• A storage protocol that enables block I/O data transfers over standard IP networks
• Encapsulates block-level serial SCSI-3 commands and data in a TCP/IP frame
• Designed to allow hosts to directly access storage over an IP infrastructure
• Joint development project of IETF and ANSI T10 committee
IP TCP iSCSI SCSI Data
The internet Small Computer Systems Interface (iSCSI) protocol defines the rules and processes to transmit and receive block storage applications over TCP/IP networks.
iSCSI enables SCSI-3 commands to be encapsulated in TCP/IP packets and delivered reliably over IP networks. • we take our data, the same as we did before, the data goes inside SCSI. • Our SCSI headers then get wrapped up inside an iSCSI header.
o That iSCSI header is the equivalent of our Fibre Channel headers. But an iSCSI header is 48 bytes long.
• The iSCSI frame then goes inside TCP which gives us guaranteed in order delivery, which will then go inside IP. • IP gives us our logical routable address.
So it’s doing exactly the same as Fibre Channel would do ⎯ it takes the SCSI command and it routes it over a physical transport. The physical transport in this instance goes over our TCP/IP network.