draft-ietf-nfsv4-rfc5667bis-01.txt   draft-ietf-nfsv4-rfc5667bis-02.txt 
Network File System Version 4 C. Lever, Ed. Network File System Version 4 C. Lever, Ed.
Internet-Draft Oracle Internet-Draft Oracle
Obsoletes: 5667 (if approved) June 30, 2016 Obsoletes: 5667 (if approved) August 25, 2016
Intended status: Standards Track Intended status: Standards Track
Expires: January 1, 2017 Expires: February 26, 2017
Network File System (NFS) Upper Layer Binding To RPC-Over-RDMA Network File System (NFS) Upper Layer Binding To RPC-Over-RDMA
draft-ietf-nfsv4-rfc5667bis-01 draft-ietf-nfsv4-rfc5667bis-02
Abstract Abstract
This document specifies the Upper Layer Bindings of Network File This document specifies Upper Layer Bindings of Network File System
System (NFS) protocol versions to RPC-over-RDMA transports. Such (NFS) protocol versions to RPC-over-RDMA transports. These bindings
Upper Layer Bindings are required to enable RPC-based protocols to are required to enable RPC-based protocols to use direct data
use direct data placement when conveying large data payloads on RPC- placement on RPC-over-RDMA transports. This document obsoletes RFC
over-RDMA transports. This document obsoletes RFC 5667. 5667.
Status of This Memo Status of This Memo
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provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on January 1, 2017. This Internet-Draft will expire on February 26, 2017.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 1.1. Changes Since RFC 5667 . . . . . . . . . . . . . . . . . 3
1.2. Changes Since RFC 5667 . . . . . . . . . . . . . . . . . 3 1.2. Extending This Upper Layer Binding . . . . . . . . . . . 4
1.3. Planned Changes To This Document . . . . . . . . . . . . 4 1.3. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Conveying NFS Operations On RPC-Over-RDMA Transports . . . . 4 2. Conveying NFS Operations On RPC-Over-RDMA Transports . . . . 4
2.1. Use Of The Read List . . . . . . . . . . . . . . . . . . 4 2.1. Use Of The Read List . . . . . . . . . . . . . . . . . . 4
2.2. Use Of The Write List . . . . . . . . . . . . . . . . . . 5 2.2. Use Of The Write List . . . . . . . . . . . . . . . . . . 4
2.3. Construction Of Individual Chunks . . . . . . . . . . . . 5 2.3. Construction Of Individual Chunks . . . . . . . . . . . . 5
2.4. Use Of Long Calls And Replies . . . . . . . . . . . . . . 5 2.4. Use Of Long Calls And Replies . . . . . . . . . . . . . . 5
3. NFS Versions 2 And 3 Upper Layer Binding . . . . . . . . . . 5 3. NFS Versions 2 And 3 Upper Layer Binding . . . . . . . . . . 5
4. NFS Version 4 Upper Layer Binding . . . . . . . . . . . . . . 6 4. NFS Version 4 Upper Layer Binding . . . . . . . . . . . . . . 6
4.1. NFS Version 4 COMPOUND Considerations . . . . . . . . . . 7 4.1. DDP-Eligibility . . . . . . . . . . . . . . . . . . . . . 6
4.2. NFS Version 4 Callbacks . . . . . . . . . . . . . . . . . 8 4.2. Reply Size Estimation . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 4.3. NFS Version 4 COMPOUND Considerations . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 9 4.4. NFS Version 4 Callback . . . . . . . . . . . . . . . . . 9
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 6. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8.1. Normative References . . . . . . . . . . . . . . . . . . 9 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10
8.2. Informative References . . . . . . . . . . . . . . . . . 10 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 11 8.1. Normative References . . . . . . . . . . . . . . . . . . 10
8.2. Informative References . . . . . . . . . . . . . . . . . 11
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction 1. Introduction
Remote Direct Memory Access Transport for Remote Procedure Call, An RPC-over-RDMA transport, such as defined in
Version One [I-D.ietf-nfsv4-rfc5666bis] (RPC-over-RDMA) enables the [I-D.ietf-nfsv4-rfc5666bis], may employ direct data placement to
use of direct data placement to accelerate the transmission of large transmit large data payloads associated with RPC transactions. Each
data payloads associated with RPC transactions. RPC-over-RDMA transport header conveys lists of memory locations
corresponding to XDR data items defined in an Upper Layer Protocol
Each RPC-over-RDMA transport header can convey lists of memory (such as NFS).
locations involved in direct transfers of data payloads. These
memory locations correspond to XDR data items defined in an Upper
Layer Protocol (such as NFS).
