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Internet Small Computer Systems Interface (iSCSI)
RFC 3720

Document type: RFC - Proposed Standard (April 2004; Errata)
Obsoleted by RFC 7143
Document stream: IETF
Last updated: 2013-03-02
Other versions: plain text, pdf, html

IETF State: (None)
Consensus: Unknown
Document shepherd: No shepherd assigned

IESG State: RFC 3720 (Proposed Standard)
Responsible AD: Allison Mankin
Send notices to: <ElizabethRodriguez@ieee.org>, <black_david@emc.com>

Network Working Group                                          J. Satran
Request for Comments: 3720                                       K. Meth
Category: Standards Track                                            IBM
                                                          C. Sapuntzakis
                                                           Cisco Systems
                                                          M. Chadalapaka
                                                     Hewlett-Packard Co.
                                                              E. Zeidner
                                                                     IBM
                                                              April 2004

           Internet Small Computer Systems Interface (iSCSI)

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

Abstract

   This document describes a transport protocol for Internet Small
   Computer Systems Interface (iSCSI) that works on top of TCP.  The
   iSCSI protocol aims to be fully compliant with the standardized SCSI
   architecture model.

   SCSI is a popular family of protocols that enable systems to
   communicate with I/O devices, especially storage devices.  SCSI
   protocols are request/response application protocols with a common
   standardized architecture model and basic command set, as well as
   standardized command sets for different device classes (disks, tapes,
   media-changers etc.).

   As system interconnects move from the classical bus structure to a
   network structure, SCSI has to be mapped to network transport
   protocols.  IP networks now meet the performance requirements of fast
   system interconnects and as such are good candidates to "carry" SCSI.

Satran, et al.              Standards Track                     [Page 1]
RFC 3720                         iSCSI                        April 2004

Table of Contents

   1.  Introduction. . . . . . . . . . . . . . . . . . . . . . . . .   9
   2.  Definitions and Acronyms. . . . . . . . . . . . . . . . . . .  10
       2.1.   Definitions. . . . . . . . . . . . . . . . . . . . . .  10
       2.2.   Acronyms . . . . . . . . . . . . . . . . . . . . . . .  14
       2.3.   Conventions. . . . . . . . . . . . . . . . . . . . . .  16
              2.3.1.    Word Rule. . . . . . . . . . . . . . . . . .  16
              2.3.2.    Half-Word Rule . . . . . . . . . . . . . . .  17
              2.3.3.    Byte Rule. . . . . . . . . . . . . . . . . .  17
   3.  Overview. . . . . . . . . . . . . . . . . . . . . . . . . . .  17
       3.1.   SCSI Concepts. . . . . . . . . . . . . . . . . . . . .  17
       3.2.   iSCSI Concepts and Functional Overview . . . . . . . .  18
              3.2.1.    Layers and Sessions. . . . . . . . . . . . .  19
              3.2.2.    Ordering and iSCSI Numbering . . . . . . . .  19
                        3.2.2.1.   Command Numbering and
                                   Acknowledging . . . . . . . . . .  20
                        3.2.2.2.   Response/Status Numbering and
                                   Acknowledging . . . . . . . . . .  23
                        3.2.2.3.   Data Sequencing   . . . . . . . .  24
              3.2.3.    iSCSI Login. . . . . . . . . . . . . . . . .  24
              3.2.4.    iSCSI Full Feature Phase . . . . . . . . . .  25
                        3.2.4.1.   Command Connection Allegiance . .  26
                        3.2.4.2.   Data Transfer Overview. . . . . .  27
                        3.2.4.3.   Tags and Integrity Checks . . . .  28
                        3.2.4.4.   Task Management . . . . . . . . .  28
              3.2.5.    iSCSI Connection Termination . . . . . . . .  29
              3.2.6.    iSCSI Names. . . . . . . . . . . . . . . . .  29
                        3.2.6.1.   iSCSI Name Properties . . . . . .  30
                        3.2.6.2.   iSCSI Name Encoding . . . . . . .  31
                        3.2.6.3.   iSCSI Name Structure. . . . . . .  32
                                   3.2.6.3.1.  Type "iqn." (iSCSI
                                               Qualified Name) . . .  32
                                   3.2.6.3.2.  Type "eui." (IEEE
                                               EUI-64 format). . . .  34
              3.2.7.    Persistent State . . . . . . . . . . . . . .  34
              3.2.8.    Message Synchronization and Steering . . . .  35

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