draft-ietf-nfsv4-nfsdirect-08.txt		rfc5667.txt
	NFSv4 Working Group Tom Talpey		Internet Engineering Task Force (IETF) T. Talpey
	Internet-Draft NetApp		Request for Comments: 5667 Unaffiliated
	Intended status: Standards Track Brent Callaghan		Category: Standards Track B. Callaghan
	Expires: October 17, 2008 Apple		ISSN: 2070-1721 Apple
	April 16, 2008		January 2010
	NFS Direct Data Placement		Network File System (NFS) Direct Data Placement
	draft-ietf-nfsv4-nfsdirect-08
	Status of this Memo		Abstract
	By submitting this Internet-Draft, each author represents that any		This document defines the bindings of the various Network File System
	applicable patent or other IPR claims of which he or she is aware		(NFS) versions to the Remote Direct Memory Access (RDMA) operations
	have been or will be disclosed, and any of which he or she becomes		supported by the RPC/RDMA transport protocol. It describes the use
	aware will be disclosed, in accordance with Section 6 of BCP 79.		of direct data placement by means of server-initiated RDMA operations
			into client-supplied buffers for implementations of NFS versions 2,
			3, 4, and 4.1 over such an RDMA transport.
	Internet-Drafts are working documents of the Internet Engineering		Status of This Memo
	Task Force (IETF), its areas, and its working groups. Note that
	other groups may also distribute working documents as Internet-
	Drafts.
	Internet-Drafts are draft documents valid for a maximum of six		This is an Internet Standards Track document.
	months and may be updated, replaced, or obsoleted by other
	documents at any time. It is inappropriate to use Internet-Drafts
	as reference material or to cite them other than as "work in
	progress."
	The list of current Internet-Drafts can be accessed at		This document is a product of the Internet Engineering Task Force
	http://www.ietf.org/ietf/1id-abstracts.txt		(IETF). It represents the consensus of the IETF community. It has
			received public review and has been approved for publication by the
			Internet Engineering Steering Group (IESG). Further information on
			Internet Standards is available in Section 2 of RFC 5741.
	The list of Internet-Draft Shadow Directories can be accessed at		Information about the current status of this document, any errata,
	http://www.ietf.org/shadow.html.		and how to provide feedback on it may be obtained at
			http://www.rfc-editor.org/info/rfc5667.
	Abstract		Copyright Notice
	This draft defines the bindings of the various Network File System		Copyright (c) 2010 IETF Trust and the persons identified as the
	(NFS) versions to the Remote Direct Memory Access (RDMA) operations		document authors. All rights reserved.
	supported by the RPC/RDMA transport protocol. It describes the use
	of direct data placement by means of server-initiated RDMA operations
	into client-supplied buffers for implementations of NFS versions 2,
	3, 4 and 4.1 over such an RDMA transport.
	Table of Contents		This document is subject to BCP 78 and the IETF Trust's Legal
			Provisions Relating to IETF Documents
			(http://trustee.ietf.org/license-info) in effect on the date of
			publication of this document. Please review these documents
			carefully, as they describe your rights and restrictions with respect
			to this document. Code Components extracted from this document must
			include Simplified BSD License text as described in Section 4.e of
			the Trust Legal Provisions and are provided without warranty as
			described in the Simplified BSD License.
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		This document may contain material from IETF Documents or IETF
	2. Transfers from NFS Client to NFS Server . . . . . . . . . . 2		Contributions published or made publicly available before November
	3. Transfers from NFS Server to NFS Client . . . . . . . . . . 3		10, 2008. The person(s) controlling the copyright in some of this
	4. NFS Versions 2 and 3 Mapping . . . . . . . . . . . . . . . . 4		material may not have granted the IETF Trust the right to allow
	5. NFS Version 4 Mapping . . . . . . . . . . . . . . . . . . . 5		modifications of such material outside the IETF Standards Process.
	5.1. NFS Version 4 Callbacks . . . . . . . . . . . . . . . . . 7		Without obtaining an adequate license from the person(s) controlling
	6. Port Usage Considerations . . . . . . . . . . . . . . . . . 8		the copyright in such materials, this document may not be modified
	7. Security Considerations . . . . . . . . . . . . . . . . . . 8		outside the IETF Standards Process, and derivative works of it may
	8. IANA Considerations . . . . . . . . . . . . . . . . . . . . 8		not be created outside the IETF Standards Process, except to format
	9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 9		it for publication as an RFC or to translate it into languages other
