Patent ID: 7516335

Claim:
A network control device that sets a normal mode and an energy-saving mode in a system, the system including a controller that includes a main Central Processing Unit (CPU); and an interface controller that includes the network control device and a sub CPU, and is connected to a network, wherein both the controller and the interface controller operate in the normal mode, and power to the controller is shut down in the energy-saving mode, the network control device comprising: a network filter configured to determine whether data included in the packet corresponds to predetermined data based on an attribute of the data when the system receives a packet transferred through the network; and a control unit configured to enable and disable a function of the network filter, wherein the control unit disables the function when the system is in the normal mode after the system is powered on, enables the function when the system is in the energy-saving mode, and disables the function when the system transits from the energy-saving mode to the normal mode, wherein after leaving the normal mode, the system transits to an energy saving standby mode, and remains during a grace time in the energy saving standby mode, where the network filter remains active during the grace time to detect a signal requesting a return to the normal mode.