HP StorageWorks 1510i Modular Smart Array iSCSI concepts and deployment guide (431338-002, July 2008)

1iSCSIoverview
iSCSI is a transport protocol that operates over TCP/IP.
The following sections define some industry-standard concepts:
• iSCSI protocol overview
•iSCSIPDUoverview
•iSCSIlayeringoverview
• iSCSI sessions and TCP connections overview
•iSCSIloginoverview
• iSCSI network entities, portals, and nodes overview
iSCSI protocol overview
NOTE:
This section
provides a brief, high-level overview of the iSCSI protocol as defined by the Internet Small
Computer Sy
stems Interface RFC 3720. For more information on the iSCSI protocol specification, see RFC
3720 on the Internet Engineering Task Force website: h
ttp://www.ietf.org/rfc/rfc3720.
SCSI (Small Computer Systems Interface) is a widely implemented family of protocols used for
communication with I/O devices, particularly storage devices. SCSI is a client-server architecture, where
clients of a SCSI interface are called initiators. Initiators issue SCSI commands to request services from
targets. Targets are typically components, or logical units, on a server. A SCSI transport maps the
client-server SCSI protocol to a specific interconnect. Initiators are one endpoint of a SCSI transport and
targets are the other endpoint. The SCSI protocol has been mapped over various transports, including
Parallel SCSI and Fibre Channel.
iSCSI is a transport protocol for SCSI, operating at the same level as Parallel SCSI and Fibre Channel.
iSCSI is a storage transport protocol developed by the Internet Engineering Task Force (IETF) for
transporting SCSI packets over TCP/IP. iSCSI provides an interoperable solution that takes advantage
of existing Internet infrastructure and Internet management facilities. iSCSI does not have the distance
limitations associated with the Fibre Channel storage transport. The iSCSI protocol enables the transport
of Block I/O over IP Networks. It operates on top of TCP by encapsulating SCSI commands in a TCP/IP
stream.
The following image illustrates and groups some of the commonly used transport protocols:
1510i Modular Smart Array iSCSI concepts and deployment guide
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