Interface card, network device having the same and control method thereof

An image forming apparatus comprising:

• a printing engine;
• and
• a network interface unit coupled to the printing engine and capable of transitioning between a sleep mode and an active mode, the network interface unit including a transmitter-receiver to transmit output packet data to an external device and to receive input packet data from the external device, an Ethernet controller to process input packet data received via the transmitter-receiver, and a processor to process input packet data forwarded from the Ethernet controller, including printing packet data,
• wherein, if the input packet data received via the transmitter-receiver during the sleep mode is a multicast packet data and the received multicast packet data can be processed by the network interface unit without transitioning to the active mode, the network interface unit generates a respondent packet data in response to the received multicast packet data and transmits the respondent packet data via the transmitter-receiver without transitioning to the active mode,
• if the input packet data received via the transmitter-receiver during the sleep mode is printing packet data, the network interface unit transitions from the sleep mode to the active mode to enable the processor to process the printing packet data.