	10. Normative References . . . . . . . . . . . . . . . . . . . 9		than English.
	11. Informative References . . . . . . . . . . . . . . . . . 10
	12. Authors' Addresses . . . . . . . . . . . . . . . . . . . 10
	13. Intellectual Property and Copyright Statements . . . . . 11
	Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . . 11
	Requirements Language		Table of Contents
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		1. Introduction ....................................................2
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		1.1. Requirements Language ......................................2
	document are to be interpreted as described in [RFC2119].		2. Transfers from NFS Client to NFS Server .........................3
			3. Transfers from NFS Server to NFS Client .........................3
			4. NFS Versions 2 and 3 Mapping ....................................4
			5. NFS Version 4 Mapping ...........................................6
			5.1. NFS Version 4 Callbacks ....................................7
			6. Port Usage Considerations .......................................8
			7. Security Considerations .........................................9
			8. Acknowledgments .................................................9
			9. References ......................................................9
			9.1. Normative References .......................................9
			9.2. Informative References ....................................10
	1. Introduction		1. Introduction
	The Remote Direct Memory Access (RDMA) Transport for Remote Procedure		The Remote Direct Memory Access (RDMA) Transport for Remote Procedure
	Calls (RPC) [RPCRDMA] allows an RPC client application to post		Call (RPC) [RFC5666] allows an RPC client application to post buffers
	buffers in a Chunk list for specific arguments and results from an		in a Chunk list for specific arguments and results from an RPC call.
	RPC call. The RDMA transport header conveys this list of client		The RDMA transport header conveys this list of client buffer
	buffer addresses to the server where the application can associate		addresses to the server where the application can associate them with
	them with client data and use RDMA operations to transfer the results		client data and use RDMA operations to transfer the results directly
	directly to and from the posted buffers on the client. The client		to and from the posted buffers on the client. The client and server
	and server must agree on a consistent mapping of posted buffers to		must agree on a consistent mapping of posted buffers to RPC. This
	RPC. This document details the mapping for each version of the NFS		document details the mapping for each version of the NFS protocol
	protocol [RFC1094] [RFC1813] [RFC3530] [NFSv4.1].		[RFC1094] [RFC1813] [RFC3530] [RFC5661].
			1.1. Requirements Language
			The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
			"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
			document are to be interpreted as described in [RFC2119].
	2. Transfers from NFS Client to NFS Server		2. Transfers from NFS Client to NFS Server
	The RDMA Read list, in the RDMA transport header, allows an RPC		The RDMA Read list, in the RDMA transport header, allows an RPC
	client to marshal RPC call data selectively. Large chunks of data,		client to marshal RPC call data selectively. Large chunks of data,
	such as the file data of an NFS WRITE request, MAY be referenced by		such as the file data of an NFS WRITE request, MAY be referenced by
	an RDMA Read list and be moved efficiently and directly-placed by an		an RDMA Read list and be moved efficiently and directly placed by an
	RDMA Read operation initiated by the server.		RDMA Read operation initiated by the server.
	The process of identifying these chunks for the RDMA Read list can be		The process of identifying these chunks for the RDMA Read list can be
	implemented entirely within the RPC layer. It is transparent to the		implemented entirely within the RPC layer. It is transparent to the
	upper-level protocol, such as NFS. For instance, the file data		upper-level protocol, such as NFS. For instance, the file data
	portion of an NFS WRITE request can be selected as an RDMA "chunk"		portion of an NFS WRITE request can be selected as an RDMA "chunk"
	within the eXternal Data Representation (XDR) marshaling code of RPC		within the eXternal Data Representation (XDR) marshaling code of RPC
	based on a size criterion, independently of the NFS protocol layer.		based on a size criterion, independently of the NFS protocol layer.
	The XDR unmarshaling on the receiving system can identify the		The XDR unmarshaling on the receiving system can identify the
	correspondence between Read chunks and protocol elements via the XDR		correspondence between Read chunks and protocol elements via the XDR
	position value encoded in the Read chunk entry.		position value encoded in the Read chunk entry.
	RPC RDMA Read chunks are employed by this NFS mapping to convey		RPC RDMA Read chunks are employed by this NFS mapping to convey
	specific NFS data to the server in a manner which may be directly		specific NFS data to the server in a manner that may be directly
	placed. The following sections describe this mapping for versions of		placed. The following sections describe this mapping for versions of
	the NFS protocol.		the NFS protocol.
	3. Transfers from NFS Server to NFS Client		3. Transfers from NFS Server to NFS Client
	The RDMA Write list, in the RDMA transport header, allows the client		The RDMA Write list, in the RDMA transport header, allows the client
	to post one or more buffers into which the server will RDMA Write		to post one or more buffers into which the server will RDMA Write
	designated result chunks directly. If the client sends a null Write		designated result chunks directly. If the client sends a null Write
	list, then results from the RPC call will be returned as either an		list, then results from the RPC call will be returned either as an
	inline reply, as chunks in an RDMA Read list of server-posted		inline reply, as chunks in an RDMA Read list of server-posted
	buffers, or in a client-posted reply buffer.		buffers, or in a client-posted reply buffer.