To facilitate interoperation, RPC client and server implementations To facilitate interoperation, RPC client and server implementations
must agree on what XDR data items in which RPC procedures are must agree in advance on what XDR data items in which RPC procedures
eligible for direct data placement (DDP). are eligible for direct data placement (DDP). This document contains
material required of Upper Layer Bindings, as specified in
This document specifies the set of XDR data items in each of the [I-D.ietf-nfsv4-rfc5666bis], for the following NFS protocol versions:
following NFS protocol versions that are eligible for DDP. It also
contains additional material required of Upper Layer Bindings as
specified in [I-D.ietf-nfsv4-rfc5666bis].
o NFS Version 2 [RFC1094] o NFS Version 2 [RFC1094]
o NFS Version 3 [RFC1813] o NFS Version 3 [RFC1813]
o NFS Version 4.0 [RFC7530] o NFS Version 4.0 [RFC7530]
o NFS Version 4.1 [RFC5661] o NFS Version 4.1 [RFC5661]
o NFS Version 4.2 [I-D.ietf-nfsv4-minorversion2] o NFS Version 4.2 [I-D.ietf-nfsv4-minorversion2]
The Upper Layer Binding specified in this document can be extended to 1.1. Changes Since RFC 5667
cover the addition of new DDP-eligible XDR data items defined by
versions of the NFS version 4 protocol specified after this document
has been ratified.
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].
1.2. Changes Since RFC 5667
Corrections and updates made necessary by new language in Corrections and updates made necessary by new language in
[I-D.ietf-nfsv4-rfc5666bis] has been introduced. For example, [I-D.ietf-nfsv4-rfc5666bis] have been introduced. For example,
references to deprecated features of RPC-over-RDMA Version One, such references to deprecated features of RPC-over-RDMA Version One, such
as RDMA_MSGP, and the use of the Read list for handling RPC replies, as RDMA_MSGP, and the use of the Read list for handling RPC replies,
has been removed. The term "mapping" has been replaced with the term has been removed. The term "mapping" has been replaced with the term
"binding" or "Upper Layer Binding" throughout the document. Material "binding" or "Upper Layer Binding" throughout the document. Material
that duplicates what is in [I-D.ietf-nfsv4-rfc5666bis] has been that duplicates what is in [I-D.ietf-nfsv4-rfc5666bis] has been
deleted. deleted.
Material required by [I-D.ietf-nfsv4-rfc5666bis] for Upper Layer Material required by [I-D.ietf-nfsv4-rfc5666bis] for Upper Layer
Bindings that was not present in [RFC5667] has been added, including Bindings that was not present in [RFC5667] has been added, including
discussion of how each NFS version properly estimates the maximum discussion of how each NFS version properly estimates the maximum
skipping to change at page 3, line 51 skipping to change at page 3, line 36
o Ambiguous or erroneous uses of RFC2119 terms have been corrected. o Ambiguous or erroneous uses of RFC2119 terms have been corrected.
o References to specific data movement mechanisms have been made o References to specific data movement mechanisms have been made
generic or removed. generic or removed.
o References to obsolete RFCs have been replaced. o References to obsolete RFCs have been replaced.
o Technical corrections have been made. For example, the mention of o Technical corrections have been made. For example, the mention of
12KB and 36KB inline thresholds have been removed. The reference 12KB and 36KB inline thresholds have been removed. The reference
to a non-existant NFS version 4 SYMLINK operation has been to a non-existant NFS version 4 SYMLINK operation has been
replaced with NFS version 4 CREATE(NF4LNK). replaced with NFS version 4 CREATE(NF4LNK). The discussion of NFS
version 4 COMPOUND handling has been completed.
