iSCSI Internet SCSI PDU
The iSCSI layer encapsulates the SCSI CDB into a iSCSI Protocol Data Unit (PDU) and forwards it to the Transmission Control Protocol (TCP) layer
It also extracts the CDB from an iSCSI PDU received from the TCP layer, and forwards the CDB to the SCSI layer
iSCSI mapping provides the SCSI-3 command layer with a reliable transport