	Each posted buffer in a Write list is represented as an array of		Each posted buffer in a Write list is represented as an array of
	memory segments. This allows the client some flexibility in		memory segments. This allows the client some flexibility in
	submitting discontiguous memory segments into which the server will		submitting discontiguous memory segments into which the server will
	scatter the result. Each segment is described by a triplet		scatter the result. Each segment is described by a triplet
	consisting of the segment handle or steering tag (STag), segment		consisting of the segment handle or steering tag (STag), segment
	length, and memory address or offset.		length, and memory address or offset.
	skipping to change at page 4, line 10		skipping to change at page 4, line 18
	The sum of the segment lengths yields the total size of the buffer,		The sum of the segment lengths yields the total size of the buffer,
	which MUST be large enough to accept the result. If the buffer is		which MUST be large enough to accept the result. If the buffer is
	too small, the server MUST return an XDR encode error. The server		too small, the server MUST return an XDR encode error. The server
	MUST return the result data for a posted buffer by progressively		MUST return the result data for a posted buffer by progressively
	filling its segments, perhaps leaving some trailing segments unfilled		filling its segments, perhaps leaving some trailing segments unfilled
	or partially full if the size of the result is less than the total		or partially full if the size of the result is less than the total
	size of the buffer segments.		size of the buffer segments.
	The server returns the RDMA Write list to the client with the segment		The server returns the RDMA Write list to the client with the segment
	length fields overwritten to indicate the amount of data RDMA Written		length fields overwritten to indicate the amount of data RDMA written
	to each segment. Results returned by direct placement MUST NOT be		to each segment. Results returned by direct placement MUST NOT be
	returned by other methods, e.g., by Read chunk list or inline. If no		returned by other methods, e.g., by Read chunk list or inline. If no
	result data at all is returned for the element, the server places no		result data at all is returned for the element, the server places no
	data in the buffer(s), but does return zeroes in the segment length		data in the buffer(s), but does return zeros in the segment length
	fields corresponding to the result.		fields corresponding to the result.
	The RDMA Write list allows the client to provide multiple result		The RDMA Write list allows the client to provide multiple result
	buffers - each buffer maps to a specific result in the reply. The		buffers -- each buffer maps to a specific result in the reply. The
	NFS client and server implementations agree by specifying the mapping		NFS client and server implementations agree by specifying the mapping
	of results to buffers for each RPC procedure. The following sections		of results to buffers for each RPC procedure. The following sections
	describe this mapping for versions of the NFS protocol.		describe this mapping for versions of the NFS protocol.
	Through the use of RDMA Write lists in NFS requests, it is not		Through the use of RDMA Write lists in NFS requests, it is not
	necessary to employ the RDMA Read lists in the NFS replies, as		necessary to employ the RDMA Read lists in the NFS replies, as
	described in the RPC/RDMA protocol. This enables more efficient		described in the RPC/RDMA protocol. This enables more efficient
	operation, by avoiding the need for the server to expose buffers for		operation, by avoiding the need for the server to expose buffers for
	RDMA, and also avoiding "RDMA_DONE" exchanges. Clients MAY		RDMA, and also avoiding "RDMA_DONE" exchanges. Clients MAY
	additionally employ RDMA Reply chunks to receive entire messages, as		additionally employ RDMA Reply chunks to receive entire messages, as
	described in [RPCRDMA].		described in [RFC5666].
	4. NFS Versions 2 and 3 Mapping		4. NFS Versions 2 and 3 Mapping
	A single RDMA Write list entry MAY be posted by the client to receive		A single RDMA Write list entry MAY be posted by the client to receive
	either the opaque file data from a READ request or the pathname from		either the opaque file data from a READ request or the pathname from
	a READLINK request. The server MUST ignore a Write list for any		a READLINK request. The server MUST ignore a Write list for any
	other NFS procedure, as well as any Write list entries beyond the		other NFS procedure, as well as any Write list entries beyond the
	first in the list.		first in the list.
	Similarly, a single RDMA Read list entry MAY be posted by the client		Similarly, a single RDMA Read list entry MAY be posted by the client
	skipping to change at page 5, line 6		skipping to change at page 5, line 13
	the first in the list.		the first in the list.
