A Remote Direct Memory Access Protocol Specification
draft-ietf-rddp-rdmap-07
The information below is for an old version of the document that is already published as an RFC.
| Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 5040.
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|
|---|---|---|---|
| Authors | Renato J. Recio , Paul R. Culley , Dave Garcia , Bernard Metzler , Jeff Hilland | ||
| Last updated | 2015-10-14 (Latest revision 2006-09-10) | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | Proposed Standard | ||
| Formats | |||
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| Additional resources | Mailing list discussion | ||
| Stream | WG state | (None) | |
| Document shepherd | (None) | ||
| IESG | IESG state | Became RFC 5040 (Proposed Standard) | |
| Action Holders |
(None)
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||
| Consensus boilerplate | Unknown | ||
| Telechat date | (None) | ||
| Responsible AD | Lars Eggert | ||
| Send notices to | hemal.shah@intel.com, jpink@microsoft.com |
draft-ietf-rddp-rdmap-07
Remote Direct Data Placement Work Group R. Recio
INTERNET DRAFT IBM Corporation
draft-ietf-rddp-rdmap-07.txt P. Culley
Hewlett-Packard Company
D. Garcia
Hewlett-Packard Company
J. Hilland
Hewlett-Packard Company
B. Metzler
IBM Corporation
Expires: February, 2007 September 8, 2006
A Remote Direct Memory Access Protocol Specification
Status of this Memo
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Abstract
This document defines a Remote Direct Memory Access Protocol
(RDMAP) that operates over the Direct Data Placement Protocol (DDP
protocol). RDMAP provides read and write services directly to
applications and enables data to be transferred directly into
Upper Layer Protocol (ULP) buffers without intermediate data
copies. It also enables a kernel bypass implementation.
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Table of Contents
1 Introduction................................................6
1.1 Architectural Goals.........................................6
1.2 Protocol Overview...........................................7
1.3 RDMAP Layering.............................................10
1.4 Specification Changes from the Last Version................11
2 Glossary...................................................14
2.1 General....................................................14
2.2 LLP........................................................16
2.3 Direct Data Placement (DDP)................................17
2.4 Remote Direct Memory Access (RDMA).........................19
3 ULP and Transport Attributes...............................22
3.1 Transport Requirements & Assumptions.......................22
3.2 RDMAP Interactions with the ULP............................23
4 Header Format..............................................27
4.1 RDMAP Control and Invalidate STag Field....................27
4.2 RDMA Message Definitions...................................30
4.3 RDMA Write Header..........................................31
4.4 RDMA Read Request Header...................................32
4.5 RDMA Read Response Header..................................34
4.6 Send Header and Send with Solicited Event Header...........34
4.7 Send with Invalidate Header and Send with SE and Invalidate
Header...........................................................34
4.8 Terminate Header...........................................34
5 Data Transfer..............................................41
5.1 RDMA Write Message.........................................41
5.2 RDMA Read Operation........................................42
5.2.1 RDMA Read Request Message.................................42
5.2.2 RDMA Read Response Message................................43
5.3 Send Message Type..........................................44
5.4 Terminate Message..........................................46
5.5 Ordering and Completions...................................47
6 RDMAP Stream Management....................................51
6.1 Stream Initialization......................................51
6.2 Stream Teardown............................................52
6.2.1 RDMAP Abortive Termination................................52
7 RDMAP Error Management.....................................54
7.1 RDMAP Error Surfacing......................................54
7.2 Errors Detected at the Remote Peer on Incoming RDMA Messages55
8 Security Considerations....................................57
8.1 Summary of RDMAP specific Security Requirements............57
8.1.1 RDMAP (RNIC) Requirements.................................57
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8.1.2 Privileged Resource Manager Requirements..................59
8.2 Security Services for RDMAP................................60
8.2.1 Available Security Services...............................60
8.2.2 Requirements for IPsec Services for RDMAP.................61
9 IANA.......................................................64
10 References.................................................65
10.1 Normative References......................................65
10.2 Informative References....................................66
11 Appendix...................................................67
11.1 DDP Segment Formats for RDMA Messages.....................67
11.1.1 DDP Segment for RDMA Write..............................67
11.1.2 DDP Segment for RDMA Read Request.......................67
11.1.3 DDP Segment for RDMA Read Response......................69
11.1.4 DDP Segment for Send and Send with Solicited Event......69
11.1.5 DDP Segment for Send with Invalidate and Send with SE and
Invalidate.......................................................70
11.1.6 DDP Segment for Terminate...............................71
11.2 Ordering and Completion Table.............................71
12 Author's Address...........................................75
13 Contributors...............................................76
14 Intellectual Property Statement............................80
15 Full Copyright Statement...................................81
Table of Figures
Figure 1 RDMAP Layering..........................................10
Figure 2 Example of MPA, DDP, and RDMAP Header Alignment over TCP11
Figure 3 DDP Control, RDMAP Control, and Invalidate STag Fields..28
Figure 4 RDMA Usage of DDP Fields................................29
Figure 5 RDMA Message Definitions................................31
Figure 6 RDMA Read Request Header Format.........................32
Figure 7 Terminate Header Format.................................35
Figure 8 Terminate Control Field.................................35
Figure 9 Terminate Control Field Values..........................38
Figure 10 Error Type to RDMA Message Mapping.....................40
Figure 11 RDMA Write, DDP Segment format.........................67
Figure 12 RDMA Read Request, DDP Segment format..................68
Figure 13 RDMA Read Response, DDP Segment format.................69
Figure 14 Send and Send with Solicited Event, DDP Segment format.70
Figure 15 Send with Invalidate and Send with SE and Invalidate,
DDP Segment......................................................70
Figure 16 Terminate, DDP Segment format..........................71
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Figure 17 Operation Ordering.....................................74
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1 Introduction
Today, communications over TCP/IP typically require copy
operations, which add latency and consume significant CPU and
memory resources. The Remote Direct Memory Access Protocol
(RDMAP) enables removal of data copy operations and enables
reduction in latencies by allowing a local application to read or
write data on a remote computer's memory with minimal demands on
memory bus bandwidth and CPU processing overhead, while preserving
memory protection semantics.
RDMAP is layered on top of Direct Data Placement (DDP) and uses
the two Buffer Models available from DDP. DDP-related terminology
is discussed in Section 2.3. As RDMAP builds on DDP the reader is
advised to become familiar with [DDP].
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 RFC 2119."
1.1 Architectural Goals
RDMAP has been designed with the following high-level
architectural goals:
* Provide a data transfer operation that allows a Local Peer to
transfer up to 2^32 - 1 octets directly into a previously
advertised buffer (i.e., Tagged buffer) located at a Remote
Peer without requiring a copy operation. This is referred to as
the RDMA Write data transfer operation.
* Provide a data transfer operation that allows a Local Peer to
retrieve up to 2^32 - 1 octets directly from a previously
advertised buffer (i.e., Tagged buffer) located at a Remote
Peer without requiring a copy operation. This is referred to as
the RDMA Read data transfer operation.
* Provide a data transfer operation that allows a Local Peer to
send up to 2^32 - 1 octets directly into a buffer located at a
Remote Peer that has not been explicitly advertised. This is
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referred to as the Send (Send with Invalidate, Send with
Solicited Event, and Send with Solicited Event and Invalidate)
data transfer operation.
* Enable the local ULP to use the Send Operation Type (includes
Send, Send with Invalidate, Send with Solicited Event, and Send
with Solicited Event and Invalidate) to signal to the remote
ULP the Completion of all previous Messages initiated by the
local ULP.
* Provide for all Operations on a single RDMAP Stream to be
reliably transmitted in the order that they were submitted.
* Provide RDMAP capabilities independently for each Stream when
the LLP supports multiple data Streams within an LLP
connection.
1.2 Protocol Overview
RDMAP provides seven data transfer operations. Except for the RDMA
Read operation, each operation generates exactly one RDMA Message.
Following is a brief overview of the RDMA Operations and RDMA
Messages:
1. Send - A Send operation uses a Send Message to transfer data
from the Data Source into a buffer that has not been
explicitly Advertised by the Data Sink. The Send Message uses
the DDP Untagged Buffer Model to transfer the ULP Message into
the Data Sink's Untagged Buffer.
2. Send with Invalidate - A Send with Invalidate operation uses a
Send with Invalidate Message to transfer data from the Data
Source into a buffer that has not been explicitly Advertised
by the Data Sink. The Send with Invalidate Message includes
all functionality of the Send Message, with one addition: an
STag field is included in the Send with Invalidate Message and
after the message has been Placed and Delivered at the Data
Sink the remote peer's buffer identified by the STag can no
longer be accessed remotely until the remote peer's ULP re-
enables access and Advertises the buffer.
3. Send with Solicited Event (Send with SE) - A Send with
Solicited Event operation uses a Send with Solicited Event
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Message to transfer data from the Data Source into an Untagged
Buffer at the Data Sink. The Send with Solicited Event Message
is similar to the Send Message, with one addition: when the
Send with Solicited Event Message has been Placed and
Delivered, an Event may be generated at the recipient, if the
recipient is configured to generate such an Event.
4. Send with Solicited Event and Invalidate (Send with SE and
Invalidate) - A Send with Solicited Event and Invalidate
operation uses a Send with Solicited Event and Invalidate
Message to transfer data from the Data Source into a buffer
that has not been explicitly Advertised by the Data Sink. The
Send with Solicited Event and Invalidate Message is similar to
the Send with Invalidate Message, with one addition: when the
Send with Solicited Event and Invalidate Message has been
Placed and Delivered, an Event may be generated at the
recipient, if the recipient is configured to generate such an
Event.
5. Remote Direct Memory Access Write - An RDMA Write operation
uses an RDMA Write Message to transfer data from the Data
Source to a previously advertised buffer at the Data Sink.
The ULP at the Remote Peer, which in this case is the Data
Sink, enables the Data Sink Tagged Buffer for access and
Advertises the buffer's size (length), location (Tagged
Offset), and Steering Tag (STag) to the Data Source through a
ULP specific mechanism. The ULP at the Local Peer, which in
this case is the Data Source, initiates the RDMA Write
operation. The RDMA Write Message uses the DDP Tagged Buffer
Model to transfer the ULP Message into the Data Sink's Tagged
Buffer. Note: the STag associated with the Tagged Buffer
remains valid until the ULP at the Remote Peer invalidates it
or the ULP at the Local Peer invalidates it through a Send
with Invalidate or Send with Solicited Event and Invalidate.
6. Remote Direct Memory Access Read - The RDMA Read operation
transfers data to a Tagged Buffer at the Local Peer, which in
this case is the Data Sink, from a Tagged Buffer at the Remote
Peer, which in this case is the Data Source. The ULP at the
Data Source enables the Data Source Tagged Buffer for access
and Advertises the buffer's size (length), location (Tagged
Offset), and Steering Tag (STag) to the Data Sink through a
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ULP specific mechanism. The ULP at the Data Sink enables the
Data Sink Tagged Buffer for access and initiates the RDMA Read
operation. The RDMA Read operation consists of a single RDMA
Read Request Message and a single RDMA Read Response Message,
and the latter may be segmented into multiple DDP Segments.
The RDMA Read Request Message uses the DDP Untagged Buffer
Model to Deliver the STag, starting Tagged Offset and length
for both the Data Source and Data Sink Tagged Buffers to the
remote peer's RDMA Read Request Queue.
The RDMA Read Response Message uses the DDP Tagged Buffer
Model to Deliver the Data Source's Tagged Buffer to the Data
Sink, without any involvement from the ULP at the Data Source.
Note: the Data Source STag associated with the Tagged Buffer
remains valid until the ULP at the Data Source invalidates it
or the ULP at the Data Sink invalidates it through a Send with
Invalidate or Send with Solicited Event and Invalidate. The
Data Sink STag associated with the Tagged Buffer remains valid
until the ULP at the Data Sink invalidates it.
7. Terminate - A Terminate operation uses a Terminate Message to
transfer to the Remote Peer information associated with an
error that occurred at the Local Peer. The Terminate Message
uses the DDP Untagged Buffer Model to transfer the Message
into the Data Sink's Untagged Buffer.
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1.3 RDMAP Layering
RDMAP is dependent on DDP, subject to the requirements defined in
section 3.1 Transport Requirements & Assumptions. Figure 1 RDMAP
Layering depicts the relationship between Upper Layer Protocols
(ULPs), RDMAP, DDP protocol, the framing layer, and the transport.
