A system and method are disclosed to prevent a reduction in the number of I/O devices which can be connected when building a PCIe topology by connecting I/O devices to a computer via a PCIe switch. A switch with which a computer and I/O devices are connected includes: a first PCI-PCI bridge which is positioned on the computer side; a second PCI-PCI bridge which is positioned on the I/O device side; trapper units which trap packet data which is inputted into the switch; a packet routing unit which transfers packet data to the I/O devices; and a management processor which is connected to the trapper units and provides the computer a virtual PCI-PCI bridge and a virtual link by execution of a program. The trapper units adjudicate the destination of the packet data which is transferred from the computer.