Network File System (NFS) Upper Layer Binding To RPC-Over-RDMA Version 2
draft-ietf-nfsv4-nfs-ulb-v2-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Expired".
|
|
|---|---|---|---|
| Author | Chuck Lever | ||
| Last updated | 2019-11-17 | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Formats | |||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | WG Document | |
| Document shepherd | (None) | ||
| IESG | IESG state | I-D Exists | |
| Consensus boilerplate | Unknown | ||
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-ietf-nfsv4-nfs-ulb-v2-00
Network File System Version 4 C. Lever
Internet-Draft Oracle
Intended status: Standards Track November 17, 2019
Expires: May 20, 2020
Network File System (NFS) Upper Layer Binding To RPC-Over-RDMA Version 2
draft-ietf-nfsv4-nfs-ulb-v2-00
Abstract
This document specifies Upper Layer Bindings of Network File System
(NFS) protocol versions to RPC-over-RDMA version 2.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six 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."
This Internet-Draft will expire on May 20, 2020.
Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://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.
This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
Lever Expires May 20, 2020 [Page 1]
Internet-Draft NFS on RPC-Over-RDMA V2 November 2019
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Reply Size Estimation . . . . . . . . . . . . . . . . . . . . 3
4. Upper Layer Binding for NFS Versions 2 and 3 . . . . . . . . 3
4.1. Reply Size Estimation . . . . . . . . . . . . . . . . . . 4
4.2. RPC Binding Considerations . . . . . . . . . . . . . . . 4
5. Upper Layer Bindings for NFS Version 2 and 3 Auxiliary
Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5.1. MOUNT, NLM, and NSM Protocols . . . . . . . . . . . . . . 5
5.2. NFSACL Protocol . . . . . . . . . . . . . . . . . . . . . 5
6. Upper Layer Binding For NFS Version 4 . . . . . . . . . . . . 5
6.1. DDP-Eligibility . . . . . . . . . . . . . . . . . . . . . 5
6.2. Reply Size Estimation . . . . . . . . . . . . . . . . . . 6
6.3. RPC Binding Considerations . . . . . . . . . . . . . . . 7
6.4. NFS COMPOUND Requests . . . . . . . . . . . . . . . . . . 7
6.5. NFS Callback Requests . . . . . . . . . . . . . . . . . . 9
6.6. Session-Related Considerations . . . . . . . . . . . . . 10
6.7. Transport Considerations . . . . . . . . . . . . . . . . 11
7. Extending NFS Upper Layer Bindings . . . . . . . . . . . . . 13
8. Security Considerations . . . . . . . . . . . . . . . . . . . 13
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
10.1. Normative References . . . . . . . . . . . . . . . . . . 14
10.2. Informative References . . . . . . . . . . . . . . . . . 15
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 15
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction
The RPC-over-RDMA version 2 transport may employ direct data
placement to convey data payloads associated with RPC transactions
[I-D.cel-nfsv4-rpcrdma-version-two]. To enable successful
interoperation, RPC client and server implementations using RPC-over-
RDMA version 2 must agree which XDR data items and RPC procedures are
eligible to use direct data placement (DDP).
Lever Expires May 20, 2020 [Page 2]
Internet-Draft NFS on RPC-Over-RDMA V2 November 2019
An Upper Layer Binding specifies this agreement for one or more
versions of one RPC program. Other operational details, such as RPC
binding assignments, pairing Write chunks with result data items, and
reply size estimation, are also specified by this Binding.
This document contains material required of Upper Layer Bindings, as
specified in [I-D.cel-nfsv4-rpcrdma-version-two], for the following
NFS protocol versions:
o NFS version 2 [RFC1094]
o NFS version 3 [RFC1813]
o NFS version 4.0 [RFC7530]
o NFS version 4.1 [RFC5661]
o NFS version 4.2 [RFC7862]
Upper Layer Bindings are also provided for auxiliary protocols used
with NFS versions 2 and 3 (see Section 5).