o An IANA Considerations Section has replaced the "Port Usage o An IANA Considerations Section has replaced the "Port Usage
Considerations" Section. Considerations" Section.
o Code excerpts have been removed, and figures have been modernized. o Code excerpts have been removed, and figures have been modernized.
o Language inconsistent with or contradictory to o Language inconsistent with or contradictory to
[I-D.ietf-nfsv4-rfc5666bis] has been removed from Sections 2 and [I-D.ietf-nfsv4-rfc5666bis] has been removed from Sections 2 and
3, and both Sections have been combined into Section 2 in the 3, and both Sections have been combined into Section 2 in the
present document. present document.
o An explicit discussion of NFSv4.0 and NFSv4.1 backchannel o An explicit discussion of NFSv4.0 and NFSv4.1 backchannel
operation will replace the previous treatment of callback operation will replace the previous treatment of callback
operations. No NFSv4.x callback operation is DDP-eligible. operations. No NFSv4.x callback operation is DDP-eligible.
o The binding for NFSv4.1 has been completed. No additional DDP- o The binding for NFSv4.1 has been completed. No DDP-eligible
eligible operations exist in NFSv4.1. operations exist in NFSv4.1 that did not exist in NFSv4.0.
o A binding for NFSv4.2 has been added that includes discussion of o A binding for NFSv4.2 has been added that includes discussion of
new data-bearing operations like READ_PLUS. new data-bearing operations like READ_PLUS.
1.3. Planned Changes To This Document 1.2. Extending This Upper Layer Binding
The following changes are planned, relative to [RFC5667]:
o The discussion of NFS version 4 COMPOUND handling will be As stated earlier, RPC programs such as NFS are required to have an
completed. Upper Layer Binding specification to interoperate on RPC-over-RDMA
transports [I-D.ietf-nfsv4-rfc5666bis]. The Upper Layer Binding
specified in this document can be extended to cover versions of the
NFS version 4 protocol specified after NFS version 4 minor version 2
via standards action. This includes NFSv4 extensions that are
documented separately from a new minor version.
o Remarks about handling DDP-eligibility violations will be 1.3. Requirements Language
introduced.
o A discussion of how the NFS binding to RPC-over-RDMA is extended The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
by standards action will be added. "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2. Conveying NFS Operations On RPC-Over-RDMA Transports 2. Conveying NFS Operations On RPC-Over-RDMA Transports
Definitions of terminology and a general discussion of how RPC-over- Definitions of terminology and a general discussion of how RPC-over-
RDMA is used to convey RPC transactions can be found in RDMA is used to convey RPC transactions can be found in
[I-D.ietf-nfsv4-rfc5666bis]. In this section, these general [I-D.ietf-nfsv4-rfc5666bis]. In this section, these general
principals are applied to the specifics of the NFS protocol. principals are applied to the specifics of the NFS protocol.
2.1. Use Of The Read List 2.1. Use Of The Read List
The Read list in each RPC-over-RDMA transport header represents a set The Read list in each RPC-over-RDMA transport header represents a set
of memory regions containing DDP-eligible NFS argument data. Large of memory regions containing DDP-eligible NFS argument data. Large
data items, such as the file data payload of an NFS WRITE request, data items, such as the data payload of an NFS WRITE request, are
are referenced by the Read list and placed directly into server referenced by the Read list. The server places these directly into
memory. its memory.
XDR unmarshaling code on the NFS server identifies the correspondence XDR unmarshaling code on the NFS server identifies the correspondence
between Read chunks and particular NFS arguments via the chunk between Read chunks and particular NFS arguments via the chunk
Position value encoded in each Read chunk. Position value encoded in each Read chunk.
2.2. Use Of The Write List 2.2. Use Of The Write List
The Write list in each RPC-over-RDMA transport header represents a The Write list in each RPC-over-RDMA transport header represents a
set of memory regions that can receive DDP-eligible NFS result data. set of memory regions that can receive DDP-eligible NFS result data.
Large data items such as the payload of an NFS READ request are Large data items such as the payload of an NFS READ request are
referenced by the Write list and placed directly into client memory. referenced by the Write list. The server places these directly into
client memory.
