DA: Datamover Architecture for the Internet Small Computer System Interface (iSCSI)
RFC 5047

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• 05

Network Working Group                                     M. Chadalapaka
Request for Comments: 5047                                            HP
Category: Informational                                       J. Hufferd
                                                            Brocade Inc.
                                                               J. Satran
                                                                     IBM
                                                                 H. Shah
                                                    Broadcom Corporation
                                                            October 2007

                    DA: Datamover Architecture for
         the Internet Small Computer System Interface (iSCSI)

Status of This Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Abstract

   The Internet Small Computer System Interface (iSCSI) is a SCSI
   transport protocol that maps the SCSI family of application protocols
   onto TCP/IP.  Datamover Architecture for iSCSI (DA) defines an
   abstract model in which the movement of data between iSCSI end nodes
   is logically separated from the rest of the iSCSI protocol in order
   to allow iSCSI to adapt to innovations available in new IP
   transports.  While DA defines the architectural functions required of
   the class of Datamover protocols, it does not define any specific
   Datamover protocols.  Each such Datamover protocol, defined in a
   separate document, provides a reliable transport for all iSCSI PDUs,
   but actually moves the data required for certain iSCSI PDUs without
   involving the remote iSCSI layer itself.  This document begins with
   an introduction of a few new abstractions, defines a layered
   architecture for iSCSI and Datamover protocols, and then models the
   interactions within an iSCSI end node between the iSCSI layer and the
   Datamover layer that happen in order to transparently perform remote
   data movement within an IP fabric.  It is intended that this
   definition will help map iSCSI to generic Remote Direct Memory Access
   (RDMA)-capable IP fabrics in the future comprising TCP, the Stream
   Control Transmission Protocol (SCTP), and possibly other underlying
   network transport layers, such as InfiniBand.

Chadalapaka, et al.          Informational                      [Page 1]
RFC 5047                           DA                       October 2007

Table of Contents

   1. Motivation ......................................................4
      1.1. Intent .....................................................4
      1.2. Interpretation of Requirements .............................5
   2. Definitions and Acronyms ........................................5
      2.1. Definitions ................................................5
      2.2. Acronyms ...................................................6
   3. Architectural Layering of iSCSI and Datamover Layers ............7
   4. Design Overview .................................................9
   5. Architectural Concepts .........................................10
      5.1. iSCSI PDU Types ...........................................10
           5.1.1. iSCSI Data-Type PDUs ...............................10
           5.1.2. iSCSI Control-Type PDUs ............................11
      5.2. Data_Descriptor ...........................................11
      5.3. Connection_Handle .........................................11
      5.4. Operational Primitive .....................................12
      5.5. Transport Connection ......................................13
   6. Datamover Layer and Datamover Protocol .........................13
   7. Functional Overview ............................................14
      7.1. Startup ...................................................14
      7.2. Full Feature Phase ........................................15
      7.3. Wrap-up ...................................................15
   8. Operational Primitives Provided by the Datamover Layer .........16
      8.1. Send_Control ..............................................16
      8.2. Put_Data ..................................................17
      8.3. Get_Data ..................................................17
      8.4. Allocate_Connection_Resources .............................18
      8.5. Deallocate_Connection_Resources ...........................19
      8.6. Enable_Datamover ..........................................19
      8.7. Connection_Terminate ......................................20
      8.8. Notice_Key_Values .........................................20
      8.9. Deallocate_Task_Resources .................................20
   9. Operational Primitives Provided by the iSCSI Layer .............21
      9.1. Control_Notify ............................................21