For LLP protocol definitions of each LLP, see [MPA], [TCP], and
[SCTP].
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Upper Layer Protocol (ULP) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| RDMAP |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| DDP protocol |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | |
| MPA | |
| | |
+-+-+-+-+-+-+-+-+-+ SCTP |
| | |
| TCP | |
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1 RDMAP Layering
If RDMAP is layered over DDP/MPA/TCP, then the respective headers
and ULP Payload are arranged as follows (Note: For clarity, MPA
header and CRC fields are included but MPA markers are not shown):
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// TCP Header //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MPA Header | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
// DDP Header //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// RDMA Header //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// ULP Payload //
// (shown with no pad bytes) //
// //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MPA CRC |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2 Example of MPA, DDP, and RDMAP Header Alignment over TCP
1.4 Specification Changes from the Last Version
This section is to be removed before RFC publication.
The following major changes (vs typos) were made to the -06 and -
07 version:
* Incorporated comments from Transport Area Directors and the
Remote Direct Data Placement Working Group chair.
The following major changes (vs typos) were made to the -05
version:
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* To pass the IETF checklist tool, modified heading of Security
Section 8 to "Security" and added "Security Considerations"
below it.
* Added IANA Section 9 and to pass the IETF checklist tool added
"IANA Considerations" line below Section 9 header.
* Added Intellectual Property Statement Section 14 and IPR
Disclosure Acknowledgement Section 15.
* Added Disclaimer Section 16.
* Section 6.8 - Acknowledged that the Reserved field size for the
Terminate Message is 13 bits. The fix was made to the -04
version, but was not listed in this section.
* Rewrite of the "Security" section to refer to Security document
rather than summarize.
* Update to the "Contributors" section.
* Changed boilerplate reference form 3667 to 3979.
* Removed references to company names in the disclaimer section.
* Added "Key Words" Disclaimer to the Introduction.
The following major changes (vs typos) were made to the -04
version:
* Section 10 - Expanded IPsec requirements sentence in section
10.3.2 to say what is required in addition to cross-referencing
RFC 3723.
* Section 6.8 - Fixed text after Figure 9 to reflect the correct
size (13 bits) of the Reserved field in the Terminate Message.
The following major changes (vs typos) were made to the -03
version:
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* Section 6.1 - Added normative text describing downward
compatibility with version 0.
* Section 6.8 - Changed the description of the reserved field
size to match the size in the figure, which is 13 bits.
* Section 10 - Aligned security section closely to [RDMASEC] and
added normative text for security requirements.
The following major changes (vs typos) were made to the -02
version:
* Section 6.8 - Explicitly defined the bit numbers for the three
header control bits.
* Section 8.1 - Stated the typical Stream initialization to be:
RDMA mode is entered some time after the LLP Stream is
initialized.
* Section 10 - Update reference to security document.
* Section 10 - Fixed Send with Solicited Event and Invalidate
reference.
* Section 12.1 - MPA and DDP references were changed to reflect
the released specifications and accurate titles.
* Section 12.1 - Reference for RDMA Protocol Verbs was changed to
reflect the released specification and accurate title.
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2 Glossary
2.1 General
Advertisement (Advertised, Advertise, Advertisements, Advertises)
- the act of informing a Remote Peer that a local RDMA Buffer
is available to it. A Node makes available an RDMA Buffer for
incoming RDMA Read or RDMA Write access by informing its
RDMA/DDP peer of the Tagged Buffer identifiers (STag, base
address, and buffer length). This Advertisement of Tagged
Buffer information is not defined by RDMA/DDP and is left to
the ULP. A typical method would be for the Local Peer to embed
the Tagged Buffer's Steering Tag, base address, and length in
a Send Message destined for the Remote Peer.
Completion - Refer to "RDMA Completion" in Section 2.4.
Completed - See "RDMA Completion" in Section 2.4.
Complete - See "RDMA Completion" in Section 2.4.
Completes - See "RDMA Completion" in Section 2.4.
Data Sink - The peer receiving a data payload. Note that the Data
Sink can be required to both send and receive RDMA/DDP
Messages to transfer a data payload.
Data Source - The peer sending a data payload. Note that the Data
Source can be required to both send and receive RDMA/DDP
Messages to transfer a data payload.
Data Delivery (Delivery, Delivered, Delivers) - Delivery is
defined as the process of informing the ULP or consumer that a
particular Message is available for use. This is specifically
different from "Placement", which may generally occur in any
order, while the order of "Delivery" is strictly defined. See
"Data Placement" in Section 2.3.
Delivery - See Data Delivery in Section 2.1.
Delivered - See Data Delivery in Section 2.1.
Delivers - See Data Delivery in Section 2.1.
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Fabric - The collection of links, switches, and routers that
connect a set of Nodes with RDMA/DDP protocol implementations.
Fence (Fenced, Fences) - To block the current RDMA Operation from
executing until prior RDMA Operations have Completed.
iWARP - A suite of wire protocols comprised of RDMAP, DDP, and
MPA. The iWARP protocol suite may be layered above TCP, SCTP,
or other transport protocols.
Local Peer - The RDMA/DDP protocol implementation on the local end
of the connection. Used to refer to the local entity when
describing a protocol exchange or other interaction between
two Nodes.
Node - A computing device attached to one or more links of a
Fabric (network). A Node in this context does not refer to a
specific application or protocol instantiation running on the
computer. A Node may consist of one or more RNICs installed in
a host computer.
Placement - See "Data Placement" in Section 2.3
Placed - See "Data Placement" in Section 2.3
Places - See "Data Placement" in Section 2.3
Remote Peer - The RDMA/DDP protocol implementation on the opposite
end of the connection. Used to refer to the remote entity when
describing protocol exchanges or other interactions between
two Nodes.
RNIC - RDMA Network Interface Controller. In this context, this
would be a network I/O adapter or embedded controller with
iWARP and Verbs functionality.
RNIC Interface (RI) - The presentation of the RNIC to the Verbs
Consumer as implemented through the combination of the RNIC
and the RNIC driver.
Termination - See "RDMAP Abortive Termination" in Section 2.4.
Terminated - See "RDMAP Abortive Termination" in Section 2.4.
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Terminate - See "RDMAP Abortive Termination" in Section 2.4
Terminates - See "RDMAP Abortive Termination" in Section 2.4
ULP - Upper Layer Protocol. The protocol layer above the protocol
layer currently being referenced. The ULP for RDMA/DDP is
expected to be an OS, Application, adaptation layer, or
proprietary device. The RDMA/DDP documents do not specify a
ULP - they provide a set of semantics that allow a ULP to be
designed to utilize RDMA/DDP.
ULP Payload - The ULP data that is contained within a single
protocol segment or packet (e.g., a DDP Segment).
Verbs - An abstract description of the functionality of a RNIC
Interface. The OS may expose some or all of this functionality
via one or more APIs to applications. The OS will also use
some of the functionality to manage the RNIC Interface.
2.2 LLP
LLP - Lower Layer Protocol. The protocol layer beneath the
protocol layer currently being referenced. For example, for
DDP the LLP is SCTP, MPA, or other transport protocols. For
RDMA, the LLP is DDP.
LLP Connection - Corresponds to an LLP transport-level connection
between the peer LLP layers on two nodes.
LLP Stream - Corresponds to a single LLP transport-level Stream
between the peer LLP layers on two Nodes. One or more LLP
Streams may map to a single transport-level LLP connection.
For transport protocols that support multiple Streams per
connection (e.g., SCTP), a LLP Stream corresponds to one
transport-level Stream.
MULPDU - Maximum ULPDU. The current maximum size of the record
that is acceptable for DDP to pass to the LLP for
transmission.
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ULPDU - Upper Layer Protocol Data Unit. The data record defined
by the layer above MPA.
2.3 Direct Data Placement (DDP)
Data Placement (Placement, Placed, Places) - For DDP, this term is
specifically used to indicate the process of writing to a data
buffer by a DDP implementation. DDP Segments carry Placement
information, which may be used by the receiving DDP
implementation to perform Data Placement of the DDP Segment
ULP Payload. See "Data Delivery".
DDP Abortive Teardown - The act of closing a DDP Stream without
attempting to Complete in-progress and pending DDP Messages.
DDP Graceful Teardown - The act of closing a DDP Stream such that
all in-progress and pending DDP Messages are allowed to
Complete successfully.
DDP Control Field - a fixed 16-bit field in the DDP Header. The
DDP Control Field contains an 8-bit field whose contents are
reserved for use by the ULP.
DDP Header - The header present in all DDP segments. The DDP
Header contains control and Placement fields that are used to
define the final Placement location for the ULP payload
carried in a DDP Segment.
DDP Message - A ULP defined unit of data interchange, which is
subdivided into one or more DDP segments. This segmentation
may occur for a variety of reasons, including segmentation to
respect the maximum segment size of the underlying transport
protocol.
DDP Segment - The smallest unit of data transfer for the DDP
protocol. It includes a DDP Header and ULP Payload (if
present). A DDP Segment should be sized to fit within the
underlying transport protocol MULPDU.
DDP Stream - a sequence of DDP Messages whose ordering is defined
by the LLP. For SCTP, a DDP Stream maps directly to an SCTP
Stream. For MPA, a DDP Stream maps directly to a TCP
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connection and a single DDP Stream is supported. Note that
DDP has no ordering guarantees between DDP Streams.
Direct Data Placement - A mechanism whereby ULP data contained
within DDP Segments may be Placed directly into its final
destination in memory without processing of the ULP. This may
occur even when the DDP Segments arrive out of order. Out of
order Placement support may require the Data Sink to implement
the LLP and DDP as one functional block.
Direct Data Placement Protocol (DDP) - Also, a wire protocol that
supports Direct Data Placement by associating explicit memory
buffer placement information with the LLP payload units.
Message Offset (MO) - For the DDP Untagged Buffer Model, specifies
the offset, in bytes, from the start of a DDP Message.
Message Sequence Number (MSN) - For the DDP Untagged Buffer Model,
specifies a sequence number that is increasing with each DDP
Message.
Queue Number (QN) - For the DDP Untagged Buffer Model, identifies
a destination Data Sink queue for a DDP Segment.
Steering Tag - An identifier of a Tagged Buffer on a Node, valid
as defined within a protocol specification.
STag - Steering Tag
Tagged Buffer - A buffer that is explicitly Advertised to the
Remote Peer through exchange of an STag, Tagged Offset, and
length.
Tagged Buffer Model - A DDP data transfer model used to transfer
Tagged Buffers from the Local Peer to the Remote Peer.
Tagged DDP Message - A DDP Message that targets a Tagged Buffer.
Tagged Offset (TO) - The offset within a Tagged Buffer on a Node.
Untagged Buffer - A buffer that is not explicitly Advertised to
the Remote Peer. Untagged buffers support one of the two
available data transfer mechanisms called the Untagged Buffer
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Model. An untagged buffer is used to send asynchronous control
messages to the Remote Peer for RDMA Read, Send, and Terminate
requests. Untagged Buffers handle Untagged DDP Messages.
Untagged Buffer Model - A DDP data transfer model used to transfer
Untagged Buffers from the Local Peer to the Remote Peer.
Untagged DDP Message - A DDP Message that targets an Untagged
Buffer.
2.4 Remote Direct Memory Access (RDMA)
Event - An indication provided by the RDMAP Layer to the ULP to
indicate a Completion or other condition requiring immediate
attention.
Invalidate STag - A mechanism used to prevent the Remote Peer from
reusing a previous explicitly Advertised STag, until the Local
Peer makes it available through a subsequent explicit
Advertisement. The STag cannot be accessed remotely until it
is explicit Advertised again.
RDMA Completion (Completion, Completed, Complete, Completes) - For
RDMA, Completion is defined as the process of informing the
ULP that a particular RDMA Operation has performed all
functions specified for the RDMA Operations, including
Placement and Delivery. The Completion semantic of each RDMA
Operation is distinctly defined.
RDMA Message - A data transfer mechanism used to fulfill an RDMA
Operation.
RDMA Operation - A sequence of RDMA Messages, including control
Messages, to transfer data from a Data Source to a Data Sink.
The following RDMA Operations are defined - RDMA Writes, RDMA
Read, Send, Send with Invalidate, Send with Solicited Event,
Send with Solicited Event and Invalidate, and Terminate.
RDMA Protocol (RDMAP) - A wire protocol that supports RDMA
Operations to transfer ULP data between a Local Peer and the
Remote Peer.