Each Write chunk corresponds to a specific XDR data item in an NFS Each Write chunk corresponds to a specific XDR data item in an NFS
reply. This document specifies how NFS client and server reply. This document specifies how NFS client and server
implementations identify the correspondence between Write chunks and implementations identify the correspondence between Write chunks and
each XDR result. XDR results.
2.3. Construction Of Individual Chunks 2.3. Construction Of Individual Chunks
Each Read chunk is represented as a list of segments at the same XDR Each Read chunk is represented as a list of segments at the same XDR
Position, and each Write chunk is represented as an array of Position, and each Write chunk is represented as an array of
segments. An NFS client thus has the flexibility to advertise a set segments. An NFS client thus has the flexibility to advertise a set
of discontiguous memory regions in which to send or receive a single of discontiguous memory regions in which to send or receive a single
DDP-eligible data item. DDP-eligible data item.
2.4. Use Of Long Calls And Replies 2.4. Use Of Long Calls And Replies
Small RPC messages are conveyed using RDMA Send operations which are Small RPC messages are conveyed using RDMA Send operations which are
of limited size. If an NFS request is too large to be conveyed via of limited size. If an NFS request is too large to be conveyed via
an RDMA Send, and there are no DDP-eligible data items that can be an RDMA Send, and there are no DDP-eligible data items that can be
removed, an NFS client must send the request using a Long Call. The removed, an NFS client must send the request using a Long Call. The
entire NFS request is sent in a special Read chunk. entire NFS request is sent in a special Read chunk called a Position-
Zero Read chunk.
If a client expects that an NFS reply will be too large to be If a client predicts that the maximum size of an NFS reply is too
conveyed via an RDMA Send, it provides a Reply chunk in the RPC-over- large to be conveyed via an RDMA Send, it provides a Reply chunk in
RDMA transport header conveying the NFS request. The server can the RPC-over-RDMA transport header conveying the NFS request. The
place the entire NFS reply in the Reply chunk. server can place the entire NFS reply in the Reply chunk.
These are described in more detail in [I-D.ietf-nfsv4-rfc5666bis]. These special chunks are described in more detail in
[I-D.ietf-nfsv4-rfc5666bis].
3. NFS Versions 2 And 3 Upper Layer Binding 3. NFS Versions 2 And 3 Upper Layer Binding
An NFS client MAY send a single Read chunk to supply opaque file data An NFS client MAY send a single Read chunk to supply opaque file data
for an NFS WRITE procedure, or the pathname for an NFS SYMLINK for an NFS WRITE procedure, or the pathname for an NFS SYMLINK
procedure. For all other NFS procedures, the server MUST ignore Read procedure. For all other NFS procedures, NFS servers MUST ignore
chunks that have a non-zero value in their Position fields, and Read Read chunks that have a non-zero value in their Position fields, and
chunks beyond the first in the Read list. Read chunks beyond the first in the Read list.
Similarly, an NFS client MAY provide a single Write chunk to receive Similarly, an NFS client MAY provide a single Write chunk to receive
either opaque file data from an NFS READ procedure, or the pathname either opaque file data from an NFS READ procedure, or the pathname
from an NFS READLINK procedure. The server MUST ignore the Write from an NFS READLINK procedure. NFS servers MUST ignore the Write
list for any other NFS procedure, and any Write chunks beyond the list for any other NFS procedure, and any Write chunks beyond the
first in the Write list. first in the Write list.
There are no NFS version 2 or 3 procedures that have DDP-eligible There are no NFS version 2 or 3 procedures that have DDP-eligible
data items in both their Call and Reply. However, if an NFS client data items in both their Call and Reply. However, when an NFS client
is sending a Long Call or Reply, it MAY provide a combination of Read sends a Long Call or Reply, it MAY provide a combination of Read
list, Write list, and/or a Reply chunk in the same transaction. list, Write list, and/or a Reply chunk in the same RPC-over-RDMA
header.
