US Patent 7945722 Routing data units between different address domains

Methods for routing data units and PCI Express switches are disclosed. A plurality of devices may be coupled to a corresponding plurality of physical interfaces, each physical interface having a respective configurable status and a respective address domain, wherein in a first status the interface is transparent, and in a second status the interface is non-transparent. The status of each of the plurality of physical interfaces may be set as transparent or non-transparent. Data units may be switched between the physical interfaces using mapped address input/output, switching data units including masking the address domain for the interfaces configured as non-transparent.