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RDMAP Abortive Termination (Termination, Terminated, Terminate,
Terminates) - The act of closing an RDMAP Stream without
attempting to Complete in-progress and pending RDMA
Operations.
RDMAP Graceful Termination - The act of closing an RDMAP Stream
such that all in-progress and pending RDMA Operations are
allowed to Complete successfully.
RDMA Read - An RDMA Operation used by the Data Sink to transfer
the contents of a source RDMA buffer from the Remote Peer to
the Local Peer. An RDMA Read operation consists of a single
RDMA Read Request Message and a single RDMA Read Response
Message.
RDMA Read Request - An RDMA Message used by the Data Sink to
request the Data Source to transfer the contents of an RDMA
buffer. The RDMA Read Request Message describes both the Data
Source and Data Sink RDMA buffers.
RDMA Read Request Queue - The queue used for processing RDMA Read
Requests. The RDMA Read Request Queue has a DDP Queue Number
of 1.
RDMA Read Response - An RDMA Message used by the Data Source to
transfer the contents of an RDMA buffer to the Data Sink, in
response to an RDMA Read Request. The RDMA Read Response
Message only describes the data sink RDMA buffer.
RDMAP Stream - An association between a pair of RDMAP
implementations, possibly on different Nodes, which transfer
ULP data using RDMA Operations. There may be multiple RDMAP
Streams on a single Node. An RDMAP Stream maps directly to a
single DDP Stream.
RDMA Write - An RDMA Operation that transfers the contents of a
source RDMA Buffer from the Local Peer to a destination RDMA
Buffer at the Remote Peer using RDMA. The RDMA Write Message
only describes the Data Sink RDMA buffer.
Remote Direct Memory Access (RDMA) - A method of accessing memory
on a remote system in which the local system specifies the
remote location of the data to be transferred. Employing a
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RNIC in the remote system allows the access to take place
without interrupting the processing of the CPU(s) on the
system.
Send - An RDMA Operation that transfers the contents of a ULP
Buffer from the Local Peer to an Untagged Buffer at the Remote
Peer.
Send Message Type - A Send Message, Send with Invalidate Message,
Send with Solicited Event Message, or Send with Solicited
Event and Invalidate Message.
Send Operation Type - A Send Operation, Send with Invalidate
Operation, Send with Solicited Event Operation, or Send with
Solicited Event and Invalidate Operation.
Solicited Event (SE) - A facility by which an RDMA Operation
sender may cause an Event to be generated at the recipient, if
the recipient is configured to generate such an Event, when a
Send with Solicited Event or Send with Solicited Event and
Invalidate Message is received. Note: The Local Peer's ULP
can use the Solicited Event mechanism to ensure that Messages
designated as important to the ULP are handled in an
expeditious manner by the Remote Peer's ULP. The ULP at the
Local Peer can indicate a given Send Message Type is important
by using the Send with Solicited Event Message or Send with
Solicited Event and Invalidate Message. The ULP at the Remote
Peer can choose to only be notified when valid Send with
Solicited Event Messages and/or Send with Solicited Event and
Invalidate Messages arrive and handle other valid incoming
Send Messages or Send with Invalidate Messages at its leisure.
Terminate - An RDMA Message used by a Node to pass an error
indication to the peer Node on an RDMAP Stream. This operation
is for RDMAP use only.
ULP Buffer - A buffer owned above the RDMAP Layer and advertised
to the RDMAP Layer either as a Tagged Buffer or an Untagged
ULP Buffer.
ULP Message - The ULP data that is handed to a specific protocol
layer for transmission. Data boundaries are preserved as they
are transmitted through iWARP.
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3 ULP and Transport Attributes
3.1 Transport Requirements & Assumptions
RDMAP MUST be layered on top of the Direct Data Placement Protocol
[DDP].
RDMAP requires the following DDP support:
* RDMAP uses three queues for Untagged Buffers:
* Queue Number 0 (used by RDMAP for Send, Send with
Invalidate, Send with Solicited Event, and Send with
Solicited Event and Invalidate operations).
* Queue Number 1 (used by RDMAP for RDMA Read operations).
* Queue Number 2 (used by RDMAP for Terminate operations).
* DDP maps a single RDMA Message to a single DDP Message.
* DDP uses the STag and Tagged Offset provided by the RDMAP for
Tagged Buffer Messages (i.e., RDMA Write and RDMA Read
Response).
* When the DDP layer Delivers an Untagged DDP Message to the
RDMAP layer, DDP provides the length of the DDP Message. This
ensures that RDMAP does not have to carry a length field in its
header.
* When the RDMAP layer provides an RDMA Message to the DDP Layer,
DDP must insert the RsvdULP field value provided by the RDMAP
Layer into the associated DDP Message.
* When the DDP layer Delivers a DDP Message to the RDMAP layer,
DDP provides the RsvdULP field.
* The RsvdULP field must be 1 octet for DDP Tagged Messages and 5
octets for DDP Untagged Messages.
* DDP propagates to RDMAP all operation or protection errors
(used by RDMAP Terminate) and, when appropriate, the DDP Header
fields of the DDP Segment that encountered the error.
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* If an RDMA Operation is aborted by DDP or a lower layer, the
contents of the Data Sink buffers associated with the operation
are considered indeterminate.
* DDP in conjunction with the lower layers provide reliable, in-
order Delivery.
3.2 RDMAP Interactions with the ULP
RDMAP provides the ULP with access to the following RDMA
Operations as defined in this specification:
* Send
* Send with Solicited Event
* Send with Invalidate
* Send with Solicited Event and Invalidate
* RDMA Write
* RDMA Read
For Send Operation Types, the following are the interactions
between the RDMAP Layer and the ULP:
* At the Data Source:
* The ULP passes to the RDMAP Layer the following:
* ULP Message Length
* ULP Message
* An indication of the Send Operation Type, where the
valid types are: Send, Send with Solicited Event, Send
with Invalidate, or Send with Solicited Event and
Invalidate.
* An Invalidate STag, if the Send Operation Type was
Send with Invalidate or Send with Solicited Event and
Invalidate.
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* When the Send Operation Type Completes, an indication of
the Completion results.
* At the Data Sink:
* If the Send Operation Type Completed successfully, the
RDMAP Layer passes the following information to the ULP
Layer:
* ULP Message Length
* ULP Message
* An Event, if the Data Sink is configured to generate
an Event.
* An Invalidated STag, if the Send Operation Type was
Send with Invalidate or Send with Solicited Event and
Invalidate.
* If the Send Operation Type Completed in error, the Data
Sink RDMAP Layer will pass up the corresponding error
information to the Data Sink ULP and send a Terminate
Message to the Data Source RDMAP Layer. The Data Source
RDMAP Layer will then pass up the Terminate Message to the
ULP.
For RDMA Write Operations, the following are the interactions
between the RDMAP Layer and the ULP:
* At the Data Source:
* The ULP passes to the RDMAP Layer the following:
* ULP Message Length
* ULP Message
* Data Sink STag
* Data Sink Tagged Offset
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* When the RDMA Write Operation Completes, an indication of
the Completion results.
* At the Data Sink:
* If the RDMA Write completed successfully, the RDMAP Layer
does not Deliver the RDMA Write to the ULP. It does Place
the ULP Message transferred through the RDMA Write Message
into the ULP Buffer.
* If the RDMA Write completed in error, the Data Sink RDMAP
Layer will pass up the corresponding error information to
the Data Sink ULP and send a Terminate Message to the Data
Source RDMAP Layer. The Data Source RDMAP Layer will then
pass up the Terminate Message to the ULP.
For RDMA Read Operations, the following are the interactions
between the RDMAP Layer and the ULP:
* At the Data Sink:
* The ULP passes to the RDMAP Layer the following:
* ULP Message Length
* Data Source STag
* Data Sink STag
* Data Source Tagged Offset
* Data Sink Tagged Offset
* When the RDMA Read Operation Completes, an indication of
the Completion results.
* At the Data Source:
* If no error occurred while processing the RDMA Read
Request, the Data Source will not pass up any information
to the ULP.
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* If an error occurred while processing the RDMA Read
Request, the Data Source RDMAP Layer will pass up the
corresponding error information to the Data Source ULP and
send a Terminate Message to the Data Sink RDMAP Layer. The
Data Sink RDMAP Layer will then pass up the Terminate
Message to the ULP.
For STags made available to the RDMAP Layer, following are the
interactions between the RDMAP Layer and the ULP:
* If the ULP enables an STag, the ULP passes to the RDMAP Layer
the:
* STag;
* range of Tagged Offsets that are associated with a given
STag;
* remote access rights (read, write, or read and write)
associated with a given, valid STag; and
* association between a given STag and a given RDMAP Stream.
* If the ULP disables an STag, the ULP passes to the RDMAP Layer
the STag.
If an error occurs at the RDMAP Layer, the RDMAP Layer may pass
back error information (e.g., the content of a Terminate Message)
to the ULP.
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4 Header Format
The control information of RDMA Messages is included in DDP
protocol defined header fields, with the following exceptions:
* The first octet reserved for ULP usage on all DDP Messages in
the DDP Protocol (i.e., the RsvdULP Field) is used by RDMAP to
carry the RDMA Message Opcode and the RDMAP version. This octet
is known as the RDMAP Control Field in this specification. For
Send with Invalidate and Send with Solicited Event and
Invalidate, RDMAP uses the second through fifth octets provided
by DDP on Untagged DDP Messages to carry the STag that will be
Invalidated.
* The RDMA Message length is passed by the RDMAP layer to the DDP
layer on all outbound transfers.
* For RDMA Read Request Messages, the RDMA Read Message Size is
included in the RDMA Read Request Header.
* The RDMA Message length is passed to the RDMAP Layer by the DDP
layer on inbound Untagged Buffer transfers.
* Two RDMA Messages carry additional RDMAP headers. The RDMA Read
Request carries the Data Sink and Data Source buffer
descriptions, including buffer length. The Terminate carries
additional information associated with the error that caused
the Terminate.
4.1 RDMAP Control and Invalidate STag Field
The version of RDMAP defined by this specification uses all 8 bits
of the RDMAP Control Field. The first octet reserved for ULP use
in the DDP Protocol MUST be used by the RDMAP to carry the RDMAP
Control Field. The ordering of the bits in the first octet MUST be
as defined in Figure 3 DDP Control, RDMAP Control, and Invalidate
STag Field. For Send with Invalidate and Send with Solicited Event
and Invalidate, the second through fifth octets of the DDP RsvdULP
field MUST be used by RDMAP to carry the Invalidate STag. Figure 3
DDP Control, RDMAP Control, and Invalidate STag Field depicts the
format of the DDP Control and RDMAP Control fields. (Note: In
Figure 3 DDP Control, RDMAP Control, and Invalidate STag Field,
the DDP Header is offset by 16 bits to accommodate the MPA header
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defined in [MPA]. The MPA header is only present if DDP is layered
on top of MPA.)
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|T|L| Resrv | DV| RV|Rsv| Opcode|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Invalidate STag |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3 DDP Control, RDMAP Control, and Invalidate STag Fields
All RDMA Messages handed by the RDMAP Layer to the DDP layer MUST
define the value of the Tagged flag in the DDP Header. Figure 4
RDMA Usage of DDP Fields MUST be used to define the value of the
Tagged flag that is handed to the DDP Layer for each RDMA Message.
Figure 4 RDMA Usage of DDP Fields defines the value of the RDMA
Opcode field that MUST be used for each RDMA Message.
Figure 4 RDMA Usage of DDP Fields defines when the STag, Queue
Number, and Tagged Offset fields MUST be provided for each RDMA
Message.
For this version of the RDMAP, all RDMA Messages MUST have:
* Bits 24-25; RDMA Version field: 01b for an RNIC that complies
with this RDMA protocol specification. 00b for an RNIC that
complies with the RDMA Consortium's RDMA protocol
specification. Both version numbers are valid.
Interoperability is dependent on MPA protocol version
negotiation (e.g., MPA marker and MPA CRC).
* Bits 26-27; Reserved. MUST be set to zero by sender, ignored by
the receiver.
* Bits 28-31; OpCode field: see Figure 4 RDMA Usage of DDP
Fields.
* Bits 32-63; Invalidate STag. However, this field is only valid
for Send with Invalidate and Send with Solicited Event and
Invalidate Messages (see Figure 4 RDMA Usage of DDP Fields).
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For Send, Send with Solicited Event, RDMA Read Request, and
Terminate, the Invalidate STag field MUST be set to zero on
transmit and ignored by the receiver.