If an NFS client has not provided enough bytes in a Read list to
match the size of a DDP-eligible NFS argument data item, or if an NFS
client has not provided enough Write list resources to handle an NFS
WRITE or READLINK reply, or if the client has not provided a large
enough Reply chunk to convey an NFS reply, the server MUST return one
of:
o An RPC-over-RDMA message of type RDMA_ERROR, with the rdma_xid
field set to the XID of the matching NFS Call, and the rdma_error
field set to ERR_CHUNK; or
o An RPC message with the mtype field set to REPLY, the stat field
set to MSG_ACCEPTED, and the accept_stat field set to
GARBAGE_ARGS.
NFS clients already successfully estimate the maximum reply size of NFS clients already successfully estimate the maximum reply size of
each operation in order to provide an adequate set of buffers to each operation in order to provide an adequate set of buffers to
receive each NFS reply. An NFS client provides a Reply chunk when receive each NFS reply. An NFS client provides a Reply chunk when
the maximum possible reply size is larger than the client's responder the maximum possible reply size is larger than the client's responder
inline threshold. inline threshold.
How does the server respond if the client has not provided enough
Write list resources to handle an NFS WRITE or READLINK reply? How
does the server respond if the client has not provided enough Reply
chunk resources to handle an NFS reply?
4. NFS Version 4 Upper Layer Binding 4. NFS Version 4 Upper Layer Binding
This specification applies to NFS Version 4.0 [RFC7530], NFS Version This specification applies to NFS Version 4.0 [RFC7530], NFS Version
4.1 [RFC5661], and NFS Version 4.2 [I-D.ietf-nfsv4-minorversion2]. 4.1 [RFC5661], and NFS Version 4.2 [I-D.ietf-nfsv4-minorversion2].
It also applies to the callback protocols associated with each of It also applies to the callback protocols associated with each of
these minor versions. these minor versions.
4.1. DDP-Eligibility
An NFS client MAY send a Read chunk to supply opaque file data for a An NFS client MAY send a Read chunk to supply opaque file data for a
WRITE operation or the pathname for a CREATE(NF4LNK) operation in an WRITE operation or the pathname for a CREATE(NF4LNK) operation in an
NFS version 4 COMPOUND procedure. An NFS client MUST NOT send a Read NFS version 4 COMPOUND procedure. An NFS client MUST NOT send a Read
chunk that corresponds with any other XDR data item in any other NFS chunk that corresponds with any other XDR data item in any other NFS
version 4 operation. version 4 operation in an NFS version 4 COMPOUND procedure, or in an
NFS version 4 NULL procedure.
Similarly, an NFS client MAY provide a Write chunk to receive either Similarly, an NFS client MAY provide a Write chunk to receive either
opaque file data from a READ operation, NFS4_CONTENT_DATA from a opaque file data from a READ operation, NFS4_CONTENT_DATA from a
READ_PLUS operation, or the pathname from a READLINK operation in an READ_PLUS operation, or the pathname from a READLINK operation in an
NFS version 4 COMPOUND procedure. An NFS client MUST NOT provide a NFS version 4 COMPOUND procedure. An NFS client MUST NOT provide a
Write chunk that corresponds with any other XDR data item in any Write chunk that corresponds with any other XDR data item in any
other NFS version 4 operation. other NFS version 4 operation in an NFS version 4 COMPOUND procedure,
or in an NFS version 4 NULL procedure.
There is no prohibition against an NFS version 4 COMPOUND procedure There is no prohibition against an NFS version 4 COMPOUND procedure
constructed with both a READ and WRITE operation, say. Thus it is constructed with both a READ and WRITE operation, say. Thus it is
possible for NFS version 4 COMPOUND procedures to use both the Read possible for NFS version 4 COMPOUND procedures to use both the Read
list and Write list simultaneously. An NFS client MAY provide a Read list and Write list simultaneously. An NFS client MAY provide a Read
list and a Write list in the same transaction if it is sending a Long list and a Write list in the same transaction if it is sending a Long
Call or Reply. Call or Reply.