	Because there are no NFS version 2 or 3 requests that transfer bulk		Because there are no NFS version 2 or 3 requests that transfer bulk
	data in both directions, it is not necessary to post requests		data in both directions, it is not necessary to post requests
	containing both Write and Read lists. Any unneeded Read or Write		containing both Write and Read lists. Any unneeded Read or Write
	lists are ignored by the server.		lists are ignored by the server.
	In the case where the outgoing request or expected incoming reply is		In the case where the outgoing request or expected incoming reply is
	larger than the maximum size supported on the connection, it is		larger than the maximum size supported on the connection, it is
	possible for the RPC layer to post the entire message or result in a		possible for the RPC layer to post the entire message or result in a
	special "RDMA_NOMSG" message type which is transferred entirely by		special "RDMA_NOMSG" message type that is transferred entirely by
	RDMA. This is implemented in RPC, below NFS and therefore has no		RDMA. This is implemented in RPC, below NFS, and therefore has no
	effect on the message contents.		effect on the message contents.
	Non-RDMA (inline) WRITE transfers MAY OPTIONALLY employ the		Non-RDMA (inline) WRITE transfers MAY OPTIONALLY employ the
	"RDMA_MSGP" padding method described in the RPC/RDMA protocol, if the		"RDMA_MSGP" padding method described in the RPC/RDMA protocol, if the
	appropriate value for the server is known to the client. Padding		appropriate value for the server is known to the client. Padding
	allows the opaque file data to arrive at the server in an aligned		allows the opaque file data to arrive at the server in an aligned
	fashion, which may improve server performance.		fashion, which may improve server performance.
	The NFS version 2 and 3 protocols are frequently limited in practice		The NFS version 2 and 3 protocols are frequently limited in practice
	to requests containing less than or equal to 8 kilobytes and 32		to requests containing less than or equal to 8 kilobytes and 32
	kilobytes of data, respectively. In these cases, it is often		kilobytes of data, respectively. In these cases, it is often
	practical to support basic operation without employing a		practical to support basic operation without employing a
	configuration exchange as discussed in [RPCRDMA]. The server MUST		configuration exchange as discussed in [RFC5666]. The server MUST
	post buffers large enough to receive the largest possible incoming		post buffers large enough to receive the largest possible incoming
	message (approximately 12KB for NFS version 2, or 36KB for NFS		message (approximately 12 KB for NFS version 2, or 36 KB for NFS
	version 3, would be vastly sufficient), and the client can post		version 3, would be vastly sufficient), and the client can post
	buffers large enough to receive replies based on the "rsize" it is		buffers large enough to receive replies based on the "rsize" it is
	using to the server, plus a fixed overhead for the RPC and NFS		using to the server, plus a fixed overhead for the RPC and NFS
	headers. Because the server MUST NOT return data in excess of this		headers. Because the server MUST NOT return data in excess of this
	size, the client can be assured of the adequacy of its posted buffer		size, the client can be assured of the adequacy of its posted buffer
	sizes.		sizes.
	Flow control is handled dynamically by the RPC RDMA protocol, and		Flow control is handled dynamically by the RPC RDMA protocol, and
	write padding is OPTIONAL and therefore MAY remain unused.		write padding is OPTIONAL and therefore MAY remain unused.
	Alternatively, if the server is administratively configured to values		Alternatively, if the server is administratively configured to values
	appropriate for all its clients, the same assurance of		appropriate for all its clients, the same assurance of
	interoperability within the domain can be made.		interoperability within the domain can be made.
	The use of a configuration protocol with NFS v2 and v3 is therefore		The use of a configuration protocol with NFS v2 and v3 is therefore
	OPTIONAL. Employing a configuration exchange may allow some		OPTIONAL. Employing a configuration exchange may allow some
	advantage to server resource management through accurately sizing		advantage to server resource management through accurately sizing
	buffers, enabling the server to know exactly how many RDMA Reads may		buffers, enabling the server to know exactly how many RDMA Reads may
	be in progress at once on the client connection, and enabling client		be in progress at once on the client connection, and enabling client
	write padding which may be desirable for certain servers when RDMA		write padding, which may be desirable for certain servers when RDMA
	Read is impractical.		Read is impractical.
	5. NFS Version 4 Mapping		5. NFS Version 4 Mapping
	This specification applies to the first minor version of NFS version		This specification applies to the first minor version of NFS version
	4 (NFSv4.0) and any subsequent minor versions that do not override		4 (NFSv4.0) and any subsequent minor versions that do not override
	this mapping.		this mapping.
	The Write list MUST be considered only for the COMPOUND procedure.		The Write list MUST be considered only for the COMPOUND procedure.