-------+-----------+-------+------+-------+-----------+--------------
RDMA | Message | Tagged| STag | Queue | Invalidate| Message
Message| Type | Flag | and | Number| STag | Length
OpCode | | | TO | | | Communicated
| | | | | | between DDP
| | | | | | and RDMAP
-------+-----------+-------+------+-------+-----------+--------------
0000b | RDMA Write| 1 | Valid| N/A | N/A | Yes
| | | | | |
-------+-----------+-------+------+-------+-----------+--------------
0001b | RDMA Read | 0 | N/A | 1 | N/A | Yes
| Request | | | | |
-------+-----------+-------+------+-------+-----------+--------------
0010b | RDMA Read | 1 | Valid| N/A | N/A | Yes
| Response | | | | |
-------+-----------+-------+------+-------+-----------+--------------
0011b | Send | 0 | N/A | 0 | N/A | Yes
| | | | | |
-------+-----------+-------+------+-------+-----------+--------------
0100b | Send with | 0 | N/A | 0 | Valid | Yes
| Invalidate| | | | |
-------+-----------+-------+------+-------+-----------+--------------
0101b | Send with | 0 | N/A | 0 | N/A | Yes
| SE | | | | |
-------+-----------+-------+------+-------+-----------+--------------
0110b | Send with | 0 | N/A | 0 | Valid | Yes
| SE and | | | | |
| Invalidate| | | | |
-------+-----------+-------+------+-------+-----------+--------------
0111b | Terminate | 0 | N/A | 2 | N/A | Yes
| | | | | |
-------+-----------+-------+------+-------+-----------+--------------
1000b | |
to | Reserved | Not Specified
1111b | |
-------+-----------+-------------------------------------------------
Figure 4 RDMA Usage of DDP Fields
Note: N/A means Not Applicable.
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4.2 RDMA Message Definitions
The following figure defines which RDMA Headers MUST be used on
each RDMA Message and which RDMA Messages are allowed to carry ULP
payload:
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-------+-----------+-------------------+-------------------------
RDMA | Message | RDMA Header Used | ULP Message allowed in
Message| Type | | the RDMA Message
OpCode | | |
| | |
-------+-----------+-------------------+-------------------------
0000b | RDMA Write| None | Yes
| | |
-------+-----------+-------------------+-------------------------
0001b | RDMA Read | RDMA Read Request | No
| Request | Header |
-------+-----------+-------------------+-------------------------
0010b | RDMA Read | None | Yes
| Response | |
-------+-----------+-------------------+-------------------------
0011b | Send | None | Yes
| | |
-------+-----------+-------------------+-------------------------
0100b | Send with | None | Yes
| Invalidate| |
-------+-----------+-------------------+-------------------------
0101b | Send with | None | Yes
| SE | |
-------+-----------+-------------------+-------------------------
0110b | Send with | None | Yes
| SE and | |
| Invalidate| |
-------+-----------+-------------------+-------------------------
0111b | Terminate | Terminate Header | No
| | |
-------+-----------+-------------------+-------------------------
1000b | |
to | Reserved | Not Specified
1111b | |
-------+-----------+-------------------+-------------------------
Figure 5 RDMA Message Definitions
4.3 RDMA Write Header
The RDMA Write Message does not include an RDMAP header. The RDMAP
layer passes to the DDP layer an RDMAP Control Field. The RDMA
Write Message is fully described by the DDP Headers of the DDP
Segments associated with the Message.
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See section 11 Appendix for a description of the DDP Segment
format associated with RDMA Write Messages.
4.4 RDMA Read Request Header
The RDMA Read Request Message carries an RDMA Read Request Header
that describes the Data Sink and Data Source Buffers used by the
RDMA Read operation. The RDMA Read Request Header immediately
follows the DDP header. The RDMAP layer passes to the DDP layer an
RDMAP Control Field. The following figure depicts the RDMA Read
Request Header that MUST be used for all RDMA Read Request
Messages:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Sink STag (SinkSTag) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Data Sink Tagged Offset (SinkTO) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RDMA Read Message Size (RDMARDSZ) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Source STag (SrcSTag) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Data Source Tagged Offset (SrcTO) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6 RDMA Read Request Header Format
Data Sink Steering Tag: 32 bits.
The Data Sink Steering Tag identifies the Data Sink's Tagged
Buffer. This field MUST be copied, without interpretation,
from the RDMA Read Request into the corresponding RDMA Read
Response and allows the Data Sink to place the returning
data. The STag is associated with the RDMAP Stream through a
mechanism that is outside the scope of the RDMAP
specification.
Data Sink Tagged Offset: 64 bits.
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The Data Sink Tagged Offset specifies the starting offset, in
octets, from the base of the Data Sink's Tagged Buffer, where
the data is to be written by the Data Source. This field is
copied from the RDMA Read Request into the corresponding RDMA
Read Response and allows the Data Sink to place the returning
data. The Data Sink Tagged Offset MAY start at an arbitrary
offset.
The Data Sink STag and Data Sink Tagged Offset fields
describe the buffer to which the RDMA Read data is written.
Note: the DDP Layer protects against a wrap of the Data Sink
Tagged Offset.
RDMA Read Message Size: 32 bits.
The RDMA Read Message Size is the amount of data, in octets,
read from the Data Source. A single RDMA Read Request Message
can retrieve from 0 to 2^32-1 data octets from the Data
Source.
Data Source Steering Tag: 32 bits.
The Data Source Steering Tag identifies the Data Source's
Tagged Buffer. The STag is associated with the RDMAP Stream
through a mechanism that is outside the scope of the RDMAP
specification.
Data Source Tagged Offset: 64 bits.
The Tagged Offset specifies the starting offset, in octets,
that is to be read from the Data Source's Tagged Buffer. The
Data Source Tagged Offset MAY start at an arbitrary offset.
The Data Source STag and Data Source Tagged Offset fields
describe the buffer from which the RDMA Read data is read.
See Section 7.2 Errors Detected at the Remote Peer on Incoming
RDMA Messages for a description of error checking required upon
processing of an RDMA Read Request at the Data Source.
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4.5 RDMA Read Response Header
The RDMA Read Response Message does not include an RDMAP header.
The RDMAP layer passes to the DDP layer an RDMAP Control Field.
The RDMA Read Response Message is fully described by the DDP
Headers of the DDP Segments associated with the Message.
See Section 11 Appendix for a description of the DDP Segment
format associated with RDMA Read Response Messages.
4.6 Send Header and Send with Solicited Event Header
The Send and Send with Solicited Event Message do not include an
RDMAP header. The RDMAP layer passes to the DDP layer an RDMAP
Control Field. The Send and Send with Solicited Event Message are
fully described by the DDP Headers of the DDP Segments associated
with the Message.
See Section 11 Appendix for a description of the DDP Segment
format associated with Send and Send with Solicited Event
Messages.
4.7 Send with Invalidate Header and Send with SE and Invalidate
Header
The Send with Invalidate and Send with Solicited Event and
Invalidate Message do not include an RDMAP header. The RDMAP layer
passes to the DDP layer an RDMAP Control Field and the Invalidate
STag field (see section 4.1 RDMAP Control and Invalidate STag
Field). The Send with Invalidate and Send with Solicited Event and
Invalidate Message are fully described by the DDP Headers of the
DDP Segments associated with the Message.
See Section 11 Appendix for a description of the DDP Segment
format associated with Send and Send with Solicited Event
Messages.
4.8 Terminate Header
The Terminate Message carries a Terminate Header that contains
additional information associated with the cause of the Terminate.
The Terminate Header immediately follows the DDP header. The RDMAP
layer passes to the DDP layer an RDMAP Control Field. The
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following figure depicts a Terminate Header that MUST be used for
the Terminate Message:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Terminate Control | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DDP Segment Length (if any) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
// //
| Terminated DDP Header (if any) |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// //
| Terminated RDMA Header (if any) |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7 Terminate Header Format
Terminate Control: 19 bits.
The Terminate Control field MUST have the format defined in
Figure 8 Terminate Control Field.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Layer | EType | Error Code |HdrCt|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8 Terminate Control Field
* Figure 9 Terminate Control Field Values defines the valid
values that MUST be used for this field.
* Layer: 4 bits.
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Identifies the layer that encountered the error.
* EType (RDMA Error Type): 4 bits.
Identifies the type of error that caused the
Terminate. When the error is detected at the RDMAP
Layer, the RDMAP Layer inserts the Error Type into
this field. When the error is detected at a LLP layer,
a LLP layer creates the Error Type and the DDP layer
passes it up to the RDMAP Layer, and the RDMAP Layer
inserts it into this field.
* Error Code: 8 bits.
This field identifies the specific error that caused
the Terminate. When the error is detected at the RDMAP
Layer, the RDMAP Layer creates the Error Code. When
the error is detected at a LLP layer, a LLP layer
creates the Error Code and the DDP layer passes it up
to the RDMAP Layer, and the RDMAP Layer inserts it
into this field.
* HdrCt: 3 bits.
Header control bits:
* M: bit 16. DDP Segment Length valid. See Figure 10
for when this bit SHOULD be set.
* D: bit 17. DDP Header Included. See Figure 10 for
when this bit SHOULD be set.
* R: bit 18. RDMAP Header Included. See Figure 10
for when this bit SHOULD be set.
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-------+----------+-------+-------------+------+--------------------
Layer | Layer | Error | Error Type | Error| Error Code Name
| Name | Type | Name | Code |
-------+----------+-------+-------------+------+--------------------
| | 0000b | Local | None | None - This error
| | | Catastrophic| | type does not have
| | | Error | | an error code. Any
| | | | | value in this field
| | | | | is acceptable.
| +-------+-------------+------+--------------------
| | | | 00X | Invalid STag
| | | +------+--------------------
| | | | 01X | Base or bounds
| | | | | violation
| | | Remote +------+--------------------
| | 0001b | Protection | 02X | Access rights
| | | Error | | violation
| | | +------+--------------------
0000b | RDMA | | | 03X | STag not associated
| | | | | with RDMAP Stream
| | | +------+--------------------
| | | | 04X | TO wrap
| | | +------+--------------------
| | | | 09X | STag cannot be
| | | | | Invalidated
| | | +------+--------------------
| | | | FFX | Unspecified Error
| +-------+-------------+------+--------------------
| | | | 05X | Invalid RDMAP
| | | | | version
| | | +------+--------------------
| | | | 06X | Unexpected OpCode
| | | Remote +------+--------------------
| | 0010b | Operation | 07X | Catastrophic error,
| | | Error | | localized to RDMAP
| | | | | Stream
| | | +------+--------------------
| | | | 08X | Catastrophic error,
| | | | | global
| | | +------+--------------------
| | | | 09X | STag cannot be
| | | | | Invalidated
| | | +------+--------------------
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| | | | FFX | Unspecified Error
-------+----------+-------+-------------+------+--------------------
0001b | DDP | See DDP Specification [DDP] for a description of
| | the values and names.
-------+----------+-------+-----------------------------------------
0010b | LLP | For MPA, see MPA Specification [MPA] for a
| (eg MPA) | description of the values and names.
-------+----------+-------+-----------------------------------------
Figure 9 Terminate Control Field Values
Reserved: 13 bits. This field MUST be set to zero on transmit,
ignored on receive.
DDP Segment Length: 16 bits
The length handed up by the DDP Layer when the error was
detected. It MUST be valid if the M bit is set. It MUST be
present when the D bit is set.
Terminated DDP Header: 112 bits for Tagged Messages and 144 bits
for Untagged Messages.
The DDP Header of the incoming Message that is associated
with the Terminate. The DDP Header is not present if the
Terminate Error Type is a Local Catastrophic Error. It MUST
be present if the D bit is set.
Terminated RDMA Header: 224 bits.
The Terminated RDMA Header is only sent back if the terminate
is associated with an RDMA Read Request Message. It MUST be
present if the R bit is set.
If the terminate occurs before the first RDMA Read Request
byte is processed, the original RDMA Read Request Header is
sent back.
If the terminate occurs after the first RDMA Read Request
byte is processed, the RDMA Read Request Header is updated to
reflect the current location of the RDMA Read operation that
is in process:
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* Data Sink STag = Data Sink STag originally sent in the
RDMA Read Request.
* Data Sink Tagged Offset = Current offset into the Data
Sink Tagged Buffer. For example if the RDMA Read
Request was terminated after 2048 octets were sent,
then the Data Sink Tagged Offset = the original Data
Sink Tagged Offset + 2048.
