A PCIe bus technology is a high-performance bus technology that is used for interconnection between a processor and a peripheral device. A PCIe bus uses a point-to-point serial connection, can provide a higher connection speed with fewer data lines when compared with a PCI bus, and is widely applied to a built-in device of a desktop computer, a notebook computer, a server, communications and a workstation, and the like.
One PCIe domain usually includes a root complex (Root Complex), a switch (Switch), an endpoint (Endpoint), and a bridge (PCIe bridge). The root complex is used for connection between a processor and an input/output (I/O) device; the switch supports peer-to-peer communications between different endpoints; the bridge is used for connecting the PCIe to another PCI bus standard (such as PCI/PCI-X); the endpoint is a PCIe endpoint device, such as a PCIe network interface card device, a serial port card device, or a storage card device. However, according to PCIe bus specifications, one PCIe domain has only 256 PCIe buses at most; each PCIe bus includes 32 PCIe device numbers at most; each device number includes eight function numbers at most; each function number corresponds to one PCIe device at most. Therefore, in an existing PCIe domain system, the number of PCIe devices is restricted by 256 buses.