the SDN controller, the first virtual forwarding device and the second virtual forwarding device with the virtual SDN controller, thereby establishing control channels between the virtual SDN controller and the first and second virtual forwarding devices. receiving, by a software defined network, SDN, controller, a virtual network creation request that carries virtual network topology information; creating, by the SDN controller, a virtual network in response to the virtual network creation request, wherein the virtual network has a topology described by the virtual network topology information, and the virtual network comprises a first virtual forwarding device and a second virtual forwarding device; establishing, by the SDN controller, a device mapping relationship, wherein the device mapping relationship comprises a mapping relationship between the first virtual forwarding device and a first physical forwarding device in a physical network, and a mapping relationship between the second virtual forwarding device and a second physical forwarding device in the physical network; and establishing, by the SDN controller, a port mapping relationship, wherein the port mapping relationship comprises a mapping relationship between a port of the first virtual forwarding device and a port of the first physical forwarding device, and a mapping relationship between a port of the second virtual forwarding device and a port of the second physical forwarding device, characterized in that the method further comprises: allocating, by the SDN controller, a virtual SDN controller to the virtual network; and registering, by the SDN controller, the first virtual forwarding device and the second virtual forwarding device with the virtual SDN controller, thereby establishing control channels between the virtual SDN controller and the first and second virtual forwarding devices. allocating, by the SDN controller, a virtual SDN controller to the virtual network; and registering, by the SDN controller, the first virtual forwarding device and the second virtual forwarding device with the virtual SDN controller, thereby establishing control channels between the virtual SDN controller and the first and second virtual forwarding devices.