* Data Message size = Number of bytes left to transfer.
* Data Source STag = Data Source STag in the RDMA Read
Request.
* Data Source Tagged Offset = Current offset into the
Data Source Tagged Buffer. For example if the RDMA
Read Request was terminated after 2048 octets were
sent, then the Data Source Tagged Offset = the
original Data Source Tagged Offset + 2048.
Note: if a given LLP does not define any termination codes for the
RDMAP Termination message to use, then none would be used for that
LLP.
Figure 10 Error Type to RDMA Message Mapping maps layer name and
error types to each RDMA Message type:
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---------+-------------+------------+------------+-----------------
Layer | Error Type | Terminate | Terminate | What type of
Name | Name | Includes | Includes | RDMA Message can
| | DDP Header | RDMA Header| cause the error
| | and DDP | |
| | Segment | |
| | Length | |
---------+-------------+------------+------------+-----------------
| Local | No | No | Any
| Catastrophic| | |
| Error | | |
+-------------+------------+------------+-----------------
| Remote | Yes, if | Yes | Only RDMA Read
RDMA | Protection | possible | | Request, Send
| Error | | | with Invalidate,
| | | | and Send with SE
| | | | and Invalidate
+-------------+------------+------------+-----------------
| Remote | Yes, if | No | Any
| Operation | possible | |
| Error | | |
---------+-------------+------------+------------+-----------------
DDP | See DDP Spec| Yes | No | Any
| [DDP] | | |
---------+-------------+------------+------------+-----------------
LLP | See LLP Spec| No | No | Any
| [e.g., MPA] | | |
Figure 10 Error Type to RDMA Message Mapping
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5 Data Transfer
5.1 RDMA Write Message
An RDMA Write is used by the Data Source to transfer data to a
previously Advertised Tagged Buffer at the Data Sink. The RDMA
Write Message has the following semantics:
* An RDMA Write Message MUST reference a Tagged Buffer. That is,
the Data Source RDMAP Layer MUST request that the DDP layer
mark the Message as Tagged.
* A valid RDMA Write Message MUST NOT be delivered to the Data
Sink's ULP (i.e., it is placed by the DDP layer).
* At the Remote Peer, when an invalid RDMA Write Message is
delivered to the Remote Peer's RDMAP Layer, an error is
surfaced (see section 7.1 RDMAP Error Surfacing).
* The Tagged Offset of a Tagged Buffer MAY start at a non-zero
value.
* An RDMA Write Message MAY target all or part of a previously
Advertised buffer.
* The RDMAP does not define how the buffer(s) used by an outbound
RDMA Write is defined and how it is addressed. For example, an
implementation of RDMA may choose to allow a gather-list of
non-contiguous data blocks to be the source of an RDMA Write.
In this case, the data blocks would be combined by the Data
Source and sent as a single RDMA Write Message to the Data
Sink.
* The Data Source RDMAP Layer MUST issue RDMA Write Messages to
the DDP layer in the order they were submitted by the ULP.
* At the Data Source, a subsequent Send (Send with Invalidate,
Send with Solicited Event, or Send with Solicited Event and
Invalidate) Message MAY be used to signal Delivery of previous
RDMA Write Messages to the Data Sink, if desired by the ULP.
* If the Local Peer wishes to write to multiple Tagged Buffers on
the Remote Peer, the Local Peer MUST use multiple RDMA Write
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Messages. That is, a single RDMA Write Message can only write
to one remote Tagged Buffer.
* The Data Source MAY issue a zero length RDMA Write Message.
5.2 RDMA Read Operation
The RDMA Read operation MUST consist of a single RDMA Read Request
Message and a single RDMA Read Response Message.
5.2.1 RDMA Read Request Message
An RDMA Read Request is used by the Data Sink to transfer data
from a previously Advertised Tagged Buffer at the Data Source to a
Tagged Buffer at the Data Sink. The RDMA Read Request Message has
the following semantics:
* An RDMA Read Request Message MUST reference an Untagged Buffer.
That is, the Local Peer's RDMAP Layer MUST request that the DDP
mark the Message as Untagged.
* One RDMA Read Request Message MUST consume one Untagged Buffer.
* The Remote Peer's RDMAP Layer MUST process an RDMA Read Request
Message. A valid RDMA Read Request Message MUST NOT be
delivered to the Data Sink's ULP (i.e., it is processed by the
RDMAP layer).
* At the Remote Peer, when an invalid RDMA Read Request Message
is delivered to the Remote Peer's RDMAP Layer, an error is
surfaced (see section 7.1 RDMAP Error Surfacing).
* AN RDMA Read Request Message MUST reference the RDMA Read
Request Queue. That is, the Local Peer's RDMAP Layer MUST
request that the DDP layer set the Queue Number field to one.
* The Local Peer MUST pass to the DDP Layer RDMA Read Request
Messages in the order they were submitted by the ULP.
* The Remote Peer MUST process the RDMA Read Request Messages in
the order they were sent.
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* If the Local Peer wishes to read from multiple Tagged Buffers
on the Remote Peer, the Local Peer MUST use multiple RDMA Read
Request Messages. That is, a single RDMA Read Request Message
MUST only read from one remote Tagged Buffer.
* AN RDMA Read Request Message MAY target all or part of a
previously Advertised buffer.
* If the Data Source receives a valid RDMA Read Request Message
it MUST respond with a valid RDMA Read Response Message.
* The Data Sink MAY issue a zero length RDMA Read Request
Message, by setting the RDMA Read Message Size field to zero in
the RDMA Read Request Header.
* If the Data Source receives a non-zero length RDMA Read Message
Size, the Data Source RDMAP MUST validate the Data Source STag
and Data Source Tagged Offset contained in the RDMA Read
Request Header.
* If the Data Source receives an RDMA Read Request Header with
the RDMA Read Message Size set to zero, the Data Source RDMAP:
* MUST NOT validate the Data Source STag and Data Source
Tagged Offset contained in the RDMA Read Request Header,
and
* MUST respond with a zero length RDMA Read Response
Message.
5.2.2 RDMA Read Response Message
The RDMA Read Response Message uses the DDP Tagged Buffer Model to
Deliver the contents of a previously requested Data Source Tagged
Buffer to the Data Sink, without any involvement from the ULP at
the Remote Peer. The RDMA Read Response Message has the following
semantics:
* The RDMA Read Response Message for the associated RDMA Read
Request Message travels in the opposite direction.
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* An RDMA Read Response Message MUST reference a Tagged Buffer.
That is, the Data Source RDMAP Layer MUST request that the DDP
mark the Message as Tagged.
* The Data Source MUST ensure that a sufficient number of
Untagged Buffers are available on the RDMA Read Request Queue
(Queue with DDP Queue Number 1) to support the maximum number
of RDMA Read Requests negotiated by the ULP.
* The RDMAP Layer MUST Deliver the RDMA Read Response Message to
the ULP.
* At the Remote Peer, when an invalid RDMA Read Response Message
is delivered to the Remote Peer's RDMAP Layer, an error is
surfaced (see section 7.1 RDMAP Error Surfacing).
* The Tagged Offset of a Tagged Buffer MAY start at a non-zero
value.
* The Data Source RDMAP Layer MUST pass RDMA Read Response
Messages to the DDP layer in the order that the RDMA Read
Request Messages were received by the RDMAP Layer at the Data
Source.
* The Data Sink MAY validate that the STag, Tagged Offset, and
length of the RDMA Read Response Message are the same as the
STag, Tagged Offset, and length included in the corresponding
RDMA Read Request Message.
* A single RDMA Read Response Message MUST write to one remote
Tagged Buffer. If the Data Sink wishes to Read multiple Tagged
Buffers, the Data Sink can use multiple RDMA Read Request
Messages.
5.3 Send Message Type
The Send Message Type uses the DDP Untagged Buffer Model to
transfer data from the Data Source into an Untagged Buffer at the
Data Sink.
* A Send Message Type MUST reference an Untagged Buffer. That is,
the Local Peer's RDMAP Layer MUST request that the DDP layer
mark the Message as Untagged.
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* One Send Message Type MUST consume one Untagged Buffer.
* The ULP Message sent using a Send Message Type MAY be less
than or equal to the size of the consumed Untagged Buffer.
The RDMAP Layer communicates to the ULP the size of the
data written into the Untagged Buffer.
* If the ULP Message sent via Send Message Type is larger
than the Data Sink's Untagged Buffer, it is an error (see
section 9.1 RDMAP Error Surfacing).
* At the Remote Peer, the Send Message Type MUST be Delivered to
the Remote Peer's ULP in the order they were sent.
* After the Send with Solicited Event or Send with Solicited
Event and Invalidate Message is Delivered to the ULP, the RDMAP
MAY generate an Event, if the Data Sink is configured to
generate such an Event.
* At the Remote Peer, when an invalid Send Message Type is
Delivered to the Remote Peer's RDMAP Layer, an error is
surfaced (see section 7.1 RDMAP Error Surfacing).
* The RDMAP does not define how the buffer(s) used by an outbound
Send Message Type is defined and how it is addressed. For
example, an implementation of RDMA may choose to allow a
gather-list of non-contiguous data blocks to be the source of a
Send Message Type. In this case, the data blocks would be
combined by the Data Source and sent as a single Send Message
Type to the Data Sink.
* For a Send Message Type, the Local Peer's RDMAP Layer MUST
request that the DDP layer set the Queue Number field to zero.
* The Local Peer MUST issue Send Message Type Messages in the
order they were submitted by the ULP.
* The Data Source MAY pass a zero length Send Message Type. A
zero length Send Message Type MUST consume an Untagged Buffer
at the Data Sink. A Send with Invalidate or Send with Solicited
Event and Invalidate Message MUST reference an STag. That is,
the Local Peer's RDMAP Layer MUST pass the RDMA control field
and the STag that will be Invalidated to the DDP layer.
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* When the Send with Invalidate and Send with Solicited Event and
Invalidate Message are Delivered to the Remote Peer's RDMAP
Layer, the RDMAP Layer MUST:
* Verify the STag that is associated with the RDMAP Stream;
and
* Invalidate the STag if it is associated with the RDMAP
Stream; or Issue a Terminate Message with the STag Cannot
be Invalidated Terminate Error Code, if the STag is not
associated with the RDMAP Stream.
5.4 Terminate Message
The Terminate Message uses the DDP Untagged Buffer Model to
transfer error related information from the Data Source into an
Untagged Buffer at the Data Sink and then ceases all further
communications on the underlying DDP Stream. The Terminate Message
has the following semantics:
* A Terminate Message MUST reference an Untagged Buffer. That is,
the Local Peer's RDMAP Layer MUST request that the DDP layer
mark the Message as Untagged.
* A Terminate Message references the Terminate Queue. That is,
the Local Peer's RDMAP Layer MUST request that the DDP layer
set the Queue Number field to two.
* One Terminate Message MUST consume one Untagged Buffer.
* On a single RDMAP Stream, the RDMAP layer MUST guarantee
placement of a single Terminate Message.
* A Terminate Message MUST be Delivered to the Remote Peer's
RDMAP Layer. The RDMAP Layer MUST Deliver the Terminate Message
to the ULP.
* At the Remote Peer, when an invalid Terminate Message is
delivered to the Remote Peer's RDMAP Layer, an error is
surfaced (see section 7.1 RDMAP Error Surfacing).
* The RDMAP Layer Completes in error all ULP Operations that have
not been provided to the DDP layer.
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* After sending a Terminate Message on an RDMAP Stream, the Local
Peer MUST NOT send any more Messages on that specific RDMAP
Stream.
* After receiving a Terminate Message on an RDMAP Stream, the
Remote Peer MAY stop sending Messages on that specific RDMAP
Stream.
5.5 Ordering and Completions
It is important to understand the difference between Placement and
Delivery ordering since RDMAP provides quite different semantics
for the two.
Note that many current protocols, both as used in the Internet and
elsewhere, assume that data is both Placed and Delivered in order.
This allowed applications to take a variety of shortcuts by taking
advantage of this fact. For RDMAP, many of these shortcuts are no
longer safe to use, and could cause application failure.
The following rules apply to implementations of the RDMAP
protocol. Note, in these rules Send includes Send, Send with
Invalidate, Send with Solicited Event, and Send with Solicited
Event and Invalidate:
1. RDMAP does not provide ordering among Messages on different
RDMAP Streams.
