The three main protocols for IP SANs are Fibre Channel over IP (FCIP), Internet Fibre Channel Protocol (iFCP), and Internet SCSI (iSCSI). As shown in Figure 1, the iSCSI, iFCP, and FCIP protocols support a serial SCSI-3 interface to the standard SCSI command set expected by the operating system and upper-layer applications. This allows conventional storage I/O to be performed over a high-performance gigabit transport. Serial SCSI-3 transactions are carried over TCP/IP, although only iFCP and iSCSI leverage native TCP/IP for each storage end device. Each IP storage protocol has unique requirements for discovery.