This document assumes the reader is already familiar with concepts
and terminology defined in [I-D.cel-nfsv4-rpcrdma-version-two] and
the documents it references.
2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Reply Size Estimation
During the construction of each RPC Call message, a Requester is
responsible for allocating appropriate resources for receiving the
corresponding Reply message. If the Requester expects the RPC Reply
message will be larger than its inline threshold, it MAY provide
Write and/or Reply chunks wherein the Responder can place results and
the reply's Payload stream.
4. Upper Layer Binding for NFS Versions 2 and 3
The Upper Layer Binding specification in this section applies to NFS
version 2 [RFC1094] and NFS version 3 [RFC1813]. For brevity, in
this document a "Legacy NFS client" refers to an NFS client using
Lever Expires May 20, 2020 [Page 3]
Internet-Draft NFS on RPC-Over-RDMA V2 November 2019
version 2 or version 3 of the NFS RPC program (100003) to communicate
with an NFS server. Likewise, a "Legacy NFS server" is an NFS server
communicating with clients using NFS version 2 or NFS version 3.
The following XDR data items in NFS versions 2 and 3 are DDP-
eligible:
o The opaque file data argument in the NFS WRITE procedure
o The pathname argument in the NFS SYMLINK procedure
o The opaque file data result in the NFS READ procedure
o The pathname result in the NFS READLINK procedure
All other argument or result data items in NFS versions 2 and 3 are
not DDP-eligible.
A transport error does not give an indication of whether the server
has processed the arguments of the RPC Call, or whether the server
has accessed or modified client memory associated with that RPC.
4.1. Reply Size Estimation
A Legacy NFS client determines the maximum reply size for each
operation using the criteria outlined in Section 3.
4.2. RPC Binding Considerations
Legacy NFS servers traditionally listen for clients on UDP and TCP
port 2049. Additionally, they register these ports with a local
portmapper service [RFC1833].
A Legacy NFS server supporting RPC-over-RDMA version 2 on such a
network and registering itself with the RPC portmapper MAY choose an
arbitrary port, or MAY use the alternative well-known port number for
its RPC-over-RDMA service (see Section 9). The chosen port MAY be
registered with the RPC portmapper using the netids assigned in
[I-D.cel-nfsv4-rpcrdma-version-two].
5. Upper Layer Bindings for NFS Version 2 and 3 Auxiliary Protocols
NFS versions 2 and 3 are typically deployed with several other
protocols, sometimes referred to as "NFS auxiliary protocols." These
are distinct RPC programs that define procedures which are not part
of the NFS RPC program (100003). The Upper Layer Bindings in this
section apply to:
Lever Expires May 20, 2020 [Page 4]
Internet-Draft NFS on RPC-Over-RDMA V2 November 2019
o Versions 2 and 3 of the MOUNT RPC program (100005) [RFC1813]
o Versions 1, 3, and 4 of the NLM RPC program (100021) [RFC1813]
o Version 1 of the NSM RPC program (100024), described in Chapter 11
of [XNFS]
o Version 1 of the NFSACL RPC program (100227), which does not have
a public definition. NFSACL is treated in this document as a de
facto standard, as there are several interoperating
implementations.
5.1. MOUNT, NLM, and NSM Protocols
Historically, NFS/RDMA implementations have chosen to convey the
MOUNT, NLM, and NSM protocols via TCP. To enable interoperation of
these protocols when NFS/RDMA is in use, a legacy NFS server MUST
provide support for these protocols via TCP.
5.2. NFSACL Protocol
Legacy clients and servers that support the NFSACL RPC program
typically convey NFSACL procedures on the same connection as the NFS
RPC program (100003). This obviates the need for separate rpcbind
queries to discover server support for this RPC program.
ACLs are typically small, but even large ACLs must be encoded and
decoded to some degree. Thus no data item in this Upper Layer
Protocol is DDP-eligible.