	This procedure returns results from a sequence of operations. Only		This procedure returns results from a sequence of operations. Only
	the opaque file data from an NFS READ operation, and the pathname		the opaque file data from an NFS READ operation and the pathname from
	from a READLINK operation MUST utilize entries from the Write list.		a READLINK operation MUST utilize entries from the Write list.
	If there is no Write list, i.e., the list is null, then any READ or		If there is no Write list, i.e., the list is null, then any READ or
	READLINK operations in the COMPOUND MUST return their data inline.		READLINK operations in the COMPOUND MUST return their data inline.
	The NFSv4.0 client MUST ensure in this case that any result of its		The NFSv4.0 client MUST ensure in this case that any result of its
	READ and READLINK requests will fit within its receive buffers, in		READ and READLINK requests will fit within its receive buffers, in
	order to avoid a resulting RDMA transport error upon transfer. The		order to avoid a resulting RDMA transport error upon transfer. The
	server is not required to detect this.		server is not required to detect this.
	The first entry in the Write list MUST be used by the first READ or		The first entry in the Write list MUST be used by the first READ or
	READLINK in the COMPOUND request. The next Write list entry by the		READLINK in the COMPOUND request. The next Write list entry is used
	by the next READ or READLINK, and so on. If there are more READ or		by the next READ or READLINK, and so on. If there are more READ or
	READLINK operations than Write list entries, then any remaining		READLINK operations than Write list entries, then any remaining
	operations MUST return their results inline.		operations MUST return their results inline.
	If a Write list entry is presented, then the corresponding READ or		If a Write list entry is presented, then the corresponding READ or
	READLINK MUST return its data via an RDMA Write to the buffer		READLINK MUST return its data via an RDMA Write to the buffer
	indicated by the Write list entry. If the Write list entry has zero		indicated by the Write list entry. If the Write list entry has zero
	RDMA segments, or if the total size of the segments is zero, then the		RDMA segments, or if the total size of the segments is zero, then the
	corresponding READ or READLINK operation MUST return its result		corresponding READ or READLINK operation MUST return its result
	inline.		inline.
	skipping to change at page 6, line 47		skipping to change at page 7, line 6
	A --> B --> C		A --> B --> C
	Compound request:		Compound request:
	PUTFH LOOKUP READ PUTFH LOOKUP READLINK PUTFH LOOKUP READ		PUTFH LOOKUP READ PUTFH LOOKUP READLINK PUTFH LOOKUP READ
	| | |		| | |
	v v v		v v v
	A B C		A B C
	If the client does not want to have the READLINK result returned		If the client does not want to have the READLINK result returned
	directly, then it provides a zero length array of segment triplets		directly, then it provides a zero-length array of segment triplets
	for buffer B or sets the values in the segment triplet for buffer B		for buffer B or sets the values in the segment triplet for buffer B
	to zeros so that the READLINK result MUST be returned inline.		to zeros so that the READLINK result MUST be returned inline.
	The situation is similar for RDMA Read lists sent by the client and		The situation is similar for RDMA Read lists sent by the client and
	applies to the NFSv4.0 WRITE and SYMLINK procedures as for v3.		applies to the NFSv4.0 WRITE and SYMLINK procedures as for v3.
	Additionally, inline segments too large to fit in posted buffers MAY		Additionally, inline segments too large to fit in posted buffers MAY
	be transferred in special "RDMA_NOMSG" messages.		be transferred in special "RDMA_NOMSG" messages.
	Non-RDMA (inline) WRITE transfers MAY OPTIONALLY employ the		Non-RDMA (inline) WRITE transfers MAY OPTIONALLY employ the
	"RDMA_MSGP" padding method described in the RPC/RDMA protocol, if the		"RDMA_MSGP" padding method described in the RPC/RDMA protocol, if the
	appropriate value for the server is known to the client. Padding		appropriate value for the server is known to the client. Padding
	allows the opaque file data to arrive at the server in an aligned		allows the opaque file data to arrive at the server in an aligned
	fashion, which may improve server performance. In order to ensure		fashion, which may improve server performance. In order to ensure
	accurate alignment for all data, it is likely that the client will		accurate alignment for all data, it is likely that the client will
	restrict its use of OPTIONAL padding to COMPOUND requests containing		restrict its use of OPTIONAL padding to COMPOUND requests containing
	only a single WRITE operation.		only a single WRITE operation.
	Unlike NFS versions 2 and 3, the maximum size of an NFS version 4		Unlike NFS versions 2 and 3, the maximum size of an NFS version 4
	COMPOUND is not bounded, even when RDMA chunks are in use. While it		COMPOUND is not bounded, even when RDMA chunks are in use. While it
	might appear that a configuration protocol exchange (such as the one		might appear that a configuration protocol exchange (such as the one
	described in [RPCRDMA]) would help, in fact the layering issues		described in [RFC5666]) would help, in fact the layering issues
	involved in building COMPOUNDs by NFS make such a mechanism		involved in building COMPOUNDs by NFS make such a mechanism
	unworkable.		unworkable.