2. RDMAP does not provide ordering between operations that are
generated from the two ends of an RDMAP Stream.
3. RDMA Messages that use Tagged and Untagged Buffers MAY be
Placed in any order. If an application uses overlapping
buffers (points different Messages or portions of a single
Message at the same buffer), then it is possible that the last
incoming write to the Data Sink buffer will not be the last
outgoing data sent from the Data Source.
4. For a Send operation, the contents of an Untagged Buffer at
the Data Sink MAY be indeterminate until the Send is Delivered
to the ULP at the Data Sink.
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5. For an RDMA Write operation, the contents of the Tagged Buffer
at the Data Sink MAY be indeterminate until a subsequent Send
is Delivered to the ULP at the Data Sink.
6. For an RDMA Read operation, the contents of the Tagged Buffer
at the Data Sink MAY be indeterminate until the RDMA Read
Response Message has been Delivered at the Local Peer.
Statements 4, 5, and 6 imply "no peeking" at the data to see
if it is done. It is possible for some data to arrive before
logically earlier data does, and peeking may cause
unpredictable application failure
7. If the ULP or Application modifies the contents of Tagged or
Untagged Buffers being modified by an RDMA Operation while the
RDMAP is processing the RDMA Operation, the state of the
Buffers is indeterminate.
8. If the ULP or Application modifies the contents of Tagged or
Untagged Buffers read by an RDMA Operation while the RDMAP is
processing the RDMA Operation, the results of the read are
indeterminate.
9. The Completion of an RDMA Write or Send Operation at the Local
Peer does not guarantee that the ULP Message has yet reached
the Remote Peer ULP Buffer or been examined by the Remote ULP.
10. Send Messages MUST be Delivered to the ULP at the Remote Peer
after they are Delivered to RDMAP by DDP and in the order that
the they were Delivered to RDMAP.
Note that DDP ordering rules ensure that this will be the same
order that they were submitted at the Local Peer and that any
prior RDMA Writes have been submitted for ordered Placement at
the Remote Peer. This means that when the ULP sees the
Delivery of the Send, the memory buffers targeted by any
preceding RDMA Writes and Sends are available to be accessed
locally or remotely as authorized. If the ULP overlaps its
buffers for different operations, the data from the RDMA Write
or Send may be overwritten by subsequent RDMA Operations
before the ULP receives and processes the Delivery.
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11. RDMA Read Response Messages MUST be Delivered to the ULP at
the Remote Peer after they are Delivered to RDMAP by DDP and
in the order that the they were Delivered to RDMAP.
DDP ordering rules ensure that this will be the same order
that they were submitted at the Local Peer. This means that
when the ULP sees the Delivery of the RDMA Read Response, the
memory buffers targeted by the RDMA Read Response are
available to be accessed locally or remotely as authorized. If
the ULP overlaps its buffers for different operations, the
data from the RDMA Read Response may be overwritten by
subsequent RDMA Operations before the ULP receives and
processes the Delivery.
12. RDMA Read Request Messages, including zero-length RDMA Read
Requests, MUST NOT start processing at the Remote Peer until
they have been Delivered to RDMAP by DDP.
Note: the ULP is assured that data written can be read back.
For example, if an RDMA Read Request is issued by the local
peer, targeting the same ULP Buffer as a preceding Send or
RDMA Write (in the same direction as the RDMA Read Request),
and there are no other sources of update for the ULP Buffer,
then the remote peer will send back the data written by the
Send or RDMA Write. That is, for this example the ULP Buffer:
is Advertised for use on a series of RDMA Messages, is only
valid on the RDMAP Stream for which it is advertised, and is
not locally updated while the series of RDMAP Messages are
performed. For this example, order rule (12) assures that
subsequent local or remote accesses to the ULP Buffer contain
the data written by the Send or RDMA Write.
RDMA Read Response Messages MAY be generated at the Remote
Peer after subsequent RDMA Write Messages or Send Messages
have been Placed or Delivered. Therefore, when an application
does an RDMA Read Request followed by an RDMA Write (or Send)
to the same buffer, it may get the data from the later RDMA
Write (or Send) in the RDMA Read Response Message, even though
the operations completed in order at the Local Peer. If this
behavior is not desired, the Local Peer ULP must Fence the
later RDMA write (or Send) by withholding the RDMA Write
Message until all outstanding RDMA Read Responses have been
Delivered.
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13. The RDMAP Layer MUST submit RDMA Messages to the DDP layer in
the order the RDMA Operations are submitted to the RDMAP Layer
by the ULP.
14. A Send or RDMA Write Message MUST NOT be considered Complete
at the Local Peer (Data Source) until it has been successfully
completed at the DDP layer.
15. RDMA Operations MUST be Completed at the Local Peer in the
order that they were submitted by the ULP.
16. At the Data Sink, an incoming Send Message MUST be Delivered
to the ULP only after the DDP Message has been Delivered to
the RDMAP Layer by the DDP layer.
17. RDMA Read Response Message processing at the Remote Peer
(reading the specified Tagged Buffer) MUST be started only
after the RDMA Read Request Message has been Delivered by the
DDP layer (thus all previous RDMA Messages have been properly
submitted for ordered Placement).
18. Send Messages MAY be Completed at the Remote Peer (Data Sink)
before prior incoming RDMA Read Request Messages have
completed their response processing.
19. An RDMA Read operation MUST NOT be Completed at the Local Peer
until the DDP layer Delivers the associated incoming RDMA Read
Response Message.
20. If more than one outstanding RDMA Read Request Messages are
supported by both peers, the RDMA Read Response Messages MUST
be submitted to the DDP layer on the Remote Peer in the order
the RDMA Read Request Messages were Delivered by DDP, but the
actual read of the buffer contents MAY take place in any order
at the Remote Peer.
This simplifies Local Peer Completion processing for RDMA
Reads in that a Delivered RDMA Read Response MUST be
sufficient to Complete the RDMA Read Operation.
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6 RDMAP Stream Management
RDMAP Stream management consists of RDMAP Stream Initialization
and RDMAP Stream Termination.
6.1 Stream Initialization
RDMAP Stream initialization occurs after the LLP Stream has been
created (e.g., for DDP/MPA over TCP the first TCP Segment after
the SYN, SYN/ACK exchange). The ULP is responsible for
transitioning the LLP Stream into RDMA enabled mode. The switch to
RDMA mode typically occurs sometime after LLP Stream setup. Once
in RDMA enabled mode, an implementation MUST send only RDMA
Messages across the transport Stream until the RDMAP Stream is
torn down.
For each direction of an RDMAP Stream:
* For a given RDMAP Stream, the number of outstanding RDMA Read
Requests is limited per RDMAP Stream direction.
* It is the ULP's responsibility to set the maximum number of
outstanding, inbound RDMA Read Requests per RDMAP Stream
direction.
* The RDMAP Layer MUST provide the maximum number of outstanding,
inbound RDMA Read Requests per RDMAP Stream direction that were
negotiated between the ULP and the Local Peer's RDMAP Layer.
The negotiation mechanism is outside the scope of this
specification.
* It is the ULP's responsibility to set the maximum number of
outstanding, outbound RDMA Read Requests per RDMAP Stream
direction.
* The RDMAP Layer MUST provide the maximum number of outstanding,
outbound RDMA Read Requests for the RDMAP Stream direction that
were negotiated between the ULP and the Local Peer's RDMAP
Layer. The negotiation mechanism is outside the scope of this
specification.
* The Local Peer's ULP is responsible for negotiating with the
Remote Peer's ULP the maximum number of outstanding RDMA Read
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Requests for the RDMAP Stream direction. It is recommended that
the ULP set the maximum number of outstanding, inbound RDMA
Read Requests equal to the maximum number of outstanding,
outbound RDMA Read Requests for a given RDMAP Stream direction.
* For outbound RDMA Read Requests, the RDMAP Layer MUST NOT
exceed the maximum number of outstanding, outbound RDMA Read
Requests that were negotiated between the ULP and the Local
Peer's RDMAP Layer.
* For inbound RDMA Read Requests, the RDMAP Layer MUST NOT exceed
the maximum number of outstanding, inbound RDMA Read Requests
that were negotiated between the ULP and the Local Peer's RDMAP
Layer.
6.2 Stream Teardown
There are three methods for terminating an RDMAP Stream: ULP
Graceful Termination, RDMAP Abortive Termination, and LLP Abortive
Termination.
The ULP is responsible for performing ULP Graceful Termination.
After a ULP Graceful Termination, either side of the Stream can
initiate LLP Graceful Termination, using the graceful termination
mechanism provided by the LLP.
RDMAP Abortive Termination allows the RDMAP to issue a Terminate
Message describing the reason the RDMAP Stream was terminated. The
next section (6.2.1 RDMAP Abortive Termination) describes the
RDMAP Abortive Termination in detail.
LLP Abortive Termination results due to a LLP error and causes the
RDMAP Stream to be torn down midstream, without an RDMAP Terminate
Message. While this last method is highly undesirable, it is
possible and the ULP should take this into consideration.
6.2.1 RDMAP Abortive Termination
RDMAP defines a Terminate operation that SHOULD be invoked when
either an RDMAP error is encountered or a LLP error is surfaced to
the RDMAP layer by the LLP.
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It is not always possible to send the Terminate Message. For
example, certain LLP errors may occur that cause the LLP Stream to
be torn down before a) RDMAP is aware of the error, b) before
RDMAP is able to send the Terminate Message, or c) after RDMAP has
posted the Terminate Message to the LLP, but it has not yet been
transmitted by the LLP.
Note that an RDMAP Abortive Termination may entail loss of data.
In general, when a Terminate Message is received it is impossible
to tell for sure what unacknowledged RDMA Messages were Completed
successfully at the Remote Peer. Thus the state of all outstanding
RDMA Messages is indeterminate and the Messages SHOULD be
considered Completed in error.
When a peer sends or receives a Terminate Message, it MAY
immediately teardown the LLP Stream. The peer SHOULD perform a
graceful LLP teardown to ensure the Terminate Message is
successfully Delivered.
See section 4.8 Terminate Header for a description of the
Terminate Message and its contents. See section 5.4 Terminate
Message for a description of the Terminate Message semantics.
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7 RDMAP Error Management
The RDMAP protocol does not have RDMAP or DDP layer error recovery
operations built in. If everything is working, the LLP guarantees
will ensure that the Messages are arriving at the destination.
If errors are detected at the RDMAP or DDP layer, then the RDMAP,
DDP and LLP Streams are Abortively Terminated (see section 4.8
Terminate Header on page 34).
In general poor implementations or improper ULP programming causes
the errors detected at the RDMAP and DDP layers. In these cases,
returning a diagnostic termination error Message and closing the
RDMAP Stream is far simpler than attempting to maintain the RDMAP
Stream, particularly when the cause of the error is not known.
If an LLP does not support teardown of a Stream independent of
other Streams and an RDMAP error results in the Termination of a
specific Stream, then the LLP MUST label the Stream as an
erroneous Stream and MUST NOT allow any further data transfer on
that Stream after RDMAP requests the Stream to be torn down.
For a specific LLP connection, when all Streams are either
gracefully torn down or are labeled as erroneous Streams, the LLP
connection MUST be torn down.
Since errors are detected at the Remote Peer (possibly long) after
RDMA Messages are passed to DDP and the LLP at the Local Peer and
Completed, the sender cannot easily determine which of its
Messages have been received. (RDMA Reads are an exception to this
rule).
For a list of errors returned to the Remote Peer as a result of an
Abortive Termination, see section 4.8 Terminate Header on page 34.
7.1 RDMAP Error Surfacing
If an error occurs at the Local Peer, the RDMAP layer MUST attempt
to inform the local ULP that the error has occurred.
The Local Peer MUST send a Terminate Message for each of the
following cases:
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1. For errors detected while creating RDMA Write, Send, Send with
Invalidate, Send with Solicited Event, Send with Solicited
Event and Invalidate, or RDMA Read Requests, or other reasons
not directly associated with an incoming Message, the
Terminate Message and Error code are sent instead of the
request. In this case, the Error Type and Error Code fields
are included in the Terminate Message, but the Terminated DDP
Header and Terminated RDMA Header fields are set to zero.
2. For errors detected on an incoming RDMA Write, Send, Send with
Invalidate, Send with Solicited Event, Send with Solicited
Event and Invalidate, or Read Response Message (after the
Message has been Delivered by DDP), the Terminate Message is
sent at the earliest possible opportunity, preferably in the
next outgoing RDMA Message. In this case, the Error Type,
Error Code, ULP PDU Length, and Terminated DDP Header fields
are included in the Terminate Message, but the Terminated RDMA
Header field is set to zero.
