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Versions: 00 01 02 03 04 05 06 07 08 09 RFC 5048

INTERNET DRAFT                              Mallikarjun Chadalapaka
draft-ietf-ips-iscsi-impl-guide-09.txt          Hewlett-Packard Co.
                                                             Editor


Updates: RFC 3720
Intended status: Proposed Standard

                                              Expires December 2007

                  iSCSI Corrections and Clarifications


Status of this Memo
   By submitting this Internet-Draft, each author represents
   that any applicable patent or other IPR claims of which he or
   she is aware have been or will be disclosed, and any of which
   he or she becomes aware will be disclosed, in accordance with
   Section 6 of BCP 79.

   Internet-Drafts are working documents of the Internet
   Engineering Task Force (IETF), its areas, and its working
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   at http://www.ietf.org/shadow.html.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
   NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as
   described in [RFC2119].

Abstract
   iSCSI is a SCSI transport protocol and maps the SCSI
   architecture and command sets onto TCP/IP.  RFC 3720 defines





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   the iSCSI protocol.  This document compiles the
   clarifications to the original protocol definition in RFC
   3720 to serve as a companion document for the iSCSI
   implementers. This document updates RFC 3720 and the text in
   this document supersedes the text in RFC 3720 when the two
   differ.






































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   Table of Contents

   1       Definitions, Acronyms and Document Summary............. 5
   1.1     Definitions............................................ 5
   1.2     Acronyms............................................... 5
   1.3     Clarifications, Changes and New Semantics.............. 6
   2       Introduction........................................... 9
   3       iSCSI semantics for SCSI tasks........................ 10
   3.1     Residual handling..................................... 10
   3.1.1 Overview ............................................ 10
   3.1.2 SCSI REPORT LUNS and Residual Overflow .............. 11
   3.2     R2T Ordering.......................................... 12
   3.3     Model Assumptions for Response Ordering............... 13
   3.3.1 Model Description ................................... 13
   3.3.2 iSCSI Semantics with the Interface Model ............ 14
   3.3.3 Current List of Fenced Response Use Cases ........... 14
   4       Task Management....................................... 16
   4.1     Requests Affecting Multiple Tasks..................... 16
   4.1.1 Scope of affected tasks ............................. 16
   4.1.2 Clarified multi-task abort semantics ................ 16
   4.1.3 Updated multi-task abort semantics .................. 18
   4.1.4 Affected tasks shared across RFC3720 & FastAbort
   sessions ................................................... 20
   4.1.5 Implementation considerations ....................... 21
   4.1.6 Rationale behind the new semantics .................. 22
   5       Discovery semantics................................... 24
   5.1     Error Recovery for Discovery Sessions................. 24
   5.2     Reinstatement Semantics of Discovery Sessions......... 24
   5.2.1 Unnamed Discovery Sessions .......................... 25
   5.2.2 Named Discovery Sessions ............................ 25
   5.3     Target PDUs during Discovery.......................... 26
   6       Negotiation and Others................................ 27
   6.1     TPGT Values........................................... 27
   6.2     SessionType Negotiation............................... 27
   6.3     Understanding NotUnderstood........................... 27
   6.4     Outstanding Negotiation Exchanges..................... 28
   7       iSCSI Error Handling and Recovery..................... 29
   7.1     ITT................................................... 29
   7.2     Format Errors......................................... 29
   7.3     Digest Errors......................................... 29
   7.4     Message Error Checking................................ 30
   8       iSCSI PDUs............................................ 31
   8.1     Asynchronous Message.................................. 31
   8.2     Reject................................................ 31
   9       Login/Text Operational Text Keys...................... 33
   9.1     TaskReporting......................................... 33
   10      Security Considerations............................... 35
   11      IANA Considerations................................... 36
   11.1     iSCSI-related IANA registries ....................... 36
   11.2     iSCSI Opcodes ....................................... 36




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   11.3     iSCSI Login/Text Keys ............................... 39
   11.4     iSCSI Asynchronous Events ........................... 41
   11.5     iSCSI Task Management Function Codes ................ 42
   11.6     iSCSI Login Response Status Codes ................... 43
   11.7     iSCSI Reject Reason Codes ........................... 45
   11.8     iSER Opcodes ........................................ 47
   12      References and Bibliography........................... 49
   12.1     Normative References ................................ 49
   12.2     Informative References .............................. 49
   13      Editor's Address...................................... 50
   14      Acknowledgements...................................... 51
   15      Full Copyright Statement.............................. 52
   16      Intellectual Property Statement....................... 53

































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1 Definitions, Acronyms and Document Summary

1.1 Definitions

     I/O Buffer - A buffer that is used in a SCSI Read or Write
         operation so SCSI data may be sent from or received into
         that buffer. For a read or write data transfer to take
         place for a task, an I/O Buffer is required on the
         initiator and at least one required on the target.

     SCSI-Presented Data Transfer Length (SPDTL): SPDTL is the
         aggregate data length of the data that SCSI layer
         logically "presents" to iSCSI layer for a Data-in or
         Data-out transfer in the context of a SCSI task.  For a
         bidirectional task, there are two SPDTL values - one for
         Data-in and one for Data-out. Note that the notion of
         "presenting" includes immediate data per the data
         transfer model in [SAM2], and excludes overlapping data
         transfers, if any, requested by the SCSI layer.

     Third-party: A term used in this document to denote nexus
         objects (I_T or I_T_L) and iSCSI sessions which reap the
         side-effects of actions that take place in the context of
         a separate iSCSI session, while being third parties to
         the action that caused the side-effects.  One example of
         a Third-party session is an iSCSI session hosting an
         I_T_L nexus to an LU that is reset with an LU Reset TMF
         via a separate I_T nexus.


1.2 Acronyms

     Acronym        Definition

     -------------------------------------------------------------

     EDTL           Expected Data Transfer Length

     IANA           Internet Assigned Numbers Authority

     IETF           Internet Engineering Task Force

     I/O            Input - Output

     IP             Internet Protocol

     iSCSI          Internet SCSI

     iSER           iSCSI Extensions for RDMA




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   ITT            Initiator Task Tag

   LO             Leading Only

   LU             Logical Unit

   LUN            Logical Unit Number

   PDU            Protocol Data Unit

   RDMA           Remote Direct Memory Access

   R2T            Ready To Transfer

   R2TSN          Ready To Transfer Sequence Number

   RFC            Request For Comments

   SAM            SCSI Architecture Model

   SCSI           Small Computer Systems Interface

   SN             Sequence Number

   SNACK          Selective Negative Acknowledgment - also

                  Sequence Number Acknowledgement for data

   TCP            Transmission Control Protocol

   TMF            Task Management Function

   TTT            Target Transfer Tag

   UA             Unit Attention


1.3 Clarifications, Changes and New Semantics

This document specifies certain changes to [RFC3720] semantics
as well as defines new iSCSI semantics.  In addition, this
document also clarifies the [RFC3720] semantics.  This section
summarizes the contents of the document, categorizing each
section into one or more of a Clarification, a Change or a New
Semantic.