	However, typical NFS version 4 clients rarely issue such problematic		However, typical NFS version 4 clients rarely issue such problematic
	requests. In practice, they behave in much more predictable ways, in		requests. In practice, they behave in much more predictable ways, in
	fact most still support the traditional rsize/wsize mount parameters.		fact most still support the traditional rsize/wsize mount parameters.
	Therefore, most NFS version 4 clients function over RPC/RDMA in the		Therefore, most NFS version 4 clients function over RPC/RDMA in the
	same way as NFS versions 2 and 3, operationally.		same way as NFS versions 2 and 3, operationally.
	There are however advantages to allowing both client and server to		There are however advantages to allowing both client and server to
	operate with prearranged size constraints, for example use of the		operate with prearranged size constraints, for example, use of the
	sizes to better manage the server's response cache. An extension to		sizes to better manage the server's response cache. An extension to
	NFS version 4 supporting a more comprehensive exchange of upper layer		NFS version 4 supporting a more comprehensive exchange of upper-layer
	parameters is part of [NFSv4.1].		parameters is part of [RFC5661].
	5.1. NFS Version 4 Callbacks		5.1. NFS Version 4 Callbacks
	The NFS version 4 protocols support server-initiated callbacks to		The NFS version 4 protocols support server-initiated callbacks to
	selected clients, in order to notify them of events such as recalled		selected clients, in order to notify them of events such as recalled
	delegations, etc. These callbacks present no particular issue to		delegations, etc. These callbacks present no particular issue to
	being framed over RPC/RDMA, since such callbacks do not carry bulk		being framed over RPC/RDMA, since such callbacks do not carry bulk
	data such as NFS READ or NFS WRITE. They MAY be transmitted inline		data such as NFS READ or NFS WRITE. They MAY be transmitted inline
	via RDMA_MSG, or if the callback message or its reply overflow the		via RDMA_MSG, or if the callback message or its reply overflow the
	negotiated buffer sizes for a callback connection, they MAY be		negotiated buffer sizes for a callback connection, they MAY be
	transferred via the RDMA_NOMSG method as described above for other		transferred via the RDMA_NOMSG method as described above for other
	exchanges.		exchanges.
	One special case is noteworthy: in NFS version 4.1, the callback		One special case is noteworthy: in NFS version 4.1, the callback
	channel is optionally negotiated to be on the same connection as one		channel is optionally negotiated to be on the same connection as one
	used for client requests. In this case, and because the XID is		used for client requests. In this case, and because the transaction
	present in the RPC/RDMA header, the client MUST ascertain whether the		ID (XID) is present in the RPC/RDMA header, the client MUST ascertain
	message is in fact an RPC REPLY, and therefore a reply to a prior		whether the message is in fact an RPC REPLY, and therefore a reply to
	request and carrying its XID, before processing it as such. By the		a prior request and carrying its XID, before processing it as such.
	same token, the server MUST ascertain whether an incoming message on		By the same token, the server MUST ascertain whether an incoming
	such a callback-eligible connection is an RPC CALL, before optionally		message on such a callback-eligible connection is an RPC CALL, before
	processing the XID.		optionally processing the XID.
	In the callback case, the XID present in the RPC/RDMA header will		In the callback case, the XID present in the RPC/RDMA header will
	potentially have any value which may (or may not) collide with an XID		potentially have any value, which may (or may not) collide with an
	used by the client for a previous or future request. The client and		XID used by the client for a previous or future request. The client
	server MUST inspect the RPC component of the message to determine its		and server MUST inspect the RPC component of the message to determine
	potential disposition as either an RPC CALL or RPC REPLY, prior to		its potential disposition as either an RPC CALL or RPC REPLY, prior
	processing this XID, and MUST NOT reject or accept it without also		to processing this XID, and MUST NOT reject or accept it without also
	determining the proper context.		determining the proper context.
	6. Port Usage Considerations		6. Port Usage Considerations
	NFS use of direct data placement introduces a need for an additional		NFS use of direct data placement introduces a need for an additional
	NFS port number assignment for networks which share traditional UDP		NFS port number assignment for networks that share traditional UDP
	and TCP port spaces with RDMA services. The iWARP [RFC5041]		and TCP port spaces with RDMA services. The iWARP [RFC5041]
	[RFC5040] protocol is such an example (Infiniband is not).		[RFC5040] protocol is such an example (InfiniBand is not).