3. For errors detected on an incoming RDMA Read Request Message
(after the Message has been Delivered by DDP), the Terminate
Message is sent at the earliest possible opportunity,
preferably in the next outgoing RDMA Message. In this case,
the Error Type, Error Code, ULP PDU Length, Terminated DDP
Header, and Terminated RDMA Header fields are included in the
Terminate Message.
4. If more than one error is detected on incoming RDMA Messages,
before the Terminate Message can be sent, then the first RDMA
Message (and its associated DDP Segment) that experienced an
error MUST be captured by the Terminate Message in accordance
with rules 2 and 3 above.
7.2 Errors Detected at the Remote Peer on Incoming RDMA Messages
On incoming RDMA Writes, RDMA Read Response, Sends, Send with
Invalidate, Send with Solicited Event, Send with Solicited Event
and Invalidate, and Terminate Messages, the following must be
validated:
1. The DDP Layer MUST validate all DDP Segment fields.
2. The RDMA OpCode MUST be valid.
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3. The RDMA Version MUST be valid.
Additionally, on incoming Send with Invalidate and Send with
Solicited Event and Invalidate Messages, the following must
also be validated:
4. The Invalidate STag MUST be valid.
5. The STag MUST be associated to this RDMAP Stream.
On incoming RDMA Request Messages, the following must be
validated:
1. The DDP Layer MUST validate all Untagged DDP Segment fields.
2. The RDMA OpCode MUST be valid.
3. The RDMA Version MUST be valid.
4. For non-zero length RDMA Read Request Messages:
a. The Data Source STag MUST be valid.
b. The Data Source STag MUST be associated to this RDMAP
Stream.
c. The Data Source Tagged Offset MUST fall in the range of
legal offsets associated with the Data Source STag.
d. The sum of the Data Source Tagged Offset and the RDMA Read
Message Size MUST fall in the range of legal offsets
associated with the Data Source STag.
e. The sum of the Data Source Tagged Offset and the RDMA Read
Message Size MUST NOT cause the Data Source Tagged Offset
to wrap.
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8 Security Considerations
This section references the resources that discuss protocol-
specific security considerations and implications of using RDMAP
with existing security services. A detailed analysis of the
security issues around implementation and use of the RDMAP can be
found in [RDMASEC].
[RDMASEC] introduces the RDMA reference model and discusses how
the resources of this model are vulnerable to attacks and the
types of attack these vulnerabilities are subject to. It also
details the levels of Trust available in this peer-to-peer model
and how this defines the nature of resource sharing.
The IPsec requirements for RDDP are based on the version of IPsec
specified in RFC 2401 [RFC 2401] and related RFCs, as profiled by
RFC 3723 [RFC 3723], despite the existence of a newer version of
IPsec specified in RFC 4301 [RFC 4301] and related RFCs. One of
the important early applications of the RDDP protocols is their
use with iSCSI [iSER]; RDDP's IPsec requirements follow those of
IPsec in order to facilitate that usage by allowing a common
profile of IPsec to be used with iSCSI and the RDDP protocols. In
the future, RFC 3723 may be updated to the newer version of IPsec,
the IPsec security requirements of any such update should apply
uniformly to iSCSI and the RDDP protocols.
8.1 Summary of RDMAP specific Security Requirements
[RDMASEC] defines the security requirements for the implementation
of the components of the RDMA reference model, namely the RDMA
enabled NIC (RNIC) and the Privileged Resource Manager. An RDMAP
implementation conforming to this specification MUST conform to
these requirements.
8.1.1 RDMAP (RNIC) Requirements
RDMAP provides several countermeasures for all types of attacks as
introduced in [RDMASEC]. In the following, this specification
lists all security requirements which MUST be implemented by the
RNIC. A more detailed discussion of RNIC security requirements can
be found in Section 5 of [RDMASEC].
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1. An RNIC MUST ensure that a specific Stream in a specific
Protection Domain cannot access an STag in a different
Protection Domain.
2. An RNIC MUST ensure that if an STag is limited in scope to a
single Stream, no other Stream can use the STag.
3. An RNIC MUST ensure that a Remote Peer is not able to access
memory outside of the buffer specified when the STag was
enabled for remote access.
4. An RNIC MUST provide a mechanism for the ULP to establish and
revoke the association of a ULP Buffer to an STag and TO
range.
5. An RNIC MUST provide a mechanism for the ULP to establish and
revoke read, write, or read and write access to the ULP Buffer
referenced by an STag.
6. An RNIC MUST ensure that the network interface can no longer
modify an advertised buffer after the ULP revokes remote
access rights for an STag.
7. An RNIC MUST ensure that a Remote Peer is not able to
invalidate an STag enabled for remote access, if the STag is
shared on multiple streams.
8. An RNIC MUST choose the value of STags in a way difficult to
predict. It is RECOMMENDED to sparsely populate them over the
full available range.
9. An RNIC MUST NOT enable sharing a CQ across ULPs that do not
share partial mutual trust.
10. An RNIC MUST ensure that if a CQ overflows, any Streams which
do not use the CQ MUST remain unaffected.
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11. An RNIC implementation SHOULD provide a mechanism to cap the
number of outstanding RDMA Read Requests.
12. An RNIC MUST NOT enable firmware to be loaded on the RNIC
directly from an untrusted Local Peer or Remote Peer, unless
the Peer is properly authenticated (by a mechanism outside the
scope of this specification. The mechanism presumably entails
authenticating that the remote ULP has the right to perform
the update), and the update is done via a secure protocol,
such as IPsec.
8.1.2 Privileged Resource Manager Requirements
With RDMAP, all reservations of local resources are initiated from
local ULPs. To protect from local attacks including unfair
resource distribution and gaining unauthorized access to RNIC
resources, a Privileged Resource Manager (PRM) must be
implemented, which manages all local resource allocation. Note
that the PRM must not be provided as an independent component, its
functionality can also be implemented as part of the privileged
ULP or as part of the RNIC itself.
An PRM implementation must meet the following security
requirements (a more detailed discussion of PRM security
requirements can be found in Section 5 of [RDMASEC]):
1. All Non-Privileged ULP interactions with the RNIC Engine that
could affect other ULPs MUST be done using the Resource
Manager as a proxy.
2. All ULP resource allocation requests for scarce resources MUST
also be done using a Privileged Resource Manager.
3. The Privileged Resource Manager MUST NOT assume different ULPs
share Partial Mutual Trust unless there is a mechanism to
ensure that the ULPs do indeed share partial mutual trust.
4. If Non-Privileged ULPs are supported, the Privileged Resource
Manager MUST verify that the Non-Privileged ULP has the right
to access a specific Data Buffer before allowing an STag for
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which the ULP has access rights to be associated with a
specific Data Buffer.
5. The Privileged Resource Manager MUST control the allocation of
CQ entries.
6. The Privileged Resource Manager SHOULD prevent a Local Peer
from allocating more than its fair share of resources.
7. RDMA Read Request Queue resource consumption MUST be
controlled by the Privileged Resource Manager such that
RDMAP/DDP Streams which do not share Partial Mutual Trust do
not share RDMA Read Request Queue resources.
8. If an RNIC provides the ability to share receive buffers
across multiple Streams, the combination of the RNIC and the
Privileged Resource Manager MUST be able to detect if the
Remote Peer is attempting to consume more than its fair share
of resources so that the Local Peer can apply countermeasures
to detect and prevent the attack.
8.2 Security Services for RDMAP
RDMAP is using IP based network services to control, read and
write data buffers over the network. Therefore, all exchanged
control and data packets are vulnerable to spoofing, tampering
and information disclosure attacks.
RDMAP Streams that are subject to impersonation attacks, or
Stream hijacking attacks, can be authenticated, have their
integrity protected, and be protected from replay attacks.
Furthermore, confidentiality protection can be used to protect
from eavesdropping.
8.2.1 Available Security Services
The IPsec protocol suite [RFC2401] defines strong countermeasures
to protect an IP stream from those attacks. Several levels of
protection can guarantee session confidentiality, per-packet
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source authentication, per-packet integrity and correct packet
sequencing.
RDMAP security may also profit from SSL or TLS security services
provided for TCP based ULPs [RFC4346]. Used underneath RDMAP,
these security services also provides for stream authentication,
data integrity and confidentiality. As discussed in [RDMASEC],
limitations on the maximum packet length to be carried over the
network and potentially inefficient out-of-order packet processing
at the data sink makes SSL and TLS less appropriate for RDMAP than
IPsec.
If SSL is layered on top of RDMAP, SSL does not protect the RDMAP
headers. Thus, a man-in-the-middle attack can still occur by
modifying the RDMAP header to incorrectly place the data into the
wrong buffer, thus effectively corrupting the data stream.
By remaining independent of ULP and LLP security protocols, RDMAP
will benefit from continuing improvements at those layers. Users
are provided flexibility to adapt to their specific security
requirements and the ability to adapt to future security
challenges. Given this, the vulnerabilities of RDMAP to active
third-party interference are no greater than any other protocol
running over an LLP such as TCP or SCTP.
8.2.2 Requirements for IPsec Services for RDMAP
Because IPsec is designed to secure arbitrary IP packet streams,
including streams where packets are lost, RDMAP can run on top of
IPsec without any change. IPsec packets are processed (e.g.,
integrity checked and possibly decrypted) in the order they are
received, and an RDMAP Data Sink will process the decrypted RDMA
Messages contained in these packets in the same manner as RDMA
Messages contained in unsecured IP packets.
The IP Storage working group has defined the normative IPsec
requirements for IP Storage [RFC3723]. Portions of this
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specification are applicable to the RDMAP. In particular, a
compliant implementation of IPsec services for RDMAP MUST meet
the requirements as outlined in Section 2.3 of [RFC3723]. Without
replicating the detailed discussion in [RFC3723], this includes
the following requirements:
1. The implementation MUST support IPsec ESP [RFC2406], as well
as the replay protection mechanisms of IPsec. When ESP is
utilized, per-packet data origin authentication, integrity and
replay protection MUST be used.
2. It MUST support ESP in tunnel mode and MAY implement ESP in
transport mode.
3. It MUST support IKE [RFC2409] for peer authentication,
negotiation of security associations, and key management,
using the IPsec DOI [RFC2407].
4. It MUST NOT interpret the receipt of a IKE Phase 2 delete
message as a reason for tearing down the RDMAP stream. Since
IPsec acceleration hardware may only be able to handle a
limited number of active IKE Phase 2 SAs, idle SAs may be
dynamically brought down and a new SA be brought up again, if
activity resumes.
5. It MUST support peer authentication using a pre-shared key,
and MAY support certificate-based peer authentication using
digital signatures. Peer authentication using the public key
encryption methods [RFC2409] SHOULD NOT be used.
6. It MUST support IKE Main Mode and SHOULD support Aggressive
Mode. IKE Main Mode with pre-shared key authentication SHOULD
NOT be used when either of the peers uses a dynamically
assigned IP address.
7. When digital signatures are used to achieve authentication,
either IKE Main Mode or IKE Aggressive Mode MAY be used. In
these cases, an IKE negotiator SHOULD use IKE Certificate
Request Payload(s) to specify the certificate authority (or
authorities) that are trusted in accordance with its local
policy. IKE negotiators SHOULD check the pertinent Certificate
Revocation List (CRL) before accepting a PKI certificate for
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use in IKE's authentication procedures.
8. Access to locally stored secret information (pre-shared or
private key for digital signing) must be suitably restricted,
since compromise of the secret information nullifies the
security properties of the IKE/IPsec protocols.
9. It MUST follow the guidelines of Section 2.3.4 of [RFC3723] on
the setting of IKE parameters to achieve a high level of
interoperability without requiring extensive configuration.
Furthermore, implementation and deployment of the IPsec services
for RDDP should follow the Security Considerations outlined in
Section 5 of [RFC3723].
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9 IANA
IANA Considerations
This document requests no direct action from IANA. The following
consideration is listed here as commentary.
If RDMAP was enabled a priori for a ULP by connecting to a well-
known port, this well-known port would be registered for the RDMAP
with IANA. The registration of the well-known port will be the
responsibility of the ULP specification.
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10 References
10.1 Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2406] Kent, S. and R. Atkinson, "IP Encapsulating Security
Payload (ESP)", RFC 2406, November 1998.
