Patent ID: 8081638

Claim:
A communication system comprising: a switching hub capable of configuring a virtual network; and a communication apparatus connected to a network via the switching hub, wherein the switching hub includes: a first packet processing unit configured to send/receive packet data with the communication apparatus; a storage unit configured to store identification information for identifying a terminal permitted to participate in the virtual network; and a management unit configured to manage, if information received by the first packet processing unit from the communication apparatus matches the identification information stored in the storage unit, the communication apparatus to participate in the virtual network corresponding to the matched identification information; wherein the communication apparatus includes: a second packet processing unit configured to transmit/receive the packet data with the switching hub; a first control unit configured to control the communication apparatus; a second control unit configured to control the second processing unit; a power supply unit configured to supply power in one of a normal mode for supplying power to the first control unit, the second control unit, and the second packet processing unit and a power-saving mode for reducing power supplied to the first control unit lower than power in the normal mode while supplying power to the second control unit and the second packet processing unit; and a first determination unit configured to determine whether a switching condition for switching from the normal mode to the power-saving mode has been satisfied; wherein the first control unit controls, according to the determination of the determination unit that the switching condition has been established, the second packet processing unit to change from a link-up state where a communication link is established with the switching hub to a link-down state where the communication link is not established, and the power supply unit to change from the normal mode to the power-saving mode; the second control unit controls, according to the change from the normal mode to the power-saving mode, the second packet processing unit to change the link-down state to the link-up state and to transmit to the switching hub information needed by the switching hub to cause the communication apparatus to participate in the virtual network; and the second packet processing unit sets a communication speed between the communication apparatus and the switching hub when the power supply unit operates in the power-saving mode lower than a communication speed between the communication apparatus and the switching hub when the power supply unit operates in the normal mode.