For procedures whose replies do not include an ACL object, the size
of a reply is determined directly from the NFSACL RPC program's XDR
definition. Legacy client implementations should choose a maximum
size for ACLs based on their own internal limits.
6. Upper Layer Binding For NFS Version 4
The Upper Layer Binding specification in this section applies to
versions of the NFS RPC program defined in NFS version 4.0 [RFC7530]
NFS version 4.1 [RFC5661] and NFS version 4.2 [RFC7862]
6.1. DDP-Eligibility
Only the following XDR data items in the COMPOUND procedure of all
NFS version 4 minor versions are DDP-eligible:
o The opaque data field in the WRITE4args structure
Lever Expires May 20, 2020 [Page 5]
Internet-Draft NFS on RPC-Over-RDMA V2 November 2019
o The linkdata field of the NF4LNK arm in the createtype4 union
o The opaque data field in the READ4resok structure
o The linkdata field in the READLINK4resok structure
6.2. Reply Size Estimation
Within NFS version 4, there are certain variable-length result data
items whose maximum size cannot be estimated by clients reliably
because there is no protocol-specified size limit on these result
arrays. These include:
o The attrlist4 field
o Fields containing ACLs such as fattr4_acl, fattr4_dacl, and
fattr4_sacl
o Fields in the fs_locations4 and fs_locations_info4 data structures
o Fields opaque to the NFS version 4 protocol which pertain to pNFS
layout metadata, such as loc_body, loh_body, da_addr_body,
lou_body, lrf_body, fattr_layout_types, and fs_layout_types
6.2.1. Reply Size Estimation for Minor Version 0
The NFS version 4.0 protocol itself does not impose any bound on the
size of NFS calls or responses.
Some of the data items enumerated in Section 6.2 (in particular, the
items related to ACLs and fs_locations) make it difficult to predict
the maximum size of NFS version 4.0 replies that interrogate
variable-length fattr4 attributes. Client implementations might rely
on their own internal architectural limits to constrain the reply
size, but such limits are not always guaranteed to be reliable.
When an especially large fattr4 result is expected, an NFS version
4.0 client can provide a Reply chunk to enable a large result to be
returned via explicit RDMA. An NFS version 4.0 client can use short
Reply chunk retry when an NFS COMPOUND containing a GETATTR operation
encounters a transport error.
6.2.2. Reply Size Estimation for Minor Version 1 and Newer
In NFS version 4.1 and newer minor versions, the csa_fore_chan_attrs
argument of the CREATE_SESSION operation contains a
ca_maxresponsesize field. The value in this field can be taken as
Lever Expires May 20, 2020 [Page 6]
Internet-Draft NFS on RPC-Over-RDMA V2 November 2019
the absolute maximum size of replies generated by an NFS version 4.1
server.
This value can be used in cases where it is not possible to estimate
a reply size upper bound precisely. In practice, objects such as
ACLs, named attributes, layout bodies, and security labels are much
smaller than this maximum.
6.3. RPC Binding Considerations
NFS version 4 servers are required to listen on TCP port 2049, and
they are not required to register with an rpcbind service [RFC7530]
Therefore, an NFS version 4 server supporting RPC-over-RDMA version 2
MUST use the alternative well-known port number for its RPC-over-RDMA
service (see Section 9 Clients SHOULD connect to this well-known port
without consulting the RPC portmapper (as for NFS version 4 on TCP
transports).
6.4. NFS COMPOUND Requests
6.4.1. Multiple DDP-eligible Data Items
An NFS version 4 COMPOUND procedure can contain more than one
operation that carries a DDP-eligible data item. An NFS version 4
client provides XDR Position values in each Read chunk to
disambiguate which chunk is associated with which argument data item.
However NFS version 4 server and client implementations must agree in
advance on how to pair Write chunks with returned result data items.