    Section 3.1.1: Clarification on iSCSI residuals computation
     general principles





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    Section 3.1.2: Clarification on iSCSI residuals computation
    with an example

    Section 3.2: Clarification on R2T ordering requirements

    Section 3.3: New Semantics for Response Ordering in multi-
    connection iSCSI sessions

    Section 4.1.2: Clarifications, Changes and New Semantics on
    multi-task abort semantics that all implementations must
    comply with

    Section 4.1.3: Changes and New Semantics (FastAbort
    semantics) on multi-task abort semantics that
    implementations should use for faster error recovery

    Section 4.1.3.1: Changes in iSCSI Clearing effects semantics
    resulting out of new FastAbort semantics

    Section 4.1.4: New Semantics on third-party session
    interactions with the new FastAbort semantics

    Section 4.1.5: Clarification on implementation considerations
    related to outstanding data transfers in order to realize
    right iSCSI protocol behavior

    Section 4.1.6: Clarification on the intent behind FastAbort
    semantics (not clarifications to [RFC3720] semantics)

    Section 5.1: Clarification on error recovery semantics as
    applicable to Discovery sessions

    Section 5.2.1: Clarification and New Semantics on applying
    ISID RULE ([RFC3720]) to Unnamed Discovery Sessions

    Section 5.2.2: Clarification on applying ISID RULE to Named
    Discovery Sessions

    Section 5.3: Clarification on allowed PDU types and target
    Logout notification behavior on a Discovery session

    Section 6.1: Clarification on the legality of TPGT value of
    zero

    Section 6.2: Clarification on the negotiating order of
    SessionType with respect to other keys

    Section 6.3: Clarification on NotUnderstood negotiation
    response on declarative keys and the implied semantics





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    Section 6.4: Clarification on the number of legal outstanding
    negotiation PDUs (Text or Login-related)

    Section 7.1: Clarification on usage of ITT value of
    0xffffffff

    Section 7.2: Clarification on what constitute format errors
    for the purpose of error recovery defined in [RFC3720]

    Section 7.3: Change in error recovery semantics for the case
    of discarding unsolicited PDUs

    Section 7.4: Clarification on the intended level of error
    checking on inbound PDUs

    Section 8.1: New Semantics for a new AsyncEvent code

    Section 8.2: Change of legal status for Reject reason code
    0x0b, it is now deprecated

    Section 9.1: New Semantics for a new text key TaskReporting



























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2 Introduction

Several iSCSI implementations had been built after [RFC3720] was
published and the iSCSI community is now richer by the resulting
implementation expertise.  The goal of this document is to
leverage this expertise both to offer clarifications to the
[RFC3720] semantics and to address defects in [RFC3720] as
appropriate.  This document intends to offer critical guidance
to implementers with regard to non-obvious iSCSI implementation
aspects so as to improve interoperability and accelerate iSCSI
adoption.  This document, however, does not purport to be an
all-encompassing iSCSI how-to guide for implementers, nor a
complete revision of [RFC3720].  This document instead is
intended as a companion document to [RFC3720] for the iSCSI
implementers.


iSCSI implementers are required to reference [RFC3722] and
[RFC3723] in addition to [RFC3720] for mandatory requirements.
In addition, [RFC3721] also contains useful information for
iSCSI implementers.  The text in this document, however, updates
and supersedes the text in [RFC3720] whenever there is such a
question.
























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3 iSCSI semantics for SCSI tasks

3.1 Residual handling

Section 10.4.1 of [RFC3720] defines the notion of "residuals"
and specifies how the residual information should be encoded
into the SCSI Response PDU in Counts and Flags fields.  Section
3.1.1 clarifies the intent of [RFC3720] and explains the general
principles.  Section 3.1.2 describes the residual handling in
the REPORT LUNS scenario.

3.1.1 Overview

SCSI-Presented Data Transfer Length (SPDTL) is the term this
document uses (see section 1.1 for definition) to represent the
aggregate data length that the target SCSI layer attempts to
transfer using the local iSCSI layer for a task.  Expected Data
Transfer Length (EDTL) is the iSCSI term that represents the
length of data that the iSCSI layer expects to transfer for a
task. EDTL is specified in the SCSI Command PDU.


When SPDTL = EDTL for a task, the target iSCSI layer completes
the task with no residuals.  Whenever SPDTL differs from EDTL
for a task, that task is said to have a residual.

If SPDTL > EDTL for a task, iSCSI Overflow MUST be signaled in
the SCSI Response PDU as specified in [RFC3720].  Residual Count
MUST be set to the numerical value of (SPDTL - EDTL).

If SPDTL < EDTL for a task, iSCSI Underflow MUST be signaled in
the SCSI Response PDU as specified in [RFC3720].  Residual Count
MUST be set to the numerical value of (EDTL - SPDTL).


Note that the Overflow and Underflow scenarios are independent
of Data-in and Data-out.  Either scenario is logically possible
in either direction of data transfer.












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3.1.2 SCSI REPORT LUNS and Residual Overflow

This section discusses the residual overflow issues citing the
example of SCSI REPORT LUNS command.  Note however that there
are several SCSI commands (e.g. INQUIRY) with ALLOCATION LENGTH
fields following the same underlying rules.  The semantics in
the rest of the section apply to all such SCSI commands.


The specification of the SCSI REPORT LUNS command requires that
the SCSI target limit the amount of data transferred to a
maximum size (ALLOCATION LENGTH) provided by the initiator in
the REPORT LUNS CDB.  If the Expected Data Transfer Length
(EDTL) in the iSCSI header of the SCSI Command PDU for a REPORT
LUNS command is set to at least as large as that ALLOCATION
LENGTH, the SCSI layer truncation prevents an iSCSI Residual
Overflow from occurring.  A SCSI initiator can detect that such
truncation has occurred via other information at the SCSI layer.
The rest of the section elaborates this required behavior.


iSCSI uses the (O) bit (bit 5) in the Flags field of the SCSI
Response and the last SCSI Data-In PDUs to indicate that that an
iSCSI target was unable to transfer all of the SCSI data for a
command to the initiator because the amount of data to be
transferred exceeded the EDTL in the corresponding SCSI Command
PDU (see Section 10.4.1 of [RFC3720]).


The SCSI REPORT LUNS command requests a target SCSI layer to
return a logical unit inventory (LUN list) to the initiator SCSI
layer (see section 6.21 of SPC-3 [SPC3]).  The size of this LUN
list may not be known to the initiator SCSI layer when it issues
the REPORT LUNS command; to avoid transfer of more LUN list data
than the initiator is prepared for, the REPORT LUNS CDB contains
an ALLOCATION LENGTH field to specify the maximum amount of data
to be transferred to the initiator for this command.  If the
initiator SCSI layer has under-estimated the number of logical
units at the target, it is possible that the complete logical
unit inventory does not fit in the specified ALLOCATION LENGTH.
In this situation, section 4.3.3.6 in [SPC3] requires that the
target SCSI layer "shall terminate transfers to the Data-In
Buffer" when the number of bytes specified by the ALLOCATION
LENGTH field have been transferred.







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Therefore, in response to a REPORT LUNS command, the SCSI layer
at the target presents at most ALLOCATION LENGTH bytes of data
(logical unit inventory) to iSCSI for transfer to the initiator.
For a REPORT LUNS command, if the iSCSI EDTL is at least as
large as the ALLOCATION LENGTH, the SCSI truncation ensures that
the EDTL will accommodate all of the data to be transferred.  If
all of the logical unit inventory data presented to the iSCSI
layer - i.e. the data remaining after any SCSI truncation - is
transferred to the initiator by the iSCSI layer, an iSCSI
Residual Overflow has not occurred and the iSCSI (O) bit MUST
NOT be set in the SCSI Response or final SCSI Data-Out PDU.
This is not a new requirement but is already required by the
combination of [RFC3720] with the specification of the REPORT
LUNS command in [SPC3]. If the iSCSI EDTL is larger than the
ALLOCATION LENGTH however in this scenario, note that the iSCSI
Underflow MUST be signaled in the SCSI Response PDU.  An iSCSI
Underflow MUST also be signaled when the iSCSI EDTL is equal to
ALLOCATION LENGTH but the logical unit inventory data presented
to the iSCSI layer is smaller than ALLOCATION LENGTH.


The LUN LIST LENGTH field in the logical unit inventory (first
field in the inventory) is not affected by truncation of the
inventory to fit in ALLOCATION LENGTH; this enables a SCSI
initiator to determine that the received inventory is incomplete
by noticing that the LUN LIST LENGTH in the inventory is larger
than the ALLOCATION LENGTH that was sent in the REPORT LUNS CDB.
A common initiator behavior in this situation is to re-issue the
REPORT LUNS command with a larger ALLOCATION LENGTH.

3.2 R2T Ordering

Section 10.8 in [RFC3720] says the following:

   The target may send several R2T PDUs. It, therefore, can have
   a number of pending data transfers. The number of outstanding
   R2T PDUs is limited by the value of the negotiated key
   MaxOutstandingR2T. Within a connection, outstanding R2Ts MUST
   be fulfilled by the initiator in the order in which they were
   received.