[RFC2407] Piper, D., "The Internet IP Security Domain of
Interpretation of ISAKMP", RFC 2407, November 1998.
[RFC2409] Harkins, D. and D. Carrel, "The Internet Key Exchange
(IKE)", RFC 2409, November 1998.
[RFC3723] Aboba B. et al., "Secure Block Storage Protocols over
IP", RFC 3723, April 2004.
[RFC 4301] S. Kent and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, December 2005.
[VERBS] J. Hilland, "RDMA Protocol Verbs Specification", draft-
hilland-iwarp-verbs-v1.0 RDMA Consortium, April 2003.
[DDP] H. Shah et al., "Direct Data Placement over Reliable
Transports", draft-ietf-rddp-ddp-07.txt, September 2006.
[MPA] P. Culley et al., "Marker PDU Aligned Framing for TCP
Specification", draft-ietf-rddp-mpa-06.txt, September 2006.
[SCTP] R. Stewart et al., "Stream Control Transmission Protocol",
RFC 2960, October 2000.
[TCP] Postel, J., "Transmission Control Protocol", STD 7, RFC 793,
September 1981.
[RDMASEC] J. Pinkerton et al., "DDP/RDMAP Security", draft-ietf-
rddp-security-09.txt, March 2005.
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[iSER] M. Ko, et. al., "iSCSI Extensions for RDMA Specification,
"Internet-Draft, draft-ietf-ips-iser-05.txt, Work in Progress,
October 2005.
10.2 Informative References
[RFC2401] Atkinson, R., Kent, S., "Security Architecture for the
Internet Protocol", RFC 2401, November 1998.
[RFC4346] Dierks, T. and C. Allen, "The TLS Protocol Version 1.1",
RFC 4346, April 2006.
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11 Appendix
11.1 DDP Segment Formats for RDMA Messages
This appendix is for information only and is NOT part of the
standard. It simply depicts the DDP Segment format for the various
RDMA Messages.
11.1.1 DDP Segment for RDMA Write
The following figure depicts an RDMA Write, DDP Segment:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DDP Control | RDMA Control |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Sink STag |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Sink Tagged Offset |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RDMA Write ULP Payload |
// //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11 RDMA Write, DDP Segment format
11.1.2 DDP Segment for RDMA Read Request
The following figure depicts an RDMA Read Request, DDP Segment:
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DDP Control | RDMA Control |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved (Not Used) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DDP (RDMA Read Request) Queue Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DDP (RDMA Read Request) Message Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DDP (RDMA Read Request) Message Offset |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Sink STag (SinkSTag) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Data Sink Tagged Offset (SinkTO) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RDMA Read Message Size (RDMARDSZ) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Source STag (SrcSTag) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Data Source Tagged Offset (SrcTO) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12 RDMA Read Request, DDP Segment format
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11.1.3 DDP Segment for RDMA Read Response
The following figure depicts an RDMA Read Response, DDP Segment:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DDP Control | RDMA Control |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Sink STag |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Sink Tagged Offset |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RDMA Read Response ULP Payload |
// //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 13 RDMA Read Response, DDP Segment format
11.1.4 DDP Segment for Send and Send with Solicited Event
The following figure depicts a Send and Send with Solicited
Request, DDP Segment:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DDP Control | RDMA Control |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved (Not Used) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (Send) Queue Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (Send) Message Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (Send) Message Offset |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Send ULP Payload |
// //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Figure 14 Send and Send with Solicited Event, DDP Segment format
11.1.5 DDP Segment for Send with Invalidate and Send with SE and
Invalidate
The following figure depicts a Send with invalidate and Send with
Solicited and Invalidate Request, DDP Segment:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DDP Control | RDMA Control |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Invalidate STag |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (Send) Queue Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (Send) Message Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (Send) Message Offset |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Send ULP Payload |
// //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 15 Send with Invalidate and Send with SE and Invalidate,
DDP Segment
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11.1.6 DDP Segment for Terminate
The following figure depicts a Terminate, DDP Segment:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DDP Control | RDMA Control |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved (Not Used) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DDP (Terminate) Queue Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DDP (Terminate) Message Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DDP (Terminate) Message Offset |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Terminate Control | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DDP Segment Length (if any) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
+ +
| Terminated DDP Header (if any) |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// //
| Terminated RDMA Header (if any) |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 16 Terminate, DDP Segment format
11.2 Ordering and Completion Table
The following table summarizes the ordering relationships that are
defined in section 5.5 Ordering and Completions from the
standpoint of the local peer issuing the two Operations. Note, in
the table that follows Send includes Send, Send with Invalidate,
Send with Solicited Event, and Send with Solicited Event and
Invalidate
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------+-------+----------------+----------------+----------------
First | Later | Placement | Placement | Ordering
Op | Op | guarantee at | guarantee | guarantee at
| | Remote Peer | Local Peer | Remote Peer
| | | |
------+-------+----------------+----------------+----------------
Send | Send | No placement | Not applicable | Completed in
| | guarantee. If | | order.
| | guarantee is | |
| | necessary, see | |
| | footnote 1. | |
------+-------+----------------+----------------+----------------
Send | RDMA | No placement | Not applicable | Not applicable
| Write | guarantee. If | |
| | guarantee is | |
| | necessary, see | |
| | footnote 1. | |
------+-------+----------------+----------------+----------------
Send | RDMA | No placement | RDMA Read | RDMA Read
| Read | guarantee | Response | Response
| | between Send | Payload will | Message will
| | Payload and | not be placed | not be
| | RDMA Read | at the local | generated until
| | Request Header | peer until the | Send has been
| | | Send Payload is| Completed
| | | placed at the |
| | | remote peer |
------+-------+----------------+----------------+----------------
RDMA | Send | No placement | Not applicable | Not applicable
Write | | guarantee. If | |
| | guarantee is | |
| | necessary, see | |
| | footnote 1. | |
------+-------+----------------+----------------+----------------
RDMA | RDMA | No placement | Not applicable | Not applicable
Write | Write | guarantee. If | |
| | guarantee is | |
| | necessary, see | |
| | footnote 1. | |
------+-------+----------------+----------------+----------------
RDMA | RDMA | No placement | RDMA Read | Not applicable
Write | Read | guarantee | Response |
| | between RDMA | Payload will |
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| | Write Payload | not be placed |
| | and RDMA Read | at the local |
| | Request Header | peer until the |
| | | RDMA Write |
| | | Payload is |
| | | placed at the |
| | | remote peer |
------+-------+----------------+----------------+----------------
RDMA | Send | No placement | Send Payload | Not applicable
Read | | guarantee | may be placed |
| | between RDMA | at the remote |
| | Read Request | peer before the|
| | Header and Send| RDMA Read |
| | payload | Response is |
| | | generated. |
| | | If guarantee is|
| | | necessary, see |
| | | footnote 2. |
------+-------+----------------+----------------+----------------
RDMA | RDMA | No placement | RDMA Write | Not applicable
Read | Write | guarantee | Payload may be |
| | between RDMA | placed at the |
| | Read Request | remote peer |
| | Header and RDMA| before the RDMA|
| | Write payload | Read Response |
| | | is generated. |
| | | If guarantee is|
| | | necessary, see |
| | | footnote 2. |
------+-------+----------------+----------------+----------------
RDMA | RDMA | No placement | No placement | Second RDMA
Read | Read | guarantee of | guarantee of | Read Response
| | the two RDMA | the two RDMA | will not be
| | Read Request | Read Response | generated until
| | Headers | Payloads. | first RDMA Read
| | Additionally, | | Response is
| | there is no | | generated.
| | guarantee that | |
| | the Tagged | |
| | Buffers | |
| | referenced in | |
| | the RDMA Read | |
| | will be read in| |
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| | order | |
Figure 17 Operation Ordering
Footnote 1: If the guarantee is necessary, a ULP may insert an
RDMA Read Operation and wait for it to complete to act as a Fence.
Footnote 2: If the guarantee is necessary, a ULP may wait for the
RDMA Read Operation to complete before performing the Send.
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12 Author's Address
Paul R. Culley
Hewlett-Packard Company
20555 SH 249
Houston, Tx. USA 77070-2698
Phone: 281-514-5543
Email: paul.culley@hp.com
Dave Garcia
Hewlett-Packard Company
19333 Vallco Parkway
Cupertino, Ca. USA 95014
Phone: 408.285.6116
Email: dave.garcia@hp.com
Jeff Hilland
Hewlett-Packard Company
20555 SH 249
Houston, Tx. USA 77070-2698
Phone: 281-514-9489
Email: jeff.hilland@hp.com
Bernard Metzler
IBM Research GmbH
Zurich Research Laboratory
Saeumerstrasse 4
CH-8803 Rueschlikon, Switzerland
Phone: +41 44 724 8605
Email: bmt@zurich.ibm.com
Renato J. Recio
IBM Corp.
11501 Burnett Road
Austin, Tx. USA 78758
Phone: 512-838-3685
Email: recio@us.ibm.com
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13 Contributors
Dwight Barron
Hewlett-Packard Company
20555 SH 249
Houston, Tx. USA 77070-2698
Phone: 281-514-2769
Email: dwight.barron@hp.com
Caitlin Bestler
Broadcom Corporation
16215 Alton Parkway
Irvine, CA. USA 92619-7013
Phone: 949-926-6383
Email: caitlinb@broadcom.com
John Carrier
Cray, Inc.
411 First Avenue S, Suite 600
Seattle, WA 98104-2860 USA
Phone: 206-701-2090
Email: carrier@cray.com
Ted Compton
EMC Corporation
Research Triangle Park, NC 27709, USA
Phone: 919-248-6075
Email: compton_ted@emc.com
Uri Elzur
Broadcom Corporation
16215 Alton Parkway
Irvine, California 92619-7013 USA
Phone: +1 (949) 585-6432
Email: Uri@Broadcom.com
Hari Ghadia
Adaptec, Inc.
691 S. Milpitas Blvd.,
Milpitas, CA 95035 USA
Phone: +1 (408) 957-5608
Email: hari_ghadia@adaptec.com
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Howard C. Herbert
Intel Corporation
MS CH7-404
5000 West Chandler Blvd.
Chandler, Arizona 85226
Phone: 480-554-3116
Email: howard.c.herbert@intel.com
Mike Ko
IBM
650 Harry Rd.
San Jose, CA 95120
Phone: (408) 927-2085
Email: mako@us.ibm.com
Mike Krause
Hewlett-Packard Company
43LN
19410 Homestead Road
Cupertino, CA 95014 USA
Phone: 408-447-3191
Email: krause@cup.hp.com
Dave Minturn
Intel Corporation
MS JF1-210
5200 North East Elam Young Parkway
Hillsboro, Oregon 97124
Phone: 503-712-4106
Email: dave.b.minturn@intel.com
Mike Penna
Broadcom Corporation
16215 Alton Parkway
Irvine, California 92619-7013 USA
Phone: +1 (949) 926-7149
Email: MPenna@Broadcom.com
Jim Pinkerton
Microsoft, Inc.
One Microsoft Way
Redmond, WA, USA 98052
Email: jpink@microsoft.com
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Hemal Shah
Broadcom Corporation
16215 Alton Parkway
Irvine, CA. USA 92619-7013
Phone: 949-926-6941
Email:
Allyn Romanow
Cisco Systems
170 W Tasman Drive
San Jose, CA 95134 USA
Phone: +1 408 525 8836
Email: allyn@cisco.com
Tom Talpey
Network Appliance
1601 Trapelo Road #16
Waltham, MA 02451 USA
Phone: +1 (781) 768-5329
EMail: thomas.talpey@netapp.com
Patricia Thaler
Broadcom Corporation
16215 Alton Parkway
Irvine, CA. USA 92619-7013
Phone: +1-916-570-2707
email: pthaler@broadcom.com
Jim Wendt
Hewlett-Packard Company
8000 Foothills Boulevard MS 5668
Roseville, CA 95747-5668 USA
Phone: +1 916 785 5198
Email: jim_wendt@hp.com
Madeline Vega
IBM
11400 Burnet Rd. Bld.45-2L-007
Austin, TX. USA 78758
Phone: 512-838-7739
Email: mvega1@us.ibm.com
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Claudia Salzberg
IBM
11501 Burnet Rd. Bld.902-5B-014
Austin, TX. USA 78758
Phone: 512-838-5156
Email: salzberg@us.ibm.com
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14 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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15 Full Copyright Statement
Copyright (C) The Internet Society (2006).
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 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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