	NFS servers for versions 2 and 3 [RFC1094] [RFC1813] traditionally		NFS servers for versions 2 and 3 [RFC1094] [RFC1813] traditionally
	listen for clients on UDP and TCP port 2049, and additionally, they		listen for clients on UDP and TCP port 2049, and additionally, they
	register these with the portmapper and/or rpcbind [RFC1833] service.		register these with the portmapper and/or rpcbind [RFC1833] service.
	However, [RFC3530] requires NFS servers for version 4 to listen on		However, [RFC3530] requires NFS servers for version 4 to listen on
	TCP port 2049, and they are not required to register.		TCP port 2049, and they are not required to register.
	An NFS version 2 or version 3 server supporting RPC/RDMA on such a		An NFS version 2 or version 3 server supporting RPC/RDMA on such a
	network and registering itself with the RPC portmapper MAY choose an		network and registering itself with the RPC portmapper MAY choose an
	arbitrary port, or MAY use the alternative well-known port number for		arbitrary port, or MAY use the alternative well-known port number for
	its RPC/RDMA service. The chosen port MAY be registered with the RPC		its RPC/RDMA service. The chosen port MAY be registered with the RPC
	portmapper under the netid assigned by the requirement in [RPCRDMA].		portmapper under the netid assigned by the requirement in [RFC5666].
	An NFS version 4 server supporting RPC/RDMA on such a network MUST		An NFS version 4 server supporting RPC/RDMA on such a network MUST
	use the alternative well-known port number for its RPC/RDMA service.		use the alternative well-known port number for its RPC/RDMA service.
	Clients SHOULD connect to this well-known port without consulting the		Clients SHOULD connect to this well-known port without consulting the
	RPC portmapper (as for NFSv4/TCP).		RPC portmapper (as for NFSv4/TCP).
	The port number assigned to an NFS service over an RPC/RDMA transport		The port number assigned to an NFS service over an RPC/RDMA transport
	is available from the IANA port registry [RFC3232].		is available from the IANA port registry [RFC3232].
	7. Security Considerations		7. Security Considerations
	The RDMA transport for RPC [RPCRDMA] supports all RPC [RFC1831bis]		The RDMA transport for RPC [RFC5666] supports all RPC [RFC5531]
	security models, including RPCSEC_GSS [RFC2203] security and link-		security models, including RPCSEC_GSS [RFC2203] security and link-
	level security. The choice of RDMA Read and RDMA Write to return RPC		level security. The choice of RDMA Read and RDMA Write to return RPC
	argument and results, respectively, does not affect this, since it		argument and results, respectively, does not affect this, since it
	only changes the method of data transfer. Specifically, the		only changes the method of data transfer. Specifically, the
	requirements of [RPCRDMA] ensure that this choice does not introduce		requirements of [RFC5666] ensure that this choice does not introduce
	new vulnerabilities.		new vulnerabilities.
	Because this document defines only the binding of the NFS protocols		Because this document defines only the binding of the NFS protocols
	atop [RPCRDMA], all relevant security considerations are therefore to		atop [RFC5666], all relevant security considerations are therefore to
	be described at that layer.		be described at that layer.
	8. IANA Considerations		8. Acknowledgments
	This document has no IANA considerations.
	9. Acknowledgments
	The authors would like to thank Dave Noveck and Chet Juszczak for		The authors would like to thank Dave Noveck and Chet Juszczak for
	their contributions to this document.		their contributions to this document.
	10. Normative References		9. References
	[RFC2119]
	S. Bradner, "Key words for use in RFCs to Indicate Requirement
	Levels",
	Best Current Practice,
	BCP 14, RFC 2119, March 1997.
	[RFC1094]
	"NFS: Network File System Protocol Specification",
	(NFS version 2) Informational RFC,
	http://www.ietf.org/rfc/rfc1094.txt
	[RFC1831bis]
	R. Thurlow, Ed., "RPC: Remote Procedure Call Protocol
	Specification Version 2",
	Standards Track RFC
	[RFC1813]
	B. Callaghan, B. Pawlowski, P. Staubach, "NFS Version 3 Protocol
	Specification",
	Informational RFC,
	http://www.ietf.org/rfc/rfc1813.txt
	[RFC1833]
	R. Srinivasan, "Binding Protocols for ONC RPC Version 2",
	Standards Track RFC,
	http://www.ietf.org/rfc/rfc1833.txt
	[RFC3530]
	S. Shepler, et al., "NFS version 4 Protocol",
	Standards Track RFC,
	http://www.ietf.org/rfc/rfc3530.txt
	[NFSv4.1]
	S. Shepler et al., ed., "NFSv4 Minor Version 1"
	Internet Draft Work in Progress,
	draft-ietf-nfsv4-minorversion1
	[RFC2203]		9.1. Normative References
	M. Eisler, A. Chiu, L. Ling, "RPCSEC_GSS Protocol Specification",
	Standards Track RFC,
	http://www.ietf.org/rfc/rfc2203.txt
	11. Informative References		[RFC1094] Sun Microsystems, "NFS: Network File System Protocol
			specification", RFC 1094, March 1989.
