SAN (Extension Protocol & Protocol Stack) ROHIT SINGH

WHAT IS SAN? A storage area network (SAN) is a dedicated network that provides access to consolidated, block level data storage. A SAN does not provide file abstraction, only block-level operations. A SAN typically has its own network of storage devices that are generally not accessible through the local area network (LAN) by other devices.

SAN Extension Protocol SANs can use different protocol and transport stacks to transfer SCSI commands and data. FCIP and iSCSI stacks support block-level storage for remote devices. Both FCIP and iSCSI are used to carry SCSI commands and status. Each uses the TCP/IP protocol suite as a transport mechanism.

Fibre channel over IP FCIP is Fibre Channel encapsulated in IP. Its purpose is to provide connectivity between two separate SANs over a WAN, as shown in Figure below . FCIP is a tunneling protocol. The Fibre Channel packet is encapsulated into FCIP

iSCSI iSCSI is a protocol used to carry SCSI commands, responses, and data over an IP network. File access is at the block level. Figure below shows a connection that uses iSCSI between the iSCSI host and Switch B. DiffieHellman Challenge Handshake Authentication Protocol (DH-CHAP) authentication should also be used to enhance security on the LAN.

SAN Protocol Stack Figure below compares FCoE with other SCSI-based SAN technologies, such as iSCSI and FCIP. The first thing that stands out is that FCoE, FCIP, and Fibre Channel all use the Fibre Channel Protocol (FCP) and Fibre Channel framing. The iSCSI protocol is even more different. The main differentiator between FCoE and iSCSI is the easy integration of FCoE in Fibre Channel SANs. It does not use FCP but encapsulates SCSI directly into TCP/IP

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