US Patent 7574529 Addressing logical subsystems in a data storage system

A method for transferring data over a network operating in accordance with a protocol, such as the ESCON protocol, that supports a limited logical address range includes establishing a logical path over the network from a host or other device to a second device, such as a storage system, using path logical addresses within the given logical address range. A virtual path is created over the logical path to carry the data from the source to the target, wherein the target logical subsystem has a subsystem logical address which is outside the given logical address range.