	[RFC3232]		[RFC1813] Callaghan, B., Pawlowski, B., and P. Staubach, "NFS
	Internet Assigned Numbers Authority (IANA),		Version 3 Protocol Specification", RFC 1813, June 1995.
	Port Registry database,
	http://www.ietf.org/rfc/rfc3232.txt
	http://www.iana.org/assignments/port-numbers
	[RPCRDMA]		[RFC1833] Srinivasan, R., "Binding Protocols for ONC RPC Version 2",
	T. Talpey, B. Callaghan, "Remote Direct Memory Access Transport		RFC 1833, August 1995.
	for Remote Procedure Call"
	Internet Draft Work in Progress,
	draft-ietf-nfsv4-rpcrdma
	[RFC5041]		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	H. Shah et al., "Direct Data Placement over Reliable Transports",		Requirement Levels", BCP 14, RFC 2119, March 1997.
	Standards Track RFC
	[RFC5040]		[RFC2203] Eisler, M., Chiu, A., and L. Ling, "RPCSEC_GSS Protocol
	R. Recio et al., "A Remote Direct Memory Access Protocol		Specification", RFC 2203, September 1997.
	Specification",
	Standards Track RFC
	12. Authors' Addresses		[RFC3530] Shepler, S., Callaghan, B., Robinson, D., Thurlow, R.,
			Beame, C., Eisler, M., and D. Noveck, "Network File System
			(NFS) version 4 Protocol", RFC 3530, April 2003.
	Tom Talpey		[RFC5531] Thurlow, R., "RPC: Remote Procedure Call Protocol
	Network Appliance, Inc.		Specification Version 2", RFC 5531, May 2009.
	1601 Trapelo Road, #16
	Waltham, MA 02451 USA
	Phone: +1 781 768 5329		[RFC5661] Shepler, S., Ed., Eisler, M., Ed., and D. Noveck, Ed.,
	EMail: thomas.talpey@netapp.com		"Network File System (NFS) Version 4 Minor Version 1
	Brent Callaghan		Protocol", RFC 5661, January 2010.
	Apple Computer, Inc.
	MS: 302-4K
	2 Infinite Loop
	Cupertino, CA 95014 USA
	EMail: brentc@apple.com		9.2. Informative References
	13. Intellectual Property and Copyright Statements		[RFC3232] Reynolds, J., Ed., "Assigned Numbers: RFC 1700 is Replaced
			by an On-line Database", RFC 3232, January 2002.
	Full Copyright Statement		[RFC5040] Recio, R., Metzler, B., Culley, P., Hilland, J., and D.
			Garcia, "A Remote Direct Memory Access Protocol
			Specification", RFC 5040, October 2007.
	Copyright (C) The IETF Trust (2008).		[RFC5041] Shah, H., Pinkerton, J., Recio, R., and P. Culley, "Direct
			Data Placement over Reliable Transports", RFC 5041,
			October 2007.
	This document is subject to the rights, licenses and restrictions		[RFC5666] Talpey, T. and B. Callaghan, "Remote Direct Memory Access
	contained in BCP 78, and except as set forth therein, the authors		Transport for Remote Procedure Call", RFC 5666, January
	retain all their rights.		2010.
	This document and the information contained herein are provided on		Authors' Addresses
	an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
	REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE
	IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL
	WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY
	WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE
	ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS
	FOR A PARTICULAR PURPOSE.
	Intellectual Property		Tom Talpey
	The IETF takes no position regarding the validity or scope of any		170 Whitman St.
	Intellectual Property Rights or other rights that might be claimed		Stow, MA 01775 USA
	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		EMail: tmtalpey@gmail.com
	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		Brent Callaghan
	copyrights, patents or patent applications, or other proprietary		Apple Computer, Inc.
	rights that may cover technology that may be required to implement		MS: 302-4K
	this standard. Please address the information to the IETF at ietf-		2 Infinite Loop
	ipr@ietf.org.		Cupertino, CA 95014 USA
	Acknowledgment		EMail: brentc@apple.com
	Funding for the RFC Editor function is provided by the IETF
	Administrative Support Activity (IASA).
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