The quoted [RFC3720] text was unclear on the scope of
applicability - either per task, or across all tasks on a
connection - and may be interpreted as either.  This section is
intended to clarify that the scope of applicability of the
quoted text is a task.  No R2T ordering relationship - either in
generation at the target or in fulfilling at the initiator -
across tasks is implied.  I.e., outstanding R2Ts within a task





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MUST be fulfilled by the initiator in the order in which they
were received on a connection.


3.3 Model Assumptions for Response Ordering

Whenever an iSCSI session is composed of multiple connections,
the Response PDUs (task responses or TMF responses) originating
in the target SCSI layer are distributed onto the multiple
connections by the target iSCSI layer according to iSCSI
connection allegiance rules.  This process generally may not
preserve the ordering of the responses by the time they are
delivered to the initiator SCSI layer.  Since ordering is not
expected across SCSI responses anyway, this approach works fine
in the general case.  However to address the special cases where
some ordering is desired by the SCSI layer, the following
"Response Fence" semantics are defined with respect to handling
SCSI response messages as they are handed off from the SCSI
protocol layer to the iSCSI layer.

3.3.1 Model Description

Target SCSI protocol layer hands off the SCSI response messages
to the target iSCSI layer by invoking the "Send Command
Complete" protocol data service ([SAM2], clause 5.4.2) and "Task
Management Function Executed" ([SAM2], clause 6.9) service.   On
receiving the SCSI response message, iSCSI layer exhibits the
Response Fence behavior for certain SCSI response messages
(section 3.3.3 describes the specific instances where the
semantics must be realized). Whenever the Response Fence
behavior is required for a SCSI response message, the target
iSCSI layer MUST ensure that the following conditions are met in
delivering the response message to the initiator iSCSI layer:

  (1) Response with Response Fence MUST chronologically be
       delivered after all the "preceding" responses on the
       I_T_L nexus, if the preceding responses are delivered at
       all, to the initiator iSCSI layer.

  (2) Response with Response Fence MUST chronologically be
       delivered prior to all the "following" responses on the
       I_T_L nexus.

The "preceding" and "following" notions refer to the order of
hand-off of a response message from the target SCSI protocol
layer to the target iSCSI layer.







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3.3.2 iSCSI Semantics with the Interface Model

Whenever the TaskReporting key (section 9.1) is negotiated to
ResponseFence or FastAbort for an iSCSI session and the Response
Fence behavior is required for a SCSI response message, the
target iSCSI layer MUST perform the actions described in this
section for that session.:

  a) If it is a single-connection session, no special processing
     is required. Standard SCSI Response PDU build and dispatch
     process happens.

  b) If it is a multi-connection session, target iSCSI layer
     takes note of last-sent and unacknowledged StatSN on each
     of the connections in the iSCSI session, and waits for
     acknowledgement (Nop-In PDUs MAY be used to solicit
     acknowledgements as needed in order to accelerate this
     process) of each such StatSN to clear the fence. The SCSI
     response requiring Response Fence behavior MUST NOT be sent
     to the initiator before acknowledgements are received for
     each of the unacknowledged StatSNs..

  c) Target iSCSI layer must wait for an acknowledgement of the
     SCSI Response PDU that carried the SCSI response requiring
     the Response Fence behavior.  The fence MUST be considered
     cleared only after receiving the acknowledgement.

  d) All further status processing for the LU is resumed only
     after clearing the fence.  If any new responses for the
     I_T_L nexus are received from the SCSI layer before the
     fence is cleared, those Response PDUs MUST be held and
     queued at the iSCSI layer until the fence is cleared.

3.3.3 Current List of Fenced Response Use Cases

This section lists the fenced response use cases that iSCSI
implementations MUST comply with.  However, this is not an
exhaustive enumeration.  It is expected that as SCSI protocol
specifications evolve, the specifications will specify when
response fencing is required on a case-by-case basis.


Whenever the TaskReporting key (section 9.1) is negotiated to
ResponseFence or FastAbort for an iSCSI session, target iSCSI
layer MUST assume that Response Fence is required for the
following SCSI completion messages:





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  1. The first completion message carrying the UA after the
     multi-task abort on issuing and third-party sessions. See
     section 4.1.1 for related TMF discussion.

  2. The TMF Response carrying the multi-task TMF Response on
     the issuing session.

  3. The completion message indicating ACA establishment on the
     issuing session.

  4. The first completion message carrying the ACA ACTIVE status
     after ACA establishment on issuing and third-party
     sessions.

  5. The TMF Response carrying the Clear ACA response on the
     issuing session.

  6. The response to a PERSISTENT RESERVE OUT/PREEMPT AND ABORT
     command


Note: Due to the absence of ACA-related fencing requirements in
[RFC3720], initiator implementations SHOULD NOT use ACA on
multi-connection iSCSI sessions to targets complying only with
[RFC3720].  Initiators which want to employ ACA on multi-
connection iSCSI sessions SHOULD first assess response fencing
behavior via negotiating for ResponseFence or FastAbort values
for the TaskReporting (section 9.1) key.





















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4 Task Management

4.1 Requests Affecting Multiple Tasks

This section clarifies and updates the original text in section
10.6.2 of [RFC3720].  The clarified semantics (section 4.1.2)
are a superset of the protocol behavior required in the original
text and all iSCSI implementations MUST support the new
behavior. The updated semantics (section 4.1.3) on the other
hand are mandatory only when the new key TaskReporting (section
9.1) is negotiated to "FastAbort".

4.1.1 Scope of affected tasks

This section defines the notion of "affected tasks" in multi-
task abort scenarios.  Scope definitions in this section apply
to both the clarified protocol behavior (section 4.1.2) and the
updated protocol behavior (section 4.1.3).

    ABORT TASK SET: All outstanding tasks for the I_T_L nexus
     identified by the LUN field in the ABORT TASK SET TMF
     Request PDU.

    CLEAR TASK SET: All outstanding tasks in the task set for
     the LU identified by the LUN field in the CLEAR TASK SET
     TMF Request PDU.  See [SPC3] for the definition of a "task
     set".

    LOGICAL UNIT RESET: All outstanding tasks from all
     initiators for the LU identified by the LUN field in the
     LOGICAL UNIT RESET Request PDU.

    TARGET WARM RESET/TARGET COLD RESET: All outstanding tasks
     from all initiators across all LUs to which the TMF-issuing
     session has access to on the SCSI target device hosting the
     iSCSI session.

Usage: an "ABORT TASK SET TMF Request PDU" in the preceding text
is an iSCSI TMF Request PDU with the "Function" field set to
"ABORT TASK SET" as defined in [RFC3720].  Similar usage is
employed for other scope descriptions.

4.1.2 Clarified multi-task abort semantics

All iSCSI implementations MUST support the protocol behavior
defined in this section as the default behavior.  The execution
of ABORT TASK SET, CLEAR TASK SET, LOGICAL UNIT RESET, TARGET
WARM RESET, and TARGET COLD RESET TMF Requests consists of the
following sequence of actions in the specified order on the
specified party.




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The initiator iSCSI layer:

  a. MUST continue to respond to each TTT received for the
     affected tasks.

  b. SHOULD process any responses received for affected tasks in
     the normal fashion.  This is acceptable because the
     responses are guaranteed to have been sent prior to the TMF
     response.

  c. SHOULD receive the TMF Response concluding all the tasks in
     the set of affected tasks unless the initiator has done
     something (e.g.,LU reset, connection drop) that may prevent
     the TMF Response from being sent or received.  The
     initiator MUST thus conclude all affected tasks as part of
     this step in either case, and MUST discard any TMF Response
     received after the affected tasks are concluded.

