A method of performing an input/output (I/O) processing operation includes obtaining information relating to an I/O operation at a channel subsystem in the host computer system, the channel subsystem including at least one channel having a channel processor and a local channel memory, generating addressing information and forwarding the addressing information to a network interface between the channel subsystem and at least one I/O device, the addressing information specifying a location in the local channel memory. The method also includes forwarding an I/O command message to the at least one I/O device via the network interface, receiving a data transfer request from the network interface that includes the addressing information, accessing one of a plurality of address control words (ACWs), each ACW specifying an address of a location in a host computer memory, and routing the data transfer request to the host memory location specified in the ACW.