To provide an information processor, an image forming device, a switchable concentrator and a network system capable of performing data communication at high speed while keeping features of conventional information processor, image forming device, switchable concentrator and network system.

A network card 634 (635) of a client network station 620 is connected respectively to a network port 610 (611), and then a device 601 transmits image data to a network interface section 7 of an image forming device 100 while a network communication driver distributes the data so that the image data are properly divided into 1/2. Or two network interface sections 7 included in an image input/output control section of the image forming device 100 are provided, each of the two network interface sections 7 is connected respectively to network ports 615, 616 and a network communication control program by which the two network interface sections 7 are controlled virtually as if to be one interface section 7 is executed by a core section.