Some remarks need to be made about how NFS version 4 clients estimate If an NFS client has not provided enough bytes in a Read list to
reply size, and how DDP-eligibility violations are reported. match the size of a DDP-eligible NFS argument data item, or if an NFS
client has not provided enough Write list resources to handle a WRITE
or READLINK operation, or if the client has not provided a large
enough Reply chunk to convey an NFS reply, the server MUST return one
of:
4.1. NFS Version 4 COMPOUND Considerations o An RPC-over-RDMA message of type RDMA_ERROR, with the rdma_xid
field set to the XID of the matching NFS Call, and the rdma_error
field set to ERR_CHUNK; or
o An RPC message with the mtype field set to REPLY, the stat field
set to MSG_ACCEPTED, and the accept_stat field set to
GARBAGE_ARGS.
4.2. Reply Size Estimation
An NFS client provides a Reply chunk when the maximum possible reply
size is larger than the client's responder inline threshold. NFS
clients successfully estimate the maximum reply size of most
operations in order to provide an adequate set of buffers to receive
each NFS reply.
There are certain NFSv4 data items whose size cannot be reliably
estimated by clients, however, because there is no protocol-specified
size limit on these structures. These include but are not limited to
opaque types such as the attrlist4 field; fields containing ACLs such
as fattr4_acl, fattr4_dacl, fattr4_sacl; fields in the fs_locations4
and fs_locations_info4 data structures; and opaque fields loc_body,
loh_body, da_addr_body, lou_body, lrf_body, fattr_layout_types and
fs_layout_types, which pertain to pNFS layout metadata.
4.3. NFS Version 4 COMPOUND Considerations
An NFS version 4 COMPOUND procedure supplies arguments for a sequence An NFS version 4 COMPOUND procedure supplies arguments for a sequence
of operations, and returns results from that sequence. A client MAY of operations, and returns results from that sequence. A client MAY
construct an NFS version 4 COMPOUND procedure that uses more than one construct an NFS version 4 COMPOUND procedure that uses more than one
chunk in either the Read list or Write list. The NFS client provides chunk in either the Read list or Write list. The NFS client provides
XDR Position values in each Read chunk to disambiguate which chunk is XDR Position values in each Read chunk to disambiguate which chunk is
associated with which XDR data item. associated with which XDR data item.
However NFS server and client implementations must agree in advance However NFS server and client implementations must agree in advance
on how to pair Write chunks with returned result data items. The on how to pair Write chunks with returned result data items. The
skipping to change at page 8, line 19 skipping to change at page 9, line 7
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. However, typical NFS version 4 clients COMPOUND is not bounded. However, typical NFS version 4 clients
rarely issue such problematic requests. In practice, NFS version 4 rarely issue such problematic requests. In practice, NFS version 4
clients behave in much more predictable ways. Rsize and wsize apply clients behave in much more predictable ways. Rsize and wsize apply
to COMPOUND operations by capping the total amount of data payload to COMPOUND operations by capping the total amount of data payload
allowed in each COMPOUND. An extension to NFS version 4 supporting a allowed in each COMPOUND. An extension to NFS version 4 supporting a
comprehensive exchange of upper-layer message size parameters is part comprehensive exchange of upper-layer message size parameters is part
of [RFC5661]. of [RFC5661].
4.2. NFS Version 4 Callbacks 4.4. NFS Version 4 Callback
The NFS version 4 protocols support server-initiated callbacks to The NFS version 4 protocols support server-initiated callbacks to
notify clients of events such as recalled delegations. There are no notify clients of events such as recalled delegations. There are no
DDP-eligible data items in callback protocols associated with DDP-eligible data items in callback protocols associated with
NFSv4.0, NFSv4.1, or NFSv4.2. NFSv4.0, NFSv4.1, or NFSv4.2.
In NFS version 4.1 and 4.2, callback operations may appear on the In NFS version 4.1 and 4.2, callback operations may appear on the
same connection as one used for NFS version 4 client requests. To same connection as one used for NFS version 4 client requests. NFS
operate on RPC-over-RDMA transports, NFS version 4 clients and version 4 clients and servers MUST use the mechanism described in
servers MUST use the mechanism described in [I-D.ietf-nfsv4-rpcrdma-bidirection] when backchannel operations are
[I-D.ietf-nfsv4-rpcrdma-bidirection]. conveyed on RPC-over-RDMA transports.
5. IANA Considerations 5. IANA 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 that 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
 End of changes. 37 change blocks. 
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