The target iSCSI layer:

  a. MUST wait for responses on currently valid target transfer
     tags of the affected tasks from the issuing initiator. MAY
     wait for responses on currently valid target transfer tags
     of the affected tasks from third-party initiators.

  b. MUST wait (concurrent with the wait in Step.a) for all
     commands of the affected tasks to be received based on the
     CmdSN ordering.       SHOULD NOT wait for new commands on
     third-party affected sessions - only the instantiated tasks
     have to be considered for the purpose of determining the
     affected tasks.  In the case of target-scoped requests
     (i.e. TARGET WARM RESET and TARGET COLD RESET), all the
     commands that are not yet received on the issuing session
     in the command stream however can be considered to have
     been received with no command waiting period - i.e. the
     entire CmdSN space up to the CmdSN of the task management
     function can be "plugged".

  c. MUST propagate the TMF request to and receive the response
     from the target SCSI layer.

  d. MUST provide Response Fence behavior for the TMF Response
     on issuing session as specified in 3.3.2.

  e. MUST provide the Response Fence behavior on the first post-
     TMF Response on third-party sessions as specified in 3.3.2.
     If some tasks originate from non-iSCSI I_T_L nexuses then





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     the means by which the target ensures that all affected
     tasks have returned their status to the initiator are
     defined by the specific non-iSCSI transport protocol(s).

Technically, the TMF servicing is complete in Step.d.  Data
transfers corresponding to terminated tasks may however still be
in progress on third-party iSCSI sessions even at the end of
Step.e.  TMF Response MUST NOT be sent by the target iSCSI layer
before the end of Step.d, and MAY be sent at the end of Step.d
despite these outstanding data transfers until after Step.e.


4.1.3 Updated multi-task abort semantics

Protocol behavior defined in this section MUST be implemented by
all iSCSI implementations complying with this document.
Protocol behavior defined in this section MUST be exhibited by
iSCSI implementations on an iSCSI session when they negotiate
the TaskReporting (section 9.1) key to "FastAbort" on that
session.  The execution of ABORT TASK SET, CLEAR TASK SET,
LOGICAL UNIT RESET, TARGET WARM RESET, and TARGET COLD RESET TMF
Requests consists of the following sequence of actions in the
specified order on the specified party.

The initiator iSCSI layer:

  a. MUST NOT send any more Data-Out PDUs for affected tasks on
     the issuing connection of the issuing iSCSI session once
     the TMF is sent to the target.

  b. SHOULD process any responses received for affected tasks in
     the normal fashion.  This is acceptable because the
     responses are guaranteed to have been sent prior to the TMF
     response.

  c. MUST respond to each Async Message PDU with AsyncEvent=5 as
     defined in section 8.1.

  d. MUST treat the TMF response as terminating all affected
     tasks for which responses have not been received, and MUST
     discard any responses for affected tasks received after the
     TMF response is passed to the SCSI layer (although the
     semantics defined in this section ensure that such an out
     of order scenario will never happen with a compliant target
     implementation).





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The target iSCSI layer:

  a. MUST wait for all commands of the affected tasks to be
     received based on the CmdSN ordering on the issuing
     session.  SHOULD NOT wait for new commands on third-party
     affected sessions - only the instantiated tasks have to be
     considered for the purpose of determining the affected
     tasks.  In the case of target-scoped requests (i.e. TARGET
     WARM RESET and TARGET COLD RESET), all the commands that
     are not yet received on the issuing session in the command
     stream can be considered to have been received with no
     command waiting period - i.e. the entire CmdSN space up to
     the CmdSN of the task management function can be "plugged".

  b. MUST propagate the TMF request to and receive the response
     from the target SCSI layer.

  c. MUST leave all active "affected TTTs" (i.e. active TTTs
     associated with affected tasks) valid.

  d. MUST send an Asynchronous Message PDU with AsyncEvent=5
     (section 8.1) on:
     i) each connection of each third-party session to which at
       least one affected task is allegiant if
       TaskReporting=FastAbort is operational on that third-
       party session, and
     ii)each connection except the issuing connection of the
       issuing session that has at least one allegiant affected
       task.

     If there are multiple affected LUs (say due to a target
     reset), then one Async Message PDU MUST be sent for each
     such LU on each connection that has at least one allegiant
     affected task.  The LUN field in the Asynchronous Message
     PDU MUST be set to match the LUN for each such LU.

  e. MUST address the Response Fence flag on the TMF Response on
     issuing session as defined in 3.3.2.

  f. MUST address the Response Fence flag on the first post-TMF
     Response on third-party sessions as defined in 3.3.2. If
     some tasks originate from non-iSCSI I_T_L nexuses then the





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     means by which the target ensures that all affected tasks
     have returned their status to the initiator are defined by
     the specific non-iSCSI transport protocol(s).

  g. MUST free up the affected TTTs (and STags, if applicable)
     and the corresponding buffers, if any, once it receives
     each associated Nop-Out acknowledgement that the initiator
     generated in response to each Async Message.

Technically, the TMF servicing is complete in Step.e.  Data
transfers corresponding to terminated tasks may however still be
in progress even at the end of Step.f.  TMF Response MUST NOT be
sent by the target iSCSI layer before the end of Step.e, and MAY
be sent at the end of Step.e despite these outstanding Data
transfers until Step.g.  Step.g specifies an event to free up
any such resources that may have been reserved to support
outstanding data transfers.

4.1.3.1 Clearing effects update

Appendix F.1 of [RFC3720] specifies the clearing effects of
target and LU resets on "Incomplete TTTs" as "Y".  This meant
that a target warm reset or a target cold reset or an LU reset
would clear the active TTTs upon completion.  The
TaskReporting=FastAbort (section 9.1) semantics defined by this
section however do not guarantee that the active TTTs are
cleared by the end of the reset operations.  In fact, the new
semantics are designed to allow clearing the TTTs in a "lazy"
fashion after the TMF Response is delivered.  Thus, when
TaskReporting=FastAbort is operational on a session, the
clearing effects of reset operations on "Incomplete TTTs" is
"N".

4.1.4 Affected tasks shared across RFC3720 & FastAbort sessions

If an iSCSI target implementation is capable of supporting
TaskReporting=FastAbort functionality (section 9.1), it may end
up in a situation where some sessions have TaskReporting=RFC3720
operational (RFC3720 sessions) while some other sessions have
TaskReporting=FastAbort operational (FastAbort sessions) even
while accessing a shared set of affected tasks (section 4.1.1).








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If the issuing session is a RFC3720 session, iSCSI target
implementation is FastAbort-capable and third-party affected
session is a FastAbort session, the following behavior SHOULD be
exhibited by the iSCSI target layer:

  a. Between steps c and d of target behavior in section 4.1.2,
     send an Asynchronous Message PDU with AsyncEvent=5 (section
     8.1) on each connection of each third-party session to
     which at least one affected task is allegiant.  If there
     are multiple affected LUs, then send one Async Message PDU
     for each such LU on each connection that has at least one
     allegiant affected task.  When sent, the LUN field in the
     Asynchronous Message PDU MUST be set to match the LUN for
     each such LU.
  b. After step e of target behavior in section 4.1.2, free up
     the affected TTTs (and STags, if applicable) and the
     corresponding buffers, if any, once each associated Nop-Out
     acknowledgement is received that the third-party initiator
     generated in response to each Async Message sent in step a.

If the issuing session is a FastAbort session, iSCSI target
implementation is FastAbort-capable and third-party affected
session is a RFC3720 session, the following behavior MUST be
exhibited by the iSCSI target layer: Asynchronous Message PDUs
MUST NOT be sent on the third-party session to prompt the
FastAbort behavior.

If the third-party affected session is a FastAbort session and
issuing session is a FastAbort session, initiator in the third-
party role MUST respond to each Async Message PDU with
AsyncEvent=5 as defined in section 8.1.  Note that an initiator
MAY thus receive these Async Messages on a third-party affected
session even if the session is a single-connection session.

4.1.5 Implementation considerations

Both in clarified semantics (section 4.1.2) and updated
semantics (section 4.1.3), there may be outstanding data
transfers even after the TMF completion is reported on the
issuing session.  In the case of iSCSI/iSER [iSER], these would
be tagged data transfers for STags not owned by any active
tasks. Whether or not real buffers support these data transfers
is implementation-dependent.  However, the data transfers
logically MUST be silently discarded by the target iSCSI layer





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in all cases.  A target MAY, on an implementation-defined
internal timeout, also choose to drop the connections on which
it did not receive the expected Data-out sequences (section
4.1.2) or Nop-Out acknowledgements (section 4.1.3) so as to
reclaim the associated buffer, STag and TTT resources as
appropriate.

4.1.6 Rationale behind the new semantics

There are fundamentally three basic objectives behind the
semantics specified in section 4.1.2 and section 4.1.3.

   1. Maintaining an ordered command flow I_T nexus abstraction
      to the target SCSI layer even with multi-connection
      sessions.

       o Target iSCSI processing of a TMF request must maintain
          the single flow illusion.  Target behavior in Step.b
          of section 4.1.2 and Step.a of section 4.1.3
          correspond to this objective.

   2. Maintaining a single ordered response flow I_T nexus
      abstraction to the initiator SCSI layer even with multi-
      connection sessions when one response (i.e. TMF response)
      could imply the status of other unfinished tasks from the
      initiator's perspective.

       o Target must ensure that the initiator does not see
          "old" task responses (that were placed on the wire
          chronologically earlier than the TMF Response) after
          seeing the TMF response. Target behavior in Step.d of
          section 4.1.2 and Step.e of section 4.1.3 correspond
          to this objective.

       o Whenever the result of a TMF action is visible across
          multiple I_T_L nexuses, [SAM2] requires the SCSI
          device server to trigger a UA on each of the other
          I_T_L nexuses. Once an initiator is notified of such
          an UA, the application client on the receiving
          initiator is required to clear its task state (clause
          5.5 in [SAM2]) for the affected tasks. It would thus
          be inappropriate to deliver a SCSI Response for a task
          after the task state is cleared on the initiator, i.e.
          after the UA is notified.  The UA notification
          contained in the first SCSI Response PDU on each
          affected Third-party I_T_L nexus after the TMF action
          thus MUST NOT pass the affected task responses on any
          of the iSCSI sessions accessing the LU. Target





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          behavior in Step.e of section 4.1.2 and Step.f of
          section 4.1.3 correspond to this objective.

   3. Draining all active TTTs corresponding to affected tasks
      in a deterministic fashion.

       o Data-out PDUs with stale TTTs arriving after the tasks
          are terminated can create a buffer management problem
          even for traditional iSCSI implementations, and is
          fatal for the connection for iSCSI/iSER
          implementations.  Either the termination of affected
          tasks should be postponed until the TTTs are retired
          (as in Step.a of section 4.1.2), or the TTTs and the
          buffers should stay allocated beyond task termination
          to be deterministically freed up later (as in Step.c
          and Step.g of section 4.1.3).


The only other notable optimization is the plugging.  If all
tasks on an I_T nexus will be aborted anyway (as with a target
reset), there is no need to wait to receive all commands to plug
the CmdSN holes.  Target iSCSI layer can simply plug all missing
CmdSN slots and move on with TMF processing.  The first
objective (maintaining a single ordered command flow) is still
met with this optimization because target SCSI layer only sees
ordered commands.





















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5 Discovery semantics

5.1 Error Recovery for Discovery Sessions

The negotiation of the key ErrorRecoveryLevel is not required
for Discovery sessions - i.e. for sessions that negotiated
"SessionType=Discovery" - because the default value of 0 is
necessary and sufficient for Discovery sessions.  It is however
possible that some legacy iSCSI implementations might attempt to
negotiate the ErrorRecoveryLevel key on Discovery sessions.
When such a negotiation attempt is made by the remote side, a
compliant iSCSI implementation MUST propose a value of 0 (zero)
in response.  The operational ErrorRecoveryLevel for Discovery
sessions thus MUST be 0.  This naturally follows from the
functionality constraints [RFC3720] imposes on Discovery
sessions.


5.2 Reinstatement Semantics of Discovery Sessions

Discovery sessions are intended to be relatively short-lived.
Initiators are not expected to establish multiple Discovery
sessions to the same iSCSI Network Portal (see [RFC3720]).  An
initiator may use the same iSCSI Initiator Name and ISID when
establishing different unique sessions with different targets
and/or different portal groups.  This behavior is discussed in
Section 9.1.1 of [RFC3720] and is, in fact, encouraged as
conservative reuse of ISIDs.  ISID RULE in [RFC3720] states that
there must not be more than one session with a matching 4-tuple:
<InitiatorName, ISID, TargetName, TargetPortalGroupTag>.  While
the spirit of the ISID RULE applies to Discovery sessions the
same as it does for Normal sessions, note that some Discovery
sessions differ from the Normal sessions in two important
aspects:

    Because [RFC3720] allows a Discovery session to be
     established without specifying a TargetName key in the
     Login Request PDU (let us call such a session an "Unnamed"
     Discovery session), there is no Target Node context to
     enforce the ISID RULE.

    Portal Groups are defined only in the context of a Target
     Node.  When the TargetName key is NULL-valued (i.e. not
     specified), the TargetPortalGroupTag thus cannot be
     ascertained to enforce the ISID RULE.







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The following sections describe the two scenarios - Named
Discovery sessions and Unnamed Discovery sessions - separately.


5.2.1 Unnamed Discovery Sessions

For Unnamed Discovery sessions, neither the TargetName nor the
TargetPortalGroupTag is available to the targets in order to
enforce the ISID RULE.  So the following rule applies.


UNNAMED ISID RULE: Targets MUST enforce the uniqueness of the
following 4-tuple for Unnamed Discovery sessions:
<InitiatorName, ISID, NULL, TargetAddress>.  The following
semantics are implied by this uniqueness requirement.


Targets SHOULD allow concurrent establishment of one Discovery
session with each of its Network Portals by the same initiator
port with a given iSCSI Node Name and an ISID. Each of the
concurrent Discovery sessions, if established by the same
initiator port to other Network Portals, MUST be treated as
independent sessions - i.e. one session MUST NOT reinstate the
other.


A new Unnamed Discovery session that has a matching
<InitiatorName, ISID, NULL, TargetAddress> to an existing
discovery session MUST reinstate the existing Unnamed Discovery
session. Note thus that only an Unnamed Discovery session may
reinstate an Unnamed Discovery session.


5.2.2 Named Discovery Sessions

For a Named Discovery session, the TargetName key is specified
by the initiator and thus the target can unambiguously ascertain
the TargetPortalGroupTag as well.  Since all the four elements
of the 4-tuple are known, the ISID RULE MUST be enforced by
targets with no changes from [RFC3720] semantics.  A new session
with a matching <InitiatorName, ISID, TargetName,
TargetPortalGroupTag> thus will reinstate an existing session.
Note in this case that any new iSCSI session (Discovery or
Normal) with the matching 4-tuple may reinstate an existing
Named Discovery iSCSI session.




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5.3 Target PDUs during Discovery

Targets SHOULD NOT send any responses other than a Text Response
and Logout Response on a Discovery session, once in full feature
phase.

Implementation Note: A target may simply drop the connection in
a Discovery session when it would have requested a Logout via an
Async Message on Normal sessions.




































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6 Negotiation and Others

6.1 TPGT Values

[SAM2] and [SAM3] specifications incorrectly note in their
informative text that TPGT value should be non-zero, although
[RFC3720] allows the value of zero for TPGT.  This section is to
clarify that zero value is expressly allowed as a legal value
for TPGT.  This discrepancy currently stands corrected in
[SAM4].


6.2 SessionType Negotiation

During the Login phase, the SessionType key is offered by the
initiator to choose the type of session it wants to create with
the target.  The target may accept or reject the offer.
Depending on the type of the session, a target may decide on
resources to allocate and the security to enforce etc. for the
session.  If the SessionType key is thus going to be offered as
"Discovery", it SHOULD be offered in the initial Login request
by the initiator.


6.3 Understanding NotUnderstood

[RFC3720] defines NotUnderstood as a valid answer during a
negotiation text key exchange between two iSCSI nodes.
NotUnderstood has the reserved meaning that the sending side did
not understand the proposed key semantics.  This section seeks
to clarify that NotUnderstood is a valid answer for both
declarative and negotiated keys.  The general iSCSI philosophy
is that comprehension precedes processing for any iSCSI key.  A
proposer of an iSCSI key, negotiated or declarative, in a text
key exchange MUST thus be able to properly handle a
NotUnderstood response.


The proper way to handle a NotUnderstood response depends on
where the key is specified and whether the key is declarative
vs. negotiated. All keys defined in [RFC3720] MUST be supported
by all compliant implementations; a NotUnderstood answer on any
of the [RFC3720] keys therefore MUST be considered a protocol
error and handled accordingly.  For all other later keys, a
NotUnderstood answer concludes the negotiation for a negotiated
key whereas for a declarative key, a NotUnderstood answer simply
informs the declarer of lack of comprehension by the receiver.




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In either case, a NotUnderstood answer always requires that the
protocol behavior associated with that key be not used within
the scope of the key (connection/session) by either side.

6.4 Outstanding Negotiation Exchanges

There was some uncertainty around the number of outstanding
Login Response PDUs on a connection.  [RFC3720] offers the
analogy of SCSI linked commands to Login and Text negotiations
in sections 5.3 and 10.10.3 respectively, but does not make it
fully explicit.  This section is to offer a clarification in
this regard.


There MUST NOT be more than one outstanding Login Request or
Login Response or Text Request or Text Response PDU on an iSCSI
connection.  An outstanding PDU in this context is one that has
not been acknowledged by the remote iSCSI side.




























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7 iSCSI Error Handling and Recovery

7.1 ITT

Section 10.19 in [RFC3720] mentions this in passing but noted
here again for making it obvious since the semantics apply to
the initiators in general.  An ITT value of 0xffffffff is
reserved and MUST NOT be assigned for a task by the initiator.
The only instance it may be seen on the wire is in a target-
initiated NOP-In PDU (and in the initiator response to that PDU
if necessary).


7.2 Format Errors

Section 6.6 of [RFC3720] discusses format error handling.  This
section elaborates on the "inconsistent" PDU field contents
noted in [RFC3720].

All initiator-detected PDU construction errors MUST be
considered as format errors.  Some examples of such errors are:

- NOP-In with a valid TTT but an invalid LUN

- NOP-In with a valid ITT (i.e. a NOP-In response) and also a
valid TTT

- SCSI Response PDU with Status=CHECK CONDITION, but
DataSegmentLength = 0


7.3 Digest Errors

Section 6.7 of [RFC3720] discusses digest error handling.  It
states that "No further action is necessary for initiators if
the discarded PDU is an unsolicited PDU (e.g., Async, Reject)"
on detecting a payload digest error.  This is incorrect.


An Asynchronous Message PDU or a Reject PDU carries the next
StatSN value on an iSCSI connection, advancing the StatSN.  When
an initiator discards one of these PDUs due to a payload digest
error, the entire PDU including the header MUST be discarded.
Consequently, the initiator MUST treat the exception like a loss
of any other solicited response PDU - i.e. it MUST use one of
the following options noted in [RFC3720]:





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    a)    Request PDU retransmission with a status SNACK.

    b)    Logout the connection for recovery and continue the
          tasks on a different connection instance.

    c)    Logout to close the connection (abort all the commands
          associated with the connection).


7.4 Message Error Checking

There has been some uncertainty on the extent to which incoming
messages have to be checked for protocol errors, beyond what is
strictly required for processing the inbound message.  This
section addresses that question.

Unless [RFC3720] or this draft requires it, an iSCSI
implementation is not required to do an exhaustive protocol
conformance checking on an incoming iSCSI PDU.  The iSCSI
implementation especially is not required to double-check the
remote iSCSI implementation's conformance to protocol
requirements.























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8 iSCSI PDUs

8.1 Asynchronous Message

This section defines additional semantics for the Asynchronous
Message PDU defined in section 10.9 of [RFC3720] using the same
conventions.

The following new legal value for AsyncEvent is defined:

5: all active tasks for LU with matching LUN field in the Async
Message PDU are being terminated.

The receiving initiator iSCSI layer MUST respond to this Message
by taking the following steps in order.

     i) Stop Data-Out transfers on that connection for all active
       TTTs for the affected LUN quoted in the Async Message
       PDU.
     ii)Acknowledge the StatSN of the Async Message PDU via a
       Nop-Out PDU with ITT=0xffffffff (i.e. non-ping flavor),
       while copying the LUN field from Async Message to Nop-
       Out.

The new AsyncEvent defined in this section however MUST NOT be
used on an iSCSI session unless the new TaskReporting text key
defined in section 9.1 was negotiated to FastAbort on the
session.

8.2 Reject

Section 10.17.1 of [RFC3720] specifies the Reject reason code of
0x0b with an explanation of "Negotiation Reset".  At this point,
we do not see any legitimate iSCSI protocol use case for using
this reason code.  Thus reason code 0x0b MUST be considered as
deprecated and MUST NOT be sent by implementations that
comply with the requirements of this document.  An
implementation receiving reason code 0x0b MUST treat it as a
negotiation failure that terminates the Login phase and the TCP
connection, as specified in Section 6.10 of [RFC3720].

Section 5.4 of [RFC3720] states:

    Neither the initiator nor the target should attempt to
    declare or negotiate a parameter more than once during any
    negotiation sequence without an intervening operational
    parameter negotiation reset, except for responses to




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    specific keys that explicitly allow repeated key
    declarations (e.g., TargetAddress).

The deprecation of reason code 0x0b eliminates the possibility
of an operational parameter negotiation reset, causing
the phrase "without an intervening operational
parameter negotiation reset" in [RFC3720] to refer to an
impossible event. The quoted phrase SHOULD be ignored by
receivers that handle reason code 0x0b in the manner specified
in this section.


































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9 Login/Text Operational Text Keys

This section follows the same conventions as section 12 of
[RFC3720].

9.1 TaskReporting

Use: LO
Senders: Initiator and Target
Scope: SW

Irrelevant when: SessionType=Discovery
TaskReporting=<list-of-values>

Default is RFC3720.
Result function is AND.

This key is used to negotiate the task completion reporting
semantics from the SCSI target. Following table describes the
semantics an iSCSI target MUST support for respective negotiated
key values.  Whenever this key is negotiated, at least the
RFC3720 and ResponseFence values MUST be offered as options by
the negotiation originator.

+--------------+------------------------------------------+
| Name         |             Description                  |
+--------------+------------------------------------------+
| RFC3720         | RFC 3720-compliant semantics.  Response |
|              | fencing is not guaranteed and fast     |
|              | completion of multi-task aborting is not |
|              | supported                                |
+--------------+------------------------------------------+
| ResponseFence| Response Fence (section 3.3.1) semantics |
|              | MUST be supported in reporting task      |
|              | completions                              |
+--------------+------------------------------------------+
| FastAbort    | Updated fast multi-task abort semantics  |
|              | defined in section 4.1.3 MUST be        |
|              | supported.  Support for Response Fence is|
|              | implied - i.e. section 3.3.1 semantics   |
|              | MUST be supported as well                |
+--------------+------------------------------------------+







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When TaskReporting is not negotiated to FastAbort, the [RFC3720]
TMF semantics as clarified in section 4.1.2 MUST be used.









































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10 Security Considerations

This document does not introduce any new security considerations
other than those already noted in [RFC3720].   Consequently, all
the iSCSI-related security text in [RFC3723] is also directly
applicable to this document.






































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11 IANA Considerations

11.1 iSCSI-related IANA registries

This draft creates the following iSCSI-related registries for
IANA to manage.

  1. iSCSI Opcodes

  2. iSCSI Login/Text Keys

  3. iSCSI Asynchronous Events

  4. iSCSI Task Management Function Codes

  5. iSCSI Login Response Status Codes

  6. iSCSI Reject Reason Codes

  7. iSER Opcodes

Each of the following sections describes a proposed registry and
its sub-registries if any and their administration policies in
more detail. IANA may publish what this document calls the main
"registries" as sub-registries of a larger iSCSI registry if
doing so is appropriate.  However, wherever registry-to-sub-
registry relationships are specified by this document, they must
be preserved intact in the new hierarchy by the end of the IANA
publication process.


[RFC3720] specifies three iSCSI-related registries - extended
key, authentication methods, digests.  This document recommends
that those registries be published together with the registries
defined by this document.  Further, this document recommends
that the three [RFC3720] registries be listed in between
registry item no. 6 and registry item no. 7 in the registry list
that preceded this text.