In the following list, a "READ operation" refers to any NFS version 4
operation which has a DDP-eligible result data item. The mechanism
specified in Section 4.3.2 of [I-D.cel-nfsv4-rpcrdma-version-two] is
applied to this class of operations:
o If an NFS version 4 client wishes all DDP-eligible items in an NFS
reply to be conveyed inline, it leaves the Write list empty.
o The first chunk in the Write list MUST be used by the first READ
operation in an NFS version 4 COMPOUND procedure. The next Write
chunk is used by the next READ operation, and so on.
o If an NFS version 4 client has provided a matching non-empty Write
chunk, then the corresponding READ operation MUST return its DDP-
eligible data item using that chunk.
Lever Expires May 20, 2020 [Page 7]
Internet-Draft NFS on RPC-Over-RDMA V2 November 2019
o If an NFS version 4 client has provided an empty matching Write
chunk, then the corresponding READ operation MUST return all of
its result data items inline.
o If a READ operation returns a union arm which does not contain a
DDP-eligible result, and the NFS version 4 client has provided a
matching non-empty Write chunk, an NFS version 4 server MUST
return an empty Write chunk in that Write list position.
o If there are more READ operations than Write chunks, then
remaining NFS Read operations in an NFS version 4 COMPOUND that
have no matching Write chunk MUST return their results inline.
6.4.2. Chunk List Complexity
The RPC-over-RDMA version 2 protocol does not place any limit on the
number of chunks or segments that may appear in Read or Write lists.
However, for various reasons NFS version 4 server implementations
often have practical limits on the number of chunks or segments they
are prepared to process in a single RPC transaction conveyed via RPC-
over-RDMA version 2.
These implementation limits are especially important when Kerberos
integrity or privacy is in use [RFC7861]. GSS services increase the
size of credential material in RPC headers, potentially requiring the
use of Long messages. This can increase the complexity of chunk
lists independent of the NFS version 4 COMPOUND being conveyed.
In the absence of explicit knowledge of the server's limits, NFS
version 4 clients SHOULD follow the prescriptions listed below when
constructing RPC-over-RDMA version 2 messages. NFS version 4 servers
MUST accept and process such requests.
o The Read list can contain either a Position-Zero Read chunk, one
Read chunk with a non-zero Position, or both.
o The Write list can contain no more than one Write chunk.
o Any chunk can contain up to sixteen RDMA segments.
NFS version 4 clients wishing to send more complex chunk lists can
provide configuration interfaces to bound the complexity of NFS
version 4 COMPOUNDs, limit the number of elements in scatter-gather
operations, and avoid other sources of chunk overruns at the
receiving peer.
An NFS version 4 server SHOULD return one of the following responses
to a client that has sent an RPC transaction via RPC-over-RDMA
Lever Expires May 20, 2020 [Page 8]
Internet-Draft NFS on RPC-Over-RDMA V2 November 2019
version 2 which cannot be processed due to chunk list complexity
limits on the server:
o A problem is detected by the transport layer while parsing the
transport header in an RPC Call message. The server responds with
an RDMA2_ERROR message with the err field set to ERR_CHUNK.
o A problem is detected during XDR decoding of the RPC Call message
while the RPC layer reassembles the call's XDR stream. The server
responds with an RPC reply with its "reply_stat" field set to
MSG_ACCEPTED and its "accept_stat" field set to GARBAGE_ARGS.
After receiving one of these errors, an NFS version 4 client SHOULD
NOT retransmit the failing request, as the result would be the same
error. It SHOULD immediately terminate the RPC transaction
associated with the XID in the reply.
6.4.3. NFS Version 4 COMPOUND Example
The following example shows a Write list with three Write chunks, A,
B, and C. The NFS version 4 server consumes the provided Write
chunks by writing the results of the designated operations in the
compound request (READ and READLINK) back to each chunk.
Write list:
A --> B --> C
NFS version 4 COMPOUND request:
PUTFH LOOKUP READ PUTFH LOOKUP READLINK PUTFH LOOKUP READ
| | |
v v v
A B C
If the NFS version 4 client does not want to have the READLINK result
returned via RDMