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RFC 5046

 
 
 

Internet Small Computer System Interface (iSCSI) Extensions for Remote Direct Memory Access (RDMA)

Part 2 of 4, p. 19 to 35
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3.  Upper Layer Interface Requirements

   This section discusses the upper layer interface requirements in the
   form of an abstract model of the required interactions between the
   iSCSI layer and the iSER layer.  The abstract model used here is
   derived from the architectural model described in [DA].  [DA] also
   provides a functional overview of the interactions between the iSCSI
   layer and the Datamover layer as intended by the Datamover
   Architecture.

   The interface requirements are specified by Operational Primitives.
   An Operational Primitive is an abstract functional interface
   procedure between the iSCSI layer and the iSER layer that requests
   one layer to perform a specific action on behalf of the other layer
   or notifies the other layer of some event.  Whenever an Operational
   Primitive in invoked, the Connection_Handle qualifier is used to
   identify a particular iSCSI connection.  For some Operational

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   Primitives, a Data_Descriptor is used to identify the iSCSI/SCSI data
   buffer associated with the requested or completed operation.

   The abstract model and the Operational Primitives defined in this
   section facilitate the description of the iSER protocol.  In the rest
   of the iSER specification, the compliance statements related to the
   use of these Operational Primitives are only for the purpose of the
   required interactions between the iSCSI layer and the iSER layer.
   Note that the compliance statements related to the Operational
   Primitives in the rest of this specification only mandate functional
   equivalence on implementations, but do not put any requirements on
   the implementation specifics of the interface between the iSCSI layer
   and the iSER layer.

   Each Operational Primitive is invoked with a set of qualifiers that
   specify the information context for performing the specific action
   being requested of the Operational Primitive.  While the qualifiers
   are required, the method of realizing the qualifiers (e.g., by
   passing synchronously with invocation, or by retrieving from task
   context, or by retrieving from shared memory, etc.) is implementation
   dependent.

3.1.  Operational Primitives Offered by iSER

   The iSER protocol layer MUST support the following Operational
   Primitives to be used by the iSCSI protocol layer.

3.1.1.  Send_Control

      Input qualifiers:  Connection_Handle, BHS and AHS (if any) of the
      iSCSI PDU, PDU-specific qualifiers

      Return results:  Not specified

   This is used by the iSCSI layers at the initiator and the target to
   request the outbound transfer of an iSCSI control-type PDU (see
   Section 7.2).  Qualifiers that only apply for a particular control-
   type PDU are known as PDU-specific qualifiers, e.g.,
   ImmediateDataSize for a SCSI write command.  For details on PDU-
   specific qualifiers, see Section 7.3.  The iSCSI layer can only
   invoke the Send_Control Operational Primitive when the connection is
   in iSER-assisted mode.

3.1.2.  Put_Data

      Input qualifiers:  Connection_Handle, content of a SCSI Data-in
      PDU header, Data_Descriptor, Notify_Enable

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      Return results:  Not specified

   This is used by the iSCSI layer at the target to request the outbound
   transfer of data for a SCSI Data-in PDU from the buffer identified by
   the Data_Descriptor qualifier.  The iSCSI layer can only invoke the
   Put_Data Operational Primitive when the connection is in iSER-
   assisted mode.

   The Notify_Enable qualifier is used to indicate to the iSER layer
   whether or not it should generate an eventual local completion
   notification to the iSCSI layer.  See Section 3.2.2 on
   Data_Completion_Notify for details.

3.1.3.  Get_Data

      Input qualifiers:  Connection_Handle, content of an R2T PDU,
      Data_Descriptor, Notify_Enable

      Return results:  Not specified

   This is used by the iSCSI layer at the target to request the inbound
   transfer of solicited data requested by an R2T PDU into the buffer
   identified by the Data_Descriptor qualifier.  The iSCSI layer can
   only invoke the Get_Data Operational Primitive when the connection is
   in iSER-assisted mode.

   The Notify_Enable qualifier is used to indicate to the iSER layer
   whether or not it should generate the eventual local completion
   notification to the iSCSI layer.  See Section 3.2.2 on
   Data_Completion_Notify for details.

3.1.4.  Allocate_Connection_Resources

      Input qualifiers:  Connection_Handle, Resource_Descriptor
      (optional)

      Return results:  Status

   This is used by the iSCSI layers at the initiator and the target to
   request the allocation of all connection resources necessary to
   support RCaP for an operational iSCSI/iSER connection.  The iSCSI
   layer may optionally specify the implementation-specific resource
   requirements for the iSCSI connection using the Resource_Descriptor
   qualifier.

   A return result of Status=success means that the invocation
   succeeded, and a return result of Status=failure means that the
   invocation failed.  If the invocation is for a Connection_Handle for

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   which an earlier invocation succeeded, the request will be ignored by
   the iSER layer and the result of Status=success will be returned.
   Only one Allocate_Connection_Resources Operational Primitive
   invocation can be outstanding for a given Connection_Handle at any
   time.

3.1.5.  Deallocate_Connection_Resources

      Input qualifiers:  Connection_Handle

      Return results:  Not specified

   This is used by the iSCSI layers at the initiator and the target to
   request the deallocation of all connection resources that were
   allocated earlier as a result of a successful invocation of the
   Allocate_Connection_Resources Operational Primitive.

3.1.6.  Enable_Datamover

      Input qualifiers:  Connection_Handle,
      Transport_Connection_Descriptor, Final Login_Response_PDU
      (optional)

      Return results:  Not specified

   This is used by the iSCSI layers at the initiator and the target to
   request that a specified iSCSI connection be transitioned to iSER-
   assisted mode.  The Transport_Connection_Descriptor qualifier is used
   to identify the specific connection associated with the
   Connection_Handle.  The iSCSI layer can only invoke the
   Enable_Datamover Operational Primitive when there is a corresponding
   prior resource allocation.

   The Final_Login_Response_PDU input qualifier is applicable only for a
   target, and contains the final Login Response PDU that concludes the
   iSCSI Login Phase.  If the underlying transport is TCP, the final
   Login Response PDU must be sent as a byte stream as expected by the
   iSCSI layer at the initiator.  When this qualifier is used, the iSER
   layer at the target MUST transmit this final Login Response PDU
   before transitioning to iSER-assisted mode.

3.1.7.  Connection_Terminate

      Input qualifiers:  Connection_Handle

      Return results:  Not specified

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   This is used by the iSCSI layers at the initiator and the target to
   request that a specified iSCSI/iSER connection be terminated and all
   associated connection and task resources be freed.  When this
   Operational Primitive invocation returns to the iSCSI layer, the
   iSCSI layer may assume full ownership of all iSCSI-level resources,
   e.g., I/O Buffers, associated with the connection.

3.1.8.  Notice_Key_Values

      Input qualifiers:  Connection_Handle, number of keys, list of
      Key-Value pairs

      Return results:  Not specified

   This is used by the iSCSI layers at the initiator and the target to
   request that the iSER layer take note of the specified Key-Value
   pairs that were negotiated by the iSCSI peers for the connection.

3.1.9.  Deallocate_Task_Resources

      Input qualifiers:  Connection_Handle, ITT

      Return results:  Not specified

   This is used by the iSCSI layers at the initiator and the target to
   request the deallocation of all RCaP-specific resources allocated by
   the iSER layer for the task identified by the ITT qualifier.  The
   iSER layer may require a certain number of RCaP-specific resources
   associated with the ITT for each new iSCSI task.  In the normal
   course of execution, these task-level resources in the iSER layer are
   assumed to be transparently allocated on each task initiation and
   deallocated on the conclusion of each task as appropriate.  In
   exception scenarios where the task does not conclude with a SCSI
   Response PDU, the iSER layer needs to be notified of the individual
   task terminations to aid its task-level resource management.  This
   Operational Primitive is used for this purpose, and is not needed
   when a SCSI Response PDU normally concludes a task.  Note that RCaP-
   specific task resources are deallocated by the iSER layer when a SCSI
   Response PDU normally concludes a task, even if the SCSI status was
   not success.

3.2.  Operational Primitives Used by iSER

   The iSER layer MUST use the following Operational Primitives offered
   by the iSCSI protocol layer when the connection is in iSER-assisted
   mode.

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3.2.1.  Control_Notify

      Input qualifiers:  Connection_Handle, an iSCSI control-type PDU

      Return results:  Not specified

   This is used by the iSER layers at the initiator and the target to
   notify the iSCSI layer of the availability of an inbound iSCSI
   control-type PDU.  A PDU is described as "available" to the iSCSI
   layer when the iSER layer notifies the iSCSI layer of the reception
   of that inbound PDU, along with an implementation-specific indication
   as to where the received PDU is.

3.2.2.  Data_Completion_Notify

      Input qualifiers:  Connection_Handle, ITT, SN

      Return results:  Not specified

   This is used by the iSER layer to notify the iSCSI layer of the
   completion of outbound data transfer that was requested by the iSCSI
   layer only if the invocation of the Put_Data Operational Primitive
   (see Section 3.1.2) was qualified with Notify_Enable set.  SN refers
   to the DataSN associated with the SCSI Data-in PDU.

   This is used by the iSER layer to notify the iSCSI layer of the
   completion of inbound data transfer that was requested by the iSCSI
   layer only if the invocation of the Get_Data Operational Primitive
   (see Section 3.1.3) was qualified with Notify_Enable set.  SN refers
   to the R2TSN associated with the R2T PDU.

3.2.3.  Data_ACK_Notify

      Input qualifier:  Connection_Handle, ITT, DataSN

      Return results:  Not specified

   This is used by the iSER layer at the target to notify the iSCSI
   layer of the arrival of the data acknowledgement (as defined in
   [RFC3720]) requested earlier by the iSCSI layer for the outbound data
   transfer via an invocation of the Put_Data Operational Primitive
   where the A-bit in the SCSI Data-in PDU is set to 1.  See Section
   7.3.5.  DataSN refers to the expected DataSN of the next SCSI Data-in
   PDU, which immediately follows the SCSI Data-in PDU with the A-bit
   set to which this notification corresponds, with semantics as defined
   in [RFC3720].

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3.2.4.  Connection_Terminate_Notify

      Input qualifiers:  Connection_Handle

      Return results:  Not specified

   This is used by the iSER layers at the initiator and the target to
   notify the iSCSI layer of the unsolicited termination or failure of
   an iSCSI/iSER connection.  The iSER layer MUST deallocate the
   connection and task resources associated with the terminated
   connection before the invocation of this Operational Primitive.  Note
   that the Connection_Terminate_Notify Operational Primitive is not
   invoked when the termination of the connection is earlier requested
   by the local iSCSI layer.

3.3.  iSCSI Protocol Usage Requirements

   To operate in an iSER-assisted mode, the iSCSI layers at both the
   initiator and the target MUST negotiate the RDMAExtensions key (see
   Section 6.3) to "Yes" on the leading connection.  If the
   RDMAExtensions key is not negotiated to "Yes", then iSER-assisted
   mode MUST NOT be used.  If the RDMAExtensions key is negotiated to
   "Yes" but the invocation of the Allocate_Connection_Resources
   Operational Primitive to the iSER layer fails, the iSCSI layer MUST
   fail the iSCSI Login process or terminate the connection as
   appropriate.  See Section 10.1.3.1 for details.

   If the RDMAExtensions key is negotiated to "Yes", the iSCSI layer
   MUST satisfy the following protocol usage requirements from the iSER
   protocol:

   1.  The iSCSI layer at the initiator MUST set ExpDataSN to 0 in Task
       Management Function Requests for Task Allegiance Reassignment for
       read/bidirectional commands, so as to cause the target to send
       all unacknowledged read data.

   2.  The iSCSI layer at the target MUST always return the SCSI status
       in a separate SCSI Response PDU for read commands, i.e., there
       MUST NOT be a "phase collapse" in concluding a SCSI read command.

   3.  The iSCSI layers at both the initiator and the target MUST
       support the keys as defined in Section 6 on Login/Text
       Operational Keys.  If used as specified, these keys MUST NOT be
       answered with NotUnderstood, and the semantics as defined MUST be
       followed for each iSER-assisted connection.

   4.  The iSCSI layer at the initiator MUST NOT issue SNACKs for PDUs.

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4.  Lower Layer Interface Requirements

4.1.  Interactions with the RCaP Layer

   The iSER protocol layer is layered on top of an RCaP layer (see
   Figure 1) and the following are the key features that are assumed to
   be supported by any RCaP layer:

   *  The RCaP layer supports all basic RDMA operations, including RDMA
      Write Operation, RDMA Read Operation, Send Operation, Send with
      Invalidate Operation, Send with Solicited Event Operation, Send
      with Solicited Event and Invalidate Operation, and Terminate
      Operation.

   *  The RCaP layer provides reliable, in-order message delivery and
      direct data placement.

   *  When the iSER layer initiates an RDMA Read Operation following an
      RDMA Write Operation on one RCaP Stream, the RDMA Read Response
      Message processing on the remote node will be started only after
      the preceding RDMA Write Message payload is placed in the memory
      of the remote node.

   *  The RCaP layer encapsulates a single iSER Message into a single
      RCaP Message on the Data Source side.  The RCaP layer decapsulates
      the iSER Message before delivering it to the iSER layer on the
      Data Sink side.

   *  When the iSER layer provides the STag to be remotely invalidated
      to the RCaP layer for a SendInvSE Message, the RCaP layer uses
      this STag as the STag to be invalidated in the SendInvSE Message.

   *  The RCaP layer uses the STag and Tagged Offset provided by the
      iSER layer for the RDMA Write and RDMA Read Request Messages.

   *  When the RCaP layer delivers the content of an RDMA Send Message
      Type to the iSER layer, the RCaP layer provides the length of the
      RDMA Send message.  This ensures that the iSER layer does not have
      to carry a length field in the iSER header.

   *  When the RCaP layer delivers the SendSE or SendInvSE Message to
      the iSER layer, it notifies the iSER layer with the mechanism
      provided on that interface.

   *  When the RCaP layer delivers a SendInvSE Message to the iSER
      layer, it passes the value of the STag that was invalidated.

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   *  The RCaP layer propagates all status and error indications to the
      iSER layer.

   *  For a transport layer that operates in byte stream mode such as
      TCP, the RCaP implementation supports the enabling of the RDMA
      mode after connection establishment and the exchange of Login
      parameters in byte stream mode.  For a transport layer that
      provides message delivery capability such as [IB], the RCaP
      implementation supports the use of the messaging capability by the
      iSCSI layer directly for the Login Phase after connection
      establishment before enabling iSER-assisted mode.

   *  Whenever the iSER layer terminates the RCaP Stream, the RCaP layer
      terminates the associated connection.

4.2.  Interactions with the Transport Layer

   The iSER layer does not directly setup the transport layer connection
   (e.g., TCP, or [IB]).  During connection setup, the iSCSI layer is
   responsible for setting up the connection.  If the login is
   successful, the iSCSI layer invokes the Enable_Datamover Operational
   Primitive to request the iSER layer to transition to the iSER-
   assisted mode for that iSCSI connection.  See Section 5.1 on
   iSCSI/iSER connection setup.  After transitioning to iSER-assisted
   mode, the RCaP layer and the underlying transport layer are
   responsible for maintaining the connection and reporting to the iSER
   layer any connection failures.

5.  Connection Setup and Termination

5.1.  iSCSI/iSER Connection Setup

   During connection setup, the iSCSI layer at the initiator is
   responsible for establishing a connection with the target.  After the
   connection is established, the iSCSI layers at the initiator and the
   target enter the Login Phase using the same rules as outlined in
   [RFC3720].  Transition to iSER-assisted mode occurs when the
   connection transitions into the iSCSI Full Feature Phase following a
   successful login negotiation between the initiator and the target in
   which iSER-assisted mode is negotiated and the connection resources
   necessary to support RCaP have been allocated at both the initiator
   and the target.  The same connection MUST be used for both the iSCSI
   Login Phase and the subsequent iSER-assisted Full Feature Phase.

   iSER-assisted mode MUST be enabled only if it is negotiated on the
   leading connection during the LoginOperationalNegotiation stage of
   the iSCSI Login Phase.  iSER-assisted mode is negotiated using the
   RDMAExtensions=<boolean-value> key.  Both the initiator and the

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   target MUST exchange the RDMAExtensions key with the value set to
   "Yes" to enable iSER-assisted mode.  If both the initiator and the
   target fail to negotiate the RDMAExtensions key set to "Yes", then
   the connection MUST continue with the login semantics as defined in
   [RFC3720].  If the RDMAExtensions key is not negotiated to Yes, then
   for some RCaP implementation (such as [IB]), the connection may need
   to be re-established in TCP capable mode.  (For InfiniBand this will
   require an [IPoIB] type connection.)

   iSER-assisted mode is defined for a Normal session only and the
   RDMAExtensions key MUST NOT be negotiated for a Discovery session.
   Discovery sessions are always conducted using the transport layer as
   described in [RFC3720].

   An iSER enabled node is not required to initiate the RDMAExtensions
   key exchange if its preference is for the Traditional iSCSI mode.
   The RDMAExtensions key, if offered, MUST be sent in the first
   available Login Response or Login Request PDU in the
   LoginOperationalNegotiation stage.  This is due to the fact that the
   value of some login parameters might depend on whether iSER-assisted
   mode is enabled.

   iSER-assisted mode is a session-wide attribute.  If both the
   initiator and the target negotiate RDMAExtensions="Yes" on the
   leading connection of a session, then all subsequent connections of
   the same session MUST enable iSER-assisted mode without having to
   exchange an RDMAExtensions key during the iSCSI Login Phase.

   Conversely, if both the initiator and the target fail to negotiate
   RDMAExtensions to "Yes" on the leading connection of a session, then
   the RDMAExtensions key MUST NOT be negotiated further on any
   additional subsequent connection of the session.

   When the RDMAExtensions key is negotiated to "Yes", the HeaderDigest
   and the DataDigest keys MUST be negotiated to "None" on all
   iSCSI/iSER connections participating in that iSCSI session.  This is
   because, for an iSCSI/iSER connection, RCaP is responsible for
   providing error detection that is at least as good as a 32-bit CRC
   for all iSER Messages.  Furthermore, all SCSI Read data are sent
   using RDMA Write Messages instead of the SCSI Data-in PDUs, and all
   solicited SCSI write data are sent using RDMA Read Response Messages
   instead of the SCSI Data-out PDUs.  HeaderDigest and DataDigest that
   apply to iSCSI PDUs, would not be appropriate for RDMA Read and RDMA
   Write operations used with iSER.

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5.1.1.  Initiator Behavior

   If the outcome of the iSCSI negotiation is to enable iSER-assisted
   mode, then on the initiator side, prior to sending the Login Request
   with the T (Transit) bit set to 1 and the NSG (Next Stage) field set
   to FullFeaturePhase, the iSCSI layer MUST request that the iSER layer
   allocate the connection resources necessary to support RCaP by
   invoking the Allocate_Connection_Resources Operational Primitive.
   The connection resources required are defined by implementation and
   are outside the scope of this specification.  The iSCSI layer may
   invoke the Notice_Key_Values Operational Primitive before invoking
   the Allocate_Connection_Resources Operational Primitive to request
   that the iSER layer take note of the negotiated values of the iSCSI
   keys for the connection.  The specific keys to be passed as input
   qualifiers are implementation dependent.  These may include, but are
   not limited to, MaxOutstandingR2T, ErrorRecoveryLevel, etc.

   To minimize the potential for a denial-of service attack, the iSCSI
   layer MUST NOT request that the iSER layer allocate the connection
   resources necessary to support RCaP until the iSCSI layer is
   sufficiently far along in the iSCSI Login Phase that it is reasonably
   certain that the peer side is not an attacker.  In particular, if the
   Login Phase includes a SecurityNegotiation stage, the iSCSI layer
   MUST defer the connection resource allocation (i.e., invoking the
   Allocate_Connection_Resources Operational Primitive) to the
   LoginOperationalNegotiation stage [RFC3720] so that the resource
   allocation occurs after the authentication phase is completed.

   Among the connection resources allocated at the initiator is the
   Inbound RDMA Read Queue Depth (IRD).  As described in Section 9.5.1,
   R2Ts are transformed by the target into RDMA Read operations.  IRD
   limits the maximum number of simultaneously incoming outstanding RDMA
   Read Requests per an RCaP Stream from the target to the initiator.
   The required value of IRD is outside the scope of the iSER
   specification.  The iSER layer at the initiator MUST set IRD to 1 or
   higher if R2Ts are to be used in the connection.  However, the iSER
   layer at the initiator MAY set IRD to 0 based on implementation
   configuration, which indicates that no R2Ts will be used on that
   connection.  Initially, the iSER-IRD value at the initiator SHOULD be
   set to the IRD value at the initiator and MUST NOT be more than the
   IRD value.

   On the other hand, the Outbound RDMA Read Queue Depth (ORD) MAY be
   set to 0, since the iSER layer at the initiator does not issue RDMA
   Read Requests to the target.

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   Failure to allocate the requested connection resources locally
   results in a login failure and its handling is described in Section
   10.1.3.1.

   If the iSER layer at the initiator is successful in allocating the
   connection resources necessary to support RCaP, the following events
   MUST occur in the specified sequence:

   1.  The iSER layer MUST return a success status to the iSCSI layer in
       response to the Allocate_Connection_Resources Operational
       Primitive.

   2.  After the target returns the Login Response with the T bit set to
       1 and the NSG field set to FullFeaturePhase, and a status class
       of 0 (Success), the iSCSI layer MUST request that the iSER layer
       transition to iSER-assisted mode by invoking the Enable_Datamover
       Operational Primitive with the following qualifiers.  (See
       Section 10.1.4.6 for the case when the status class is not
       Success.):

       a.  Connection_Handle that identifies the iSCSI connection.

       b.  Transport_Connection_Descriptor that identifies the specific
           transport connection associated with the Connection_Handle.

   3.  If necessary, the iSER layer should enable RCaP and transition
       the connection to iSER-assisted mode.  When the RCaP is iWARP,
       then this step MUST be done.  Not all RCaPs may need it depending
       on the RCaP Stream start-up state.

   4.  The iSER layer MUST send the iSER Hello Message as the first iSER
       Message.  See Section 5.1.3 on iSER Hello Exchange.

5.1.2.  Target Behavior

   If the outcome of the iSCSI negotiation is to enable iSER-assisted
   mode, then on the target side, prior to sending the Login Response
   with the T (Transit) bit set to 1 and the NSG (Next Stage) field set
   to FullFeaturePhase, the iSCSI layer MUST request that the iSER layer
   allocate the resources necessary to support RCaP by invoking the
   Allocate_Connection_Resources Operational Primitive.  The connection
   resources required are defined by implementation and are outside the
   scope of this specification.  Optionally, the iSCSI layer may invoke
   the Notice_Key_Values Operational Primitive before invoking the
   Allocate_Connection_Resources Operational Primitive to request that
   the iSER layer take note of the negotiated values of the iSCSI keys
   for the connection.  The specific keys to be passed as input

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   qualifiers are implementation dependent.  These may include, but are
   not limited to, MaxOutstandingR2T, ErrorRecoveryLevel, etc.

   To minimize the potential for a denial-of-service attack, the iSCSI
   layer MUST NOT request that the iSER layer allocate the connection
   resources necessary to support RCaP until the iSCSI layer is
   sufficiently far along in the iSCSI Login Phase that it is reasonably
   certain that the peer side is not an attacker.  In particular, if the
   Login Phase includes a SecurityNegotiation stage, the iSCSI layer
   MUST defer the connection resource allocation (i.e., invoking the
   Allocate_Connection_Resources Operational Primitive) to the
   LoginOperationalNegotiation stage [RFC3720] so that the resource
   allocation occurs after the authentication phase is completed.

   Among the connection resources allocated at the target is the
   Outbound RDMA Read Queue Depth (ORD).  As described in Section 9.5.1,
   R2Ts are transformed by the target into RDMA Read operations.  The
   ORD limits the maximum number of simultaneously outstanding RDMA Read
   Requests per RCaP Stream from the target to the initiator.
   Initially, the iSER-ORD value at the target SHOULD be set to the ORD
   value at the target.

   On the other hand, the IRD at the target MAY be set to 0 since the
   iSER layer at the target does not expect RDMA Read Requests to be
   issued by the initiator.

   Failure to allocate the requested connection resources locally
   results in a login failure and its handling is described in Section
   10.1.3.1.

   If the iSER layer at the target is successful in allocating the
   connection resources necessary to support RCaP, the following events
   MUST occur in the specified sequence:

   1.  The iSER layer MUST return a success status to the iSCSI layer in
       response to the Allocate_Connection_Resources Operational
       Primitive.

   2.  The iSCSI layer MUST request that the iSER layer transition to
       iSER-assisted mode by invoking the Enable_Datamover Operational
       Primitive with the following qualifiers:

       a.  Connection_Handle that identifies the iSCSI connection.

       b.  Transport_Connection_Descriptor that identifies the specific
           transport connection associated with the Connection_Handle.

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       c.  The final transport layer (e.g., TCP) message containing the
           Login Response with the T bit set to 1 and the NSG field set
           to FullFeaturePhase.

   3.  The iSER layer MUST send the final Login Response PDU in the
       native transport mode to conclude the iSCSI Login Phase.  If the
       underlying transport is TCP, then the iSER layer MUST send the
       final Login Response PDU in byte stream mode.

   4.  After sending the final Login Response PDU, the iSER layer should
       enable RCaP if necessary and transition the connection to iSER-
       assisted mode.  When the RCaP is iWARP, then this step MUST be
       done.  Not all RCaPs may need it depending on the RCaP Stream
       start-up state.

   5.  After receiving the iSER Hello Message from the initiator, the
       iSER layer MUST respond with the iSER HelloReply Message to be
       sent as the first iSER Message.  See Section 5.1.3 on iSER Hello
       Exchange for more details.

   Note: In the above sequence, the operations as described in bullets 3
   and 4 MUST be performed atomically for iWARP connections.  Failure to
   do this may result in race conditions.

5.1.3.  iSER Hello Exchange

   After the connection transitions into iSER-assisted mode, the first
   iSER Message sent by the iSER layer at the initiator to the target
   MUST be the iSER Hello Message.  The iSER Hello Message is used by
   the iSER layer at the initiator to declare iSER parameters to the
   target.  See Section 9.3 on iSER Header Format for the iSER Hello
   Message.

   In response to the iSER Hello Message, the iSER layer at the target
   MUST return the iSER HelloReply Message as the first iSER Message
   sent by the target.  The iSER HelloReply Message is used by the iSER
   layer at the target to declare iSER parameters to the initiator.  See
   Section 9.4 on iSER Header Format for the iSER HelloReply Message.

   In the iSER Hello Message, the iSER layer at the initiator declares
   the iSER-IRD value to the target.

   Upon receiving the iSER Hello Message, the iSER layer at the target
   MUST set the iSER-ORD value to the minimum of the iSER-ORD value at
   the target and the iSER-IRD value declared by the initiator.  The
   iSER layer at the target MAY adjust (lower) its ORD value to match
   the iSER-ORD value if the iSER-ORD value is smaller than the ORD
   value at the target in order to free up the unused resources.

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   In the iSER HelloReply Message, the iSER layer at the target declares
   the iSER-ORD value to the initiator.

   Upon receiving the iSER HelloReply Message, the iSER layer at the
   initiator MAY adjust (lower) its IRD value to match the iSER-ORD
   value in order to free up the unused resources, if the iSER-ORD value
   declared by the target is smaller than the iSER-IRD value declared by
   the initiator.

   It is an iSER level negotiation failure if the iSER parameters
   declared in the iSER Hello Message by the initiator are unacceptable
   to the target.  This includes the following:

   *  The initiator-declared iSER-IRD value is greater than 0 and the
      target-declared iSER-ORD value is 0.

   *  The initiator-supported and the target-supported iSER protocol
      versions do not overlap.

   See Section 10.1.3.2 for the handling of the error situation.

5.2.  iSCSI/iSER Connection Termination

5.2.1.  Normal Connection Termination at the Initiator

   The iSCSI layer at the initiator terminates an iSCSI/iSER connection
   normally by invoking the Send_Control Operational Primitive qualified
   with the Logout Request PDU.  The iSER layer at the initiator MUST
   use a SendSE Message to send the Logout Request PDU to the target.
   After the iSER layer at the initiator receives the SendSE Message
   containing the Logout Response PDU from the target, it MUST notify
   the iSCSI layer by invoking the Control_Notify Operational Primitive
   qualified with the Logout Response PDU.

   After the iSCSI logout process is complete, the iSCSI layer at the
   target is responsible for closing the iSCSI/iSER connection as
   described in Section 5.2.2.  After the RCaP layer at the initiator
   reports that the connection has been closed, the iSER layer at the
   initiator MUST deallocate all connection and task resources (if any)
   associated with the connection, and invalidate the Local Mapping(s)
   (if any) that associate the ITT(s) used on that connection to the
   local STag(s) before notifying the iSCSI layer by invoking the
   Connection_Terminate_Notify Operational Primitive.

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5.2.2.  Normal Connection Termination at the Target

   Upon receiving the SendSE Message containing the Logout Request PDU,
   the iSER layer at the target MUST notify the iSCSI layer at the
   target by invoking the Control_Notify Operational Primitive qualified
   with the Logout Request PDU.  The iSCSI layer completes the logout
   process by invoking the Send_Control Operational Primitive qualified
   with the Logout Response PDU.  The iSER layer at the target MUST use
   a SendSE Message to send the Logout Response PDU to the initiator.
   After the iSCSI logout process is complete, the iSCSI layer at the
   target MUST request that the iSER layer at the target terminate the
   RCaP Stream by invoking the Connection_Terminate Operational
   Primitive.

   As part of the termination process, the RCaP layer MUST close the
   connection.  When the RCaP layer notifies the iSER layer after the
   RCaP Stream and the associated connection are terminated, the iSER
   layer MUST deallocate all connection and task resources (if any)
   associated with the connection, and invalidate the Local and Remote
   Mapping(s) (if any) that associate the ITT(s) used on that connection
   to the local STag(s) and the Advertised STag(s) respectively.

5.2.3.  Termination without Logout Request/Response PDUs

5.2.3.1.  Connection Termination Initiated by the iSCSI Layer

   The Connection_Terminate Operational Primitive MAY be invoked by the
   iSCSI layer to request that the iSER layer terminate the RCaP Stream
   without having previously exchanged the Logout Request and Logout
   Response PDUs between the two iSCSI/iSER nodes.  As part of the
   termination process, the RCaP layer will close the connection.  When
   the RCaP layer notifies the iSER layer after the RCaP Stream and the
   associated connection are terminated, the iSER layer MUST perform the
   following actions.

   If the Connection_Terminate Operational Primitive is invoked by the
   iSCSI layer at the target, then the iSER layer at the target MUST
   deallocate all connection and task resources (if any) associated with
   the connection, and invalidate the Local and Remote Mappings (if any)
   that associate the ITT(s) used on the connection to the local STag(s)
   and the Advertised STag(s), respectively.

   If the Connection_Terminate Operational Primitive is invoked by the
   iSCSI layer at the initiator, then the iSER layer at the initiator
   MUST deallocate all connection and task resources (if any) associated
   with the connection, and invalidate the Local Mapping(s) (if any)
   that associate the ITT(s) used on the connection to the local
   STag(s).

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5.2.3.2.  Connection Termination Notification to the iSCSI Layer

   If the iSCSI/iSER connection is terminated without the invocation of
   Connection_Terminate from the iSCSI layer, the iSER layer MUST notify
   the iSCSI layer that the iSCSI/iSER connection has been terminated by
   invoking the Connection_Terminate_Notify Operational Primitive.

   Prior to invoking Connection_Terminate_Notify, the iSER layer at the
   target MUST deallocate all connection and task resources (if any)
   associated with the connection, and invalidate the Local and Remote
   Mappings (if any) that associate the ITT(s) used on the connection to
   the local STag(s) and the Advertised STag(s), respectively.

   Prior to invoking Connection_Terminate_Notify, the iSER layer at the
   initiator MUST deallocate all connection and task resources (if any)
   associated with the connection, and invalidate the Local Mappings (if
   any) that associate the ITT(s) used on the connection to the local
   STag(s).

   If the remote iSCSI/iSER node initiated the closing of the connection
   (e.g., by sending a TCP FIN or TCP RST), the iSER layer MUST notify
   the iSCSI layer after the RCaP layer reports that the connection is
   closed by invoking the Connection_Terminate_Notify Operational
   Primitive.

   Another example of a connection termination without a preceding
   logout is when the iSCSI layer at the initiator does an implicit
   logout (connection reinstatement).



(page 35 continued on part 3)

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