11.2 iSCSI Opcodes

Name of the registry: "iSCSI Opcodes"


Namespace details: Numerical values that can fit in one octet
with most significant two bits (bits 0 and 1) already designated
by [RFC3720], bit 0 being reserved and bit 1 for immediate





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delivery.  Bit 2 is designated to identify the originator of the
opcode.  Bit 2 = 0 for initiator and Bit 2 = 1 for target


Information that must be provided to assign a new value: An
IESG-approved standards-track specification defining the
semantics and interoperability requirements of the proposed new
value and the fields to be recorded in the registry


Allocation request guidance to requesters:

1) If initiator opcode and target opcode to identify the request
and response of a new type of protocol operation are requested,
assign the same lower five bits (i.e. Bit 3 through Bit 7) for
both opcodes, e.g. 0x13 and 0x33

2) If only the initiator opcode or target opcode is requested to
identify a one-way protocol message (i.e. request without a
response or a "response" without a request), assign an unused
number from the appropriate category (i.e. Bit 2 set to 0 or 1
for initiator category or target category) and add the other
pair member (i.e. same opcode with Bit 2 set to 1 or 0,
respectively) to "Reserved to IANA" list.

3) If there are no other opcodes available to assign on a
request for a new opcode except the reserved opcodes in the
"Reserved to IANA" list, allocate the opcodes from the
appropriate category (initiator or target).


Notes to IANA:

- Publish the preceding Allocation request guidance verbatim in
the registry

- Use the Expert Review process ([IANA]) to ensure that
compliance with the Allocation request guidance is met


Fields to record in the registry: Assigned value, Who can
originate (Initiator or Target), Operation Name and its
associated RFC reference







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Initial registry contents:

0x00, Initiator, NOP-Out, [RFC3720]

0x01, Initiator, SCSI Command, [RFC3720]

0x02, Initiator, SCSI Task Management function request,
[RFC3720]

0x03, Initiator, Login Request, [RFC3720]

0x04, Initiator, Text Request, [RFC3720]

0x05, Initiator, SCSI Data-Out, [RFC3720]

0x06, Initiator, Logout Request, [RFC3720]

0x10, Initiator, SNACK Request, [RFC3720]

0x1c-0x1e, Initiator, Vendor specific codes, [RFC3720]

0x20, Target, NOP-In, [RFC3720]

0x21, Target, SCSI Response, [RFC3720]

0x22, Target, SCSI Task Management function response, [RFC3720]

0x23, Target, Login Response, [RFC3720]

0x24, Target, Text Response, [RFC3720]

0x25, Target, SCSI Data-In, [RFC3720]

0x26, Target, Logout Response, [RFC3720]

0x31, Target, Ready To Transfer (R2T), [RFC3720]

0x32, Target, Asynchronous Message, [RFC3720]

0x3c-0x3e, Target, Vendor specific codes, [RFC3720]

0x3f, Target, Reject, [RFC3720]

"Reserved to IANA" opcodes: 0x11, 0x12, 0x1f, 0x30

Allocation Policy:

Standards Action ([IANA]): This is required for defining the
semantics of the opcode





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Expert Review ([IANA]): This is required for selecting the
specific opcode(s) to allocate in order to ensure compliance
with the earlier "Allocation request guidance to requesters"


11.3 iSCSI Login/Text Keys

Name of the registry: "iSCSI Text Keys"


Namespace details: Key=value pairs with "Key" names in UTF-8
Unicode, and the permissible "value" options for the "Key" are
Key-dependent.  [RFC3720] defines the rules on key names and
allowed values


Information that must be provided to assign a new value: An
IESG-approved standards-track specification defining the
semantics and interoperability requirements of the proposed new
Key per [RFC3720] key specification template and the fields to
be recorded in the registry


Assignment policy:

If the requested Key name is not already assigned and is roughly
representative of its proposed semantics, it may be assigned to
the requester.


Given the arbitrary nature of text strings, there is no maximum
reserved by IANA for assignment in this registry.


Fields to record in the registry: Assigned Key Name and its
associated RFC reference


Initial registry contents:

AuthMethod, [RFC3720]




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HeaderDigest, [RFC3720]

DataDigest, [RFC3720]

MaxConnections, [RFC3720]

SendTargets, [RFC3720]

TargetName, [RFC3720]

InitiatorName, [RFC3720]

TargetAlias, [RFC3720]

InitiatorAlias, [RFC3720]

TargetAddress, [RFC3720]

TargetPortalGroupTag, [RFC3720]

InitialR2T, [RFC3720]

ImmediateData, [RFC3720]

MaxRecvDataSegmentLength, [RFC3720]

MaxBurstLength, [RFC3720]

FirstBurstLength, [RFC3720]

DefaultTime2Wait, [RFC3720]

DefaultTime2Retain, [RFC3720]

MaxOutstandingR2T, [RFC3720]

DataPDUInOrder, [RFC3720]

DataSequenceInOrder, [RFC3720]

ErrorRecoveryLevel, [RFC3720]

SessionType, [RFC3720]

RDMAExtensions, [iSER]

TargetRecvDataSegmentLength, [iSER]

InitiatorRecvDataSegmentLength, [iSER]





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MaxOutstandingUnexpectedPDUs, [iSER]

TaskReporting, this document


Allocation Policy:

Standards Action ([IANA])


11.4 iSCSI Asynchronous Events

Name of the registry: "iSCSI Asynchronous Events"


Namespace details: Numerical values that can fit in one octet


Information that must be provided to assign a new value: A IESG-
approved standards-track specification defining the semantics
and interoperability requirements of the proposed new Event and
the fields to be recorded in the registry


Assignment policy:

If the requested value is not already assigned, it may be
assigned to the requester.


6-247: range reserved by IANA for assignment in this registry


Fields to record in the registry: Assigned Event number,
Description and its associated RFC reference


Initial registry contents:

0, SCSI Async Event, [RFC3720]

1, Logout Request, [RFC3720]




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2, Connection drop notification, [RFC3720]

3, Session drop notification, [RFC3720]

4, Negotiation Request, [RFC3720]

5, Task termination, this document

248-254, Vendor-unique, this document

255, Vendor-unique, [RFC3720]


Allocation Policy:

Standards Action ([IANA])


11.5 iSCSI Task Management Function Codes

Name of the registry: "iSCSI TMF Codes"

Namespace details: Numerical values that can fit in 7 bits

Information that must be provided to assign a new value: An
IESG-approved standards-track specification defining the
semantics and interoperability requirements of the proposed new
Code and the fields to be recorded in the registry

Assignment policy:

If the requested value is not already assigned, it may be
assigned to the requester.

9-127: range reserved by IANA for assignment in this registry


Fields to record in the registry: Assigned Code, Description and
its associated RFC reference

Initial registry contents:

1, ABORT TASK, [RFC3720]

2, ABORT TASK SET, [RFC3720]

3, CLEAR ACA, [RFC3720]




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4, CLEAR TASK SET, [RFC3720]

5, LOGICAL UNIT RESET, [RFC3720]

6, TARGET WARM RESET, [RFC3720]

7, TARGET COLD RESET, [RFC3720]

8, TASK REASSIGN, [RFC3720]

Allocation Policy:

Standards Action ([IANA])


11.6 iSCSI Login Response Status Codes

Name of the registry: "iSCSI Login Response Status Codes"


Namespace details: Numerical values; Status-Class (one octet),
Status-Detail (one octet) for each possible value of Status-
Class except for Vendor-Unique Status-Class (0x0f)


Information that must be provided to assign a new value: An
IESG-approved specification defining the semantics and
interoperability requirements of the proposed new Code, its
Status-Class affiliation (only if a new Status-Detail value is
being proposed for a Status-Class), Status-Class definition
(only if a new Status-Class is being proposed) and the fields to
be recorded in the registry


Assignment policy:

If the requested value is not already assigned, it may be
assigned to the requester.

4-14 and 16-255: range reserved by IANA for assignment in this
registry


Fields to record in the Status-Class main registry: Assigned
Code, Description and its associated RFC reference




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Fields to record in the Status-Detail sub-registries: Status-
Class, Assigned Code, Description and its associated RFC
reference


Initial registry contents (Status-Class):

0x00, Success, [RFC3720]

0x01, Redirection, [RFC3720]

0x02, Initiator Error, [RFC3720]

0x03, Target Error, [RFC3720]

0x0f, Vendor-Unique, this document


Initial sub-registry contents (Status-Detail for Status-
Class=0x00):

0x00, 0x00, Success, [RFC3720]

1-255: range reserved by IANA for assignment in Status-Class=0
sub-registry


Initial sub-registry contents (Status-Detail for Status-
Class=0x01):

0x01, 0x01, Temporary move, [RFC3720]

0x01, 0x02, Permanent move, [RFC3720]

3-255: range reserved by IANA for assignment in Status-Class=1
sub-registry


Initial sub-registry contents (Status-Detail for Status-
Class=0x02):

0x02, 0x00, Miscellaneous, [RFC3720]

0x02, 0x01, Authentication failure, [RFC3720]

0x02, 0x02, Authorization failure, [RFC3720]




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0x02, 0x03, Not found, [RFC3720]

0x02, 0x04, Target removed, [RFC3720]

0x02, 0x05, Unsupported version, [RFC3720]

0x02, 0x06, Too many connections, [RFC3720]

0x02, 0x07, Missing parameter, [RFC3720]

0x02, 0x08, Can't include in session, [RFC3720]

0x02, 0x09, Unsupported session type, [RFC3720]

0x02, 0x0a, Non-existent session, [RFC3720]

0x02, 0x0b, Invalid during login, [RFC3720]

12-255: range reserved by IANA for assignment in Status-Class=2
sub-registry


Initial sub-registry contents (Status-Detail for Status-
Class=0x03):

0x03, 0x00, Target error, [RFC3720]

0x03, 0x01, Service unavailable, [RFC3720]

0x03, 0x02, Out of resources, [RFC3720]

3-255: range reserved by IANA for assignment in Status-Class=3
sub-registry


Allocation Policy:

Standards Action ([IANA])


11.7 iSCSI Reject Reason Codes

Name of the registry: "iSCSI Reject Reason Codes"







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Namespace details: Numerical values that can fit in a single
octet


Information that must be provided to assign a new value: A
published specification defining the semantics and
interoperability requirements of the proposed new Code and the
fields to be recorded in the registry


Assignment policy:

If the requested value is not already assigned, it may be
assigned to the requester.

13-255: range reserved by IANA for assignment in this registry


Fields to record in the registry: Assigned Code, Description and
its associated RFC reference


Initial registry contents:

0x01, Reserved, [RFC3720]

0x02, Data digest error, [RFC3720]

0x03, SNACK Reject, [RFC3720]

0x04, Protocol Error, [RFC3720]

0x05, Command not supported, [RFC3720]

0x06, Immediate command reject, [RFC3720]

0x07, Task in progress, [RFC3720]

0x08, Invalid data ack, [RFC3720]

0x09, Invalid PDU field, [RFC3720]

0x0a, Long op reject, [RFC3720]

0x0b, "Deprecated reason code", this document





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0x0c, Waiting for Logout, [RFC3720]


Allocation Policy:

Standards Action ([IANA])


11.8 iSER Opcodes

Name of the registry: "iSER Opcodes"


Namespace details: Numerical values that can fit in 4 bits


Information that must be provided to assign a new value: An
IESG-approved specification defining the semantics and
interoperability requirements of the proposed new value and the
fields to be recorded in the registry


Assignment policy:

If the requested value is not already assigned, it may be
assigned to the requester.

4-15: range reserved by IANA for assignment in this registry


Fields to record in the registry: Assigned value, Operation Name
and its associated RFC reference


Initial registry contents:

0x1, iSCSI control-type, [iSER]

0x2, iSER Hello, [iSER]

0x3, iSER HelloReply, [iSER]






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Allocation Policy:

Standards Action ([IANA])









































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12 References and Bibliography

12.1 Normative References

   [RFC3720] Satran, J., Meth, K., Sapuntzakis, C., Chadalapaka,
          M., and E. Zeidner, "Internet Small Computer Systems
          Interface (iSCSI)", RFC 3720, April 2004.

   [SPC3] ANSI INCITS 408-2005, SCSI Primary Commands-3.

   [RFC2119] S. Bradner, "Key words for use in RFCs to Indicate
   Requirement Levels", March 1997.

   [IANA] Alvestrand, H. and T. Narten, "Guidelines for Writing
   an IANA Considerations Section in RFCs", BCP 26, RFC 2434,
   October 1998.

   [iSER] Ko, M., Chadalapaka, M., Elzur, U., Shah, H., Thaler,
   P., J. Hufferd, "iSCSI Extensions for RDMA", IETF Internet
   Draft draft-ietf-ips-iser-04.txt (work in progress),  June
   2005.


12.2 Informative References

   [RFC3721] Bakke, M., Hafner, J., Hufferd, J., Voruganti, K.,
   and M. Krueger, "Internet Small Computer Systems Interface
   (iSCSI) Naming and Discovery", RFC 3721, April 2004.

   [RFC3723] Aboba, B., Tseng, J., Walker, J., Rangan, V., and
   F. Travostino, "Securing Block Storage Protocols over IP",
   RFC 3723, April 2004.

   [RFC3722] Bakke, M., "String Profile for Internet Small
          Computer Systems Interface (iSCSI) Names", RFC 3722, April
          2004.

   [SAM2] ANSI INCITS 366-2003, SCSI Architecture Model-2 (SAM-
   2).

   [SAM3] ANSI INCITS 402-2005, SCSI Architecture Model-3 (SAM-
   3).

   [SAM4] T10 Project: 1683-D, SCSI Architecture Model-4 (SAM-
   4), Work in Progress.







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13 Editor's Address

   Mallikarjun Chadalapaka
   Hewlett-Packard Company
   8000 Foothills Blvd.
   Roseville, CA 95747-5668, USA
   Phone: +1-916-785-5621
   E-mail: cbm@rose.hp.com





































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14 Acknowledgements

   The IP Storage (ips) Working Group in the Transport Area of
   IETF has been responsible for defining the iSCSI protocol
   (apart from a host of other relevant IP Storage protocols).
   The editor acknowledges the contributions of the entire
   working group.

   The following individuals directly contributed to identifying
   [RFC3720] issues and/or suggesting resolutions to the issues
   clarified in this document: David Black, Gwendal Grignou,
   Mike Ko, Dmitry Fomichev, Bill Studenmund, Ken Sandars, Bob
   Russell, Julian Satran, Rob Elliott, Joseph Pittman, Somesh
   Gupta, Eddy Quicksall, Paul Koning. This document benefited
   from all these contributions.































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15 Full Copyright Statement

   Copyright (C) The IETF Trust (2007).  This document is
   subject to the rights, licenses and restrictions contained in
   BCP 78, and except as set forth therein, the authors retain
   all their rights.

   This document and the information contained herein are
   provided on an "AS IS" basis and THE CONTRIBUTOR, THE
   ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY),
   THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET
   ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR
   IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE
   USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR
   ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A
   PARTICULAR PURPOSE.































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16 Intellectual Property Statement

   The IETF takes no position regarding the validity or scope of
   any Intellectual Property Rights or other rights that might
   be claimed to pertain to the implementation or use of the
   technology described in this document or the extent to which
   any license under such rights might or might not be
   available; nor does it represent that it has made any
   independent effort to identify any such rights.  Information
   on the procedures with respect to rights in RFC documents can
   be found in BCP 78 and BCP 79.

   Copies of IPR disclosures made to the IETF Secretariat and
   any assurances of licenses to be made available, or the
   result of an attempt made to obtain a general license or
   permission for the use of such proprietary rights by
   implementers or users of this specification can be obtained
   from the IETF on-line IPR repository at
   http://www.ietf.org/ipr.

   The IETF invites any interested party to bring to its
   attention any copyrights, patents or patent applications, or
   other proprietary rights that may cover technology that may
   be required to implement this standard.  Please address the
   information to the IETF at ietf-ipr@ietf.org.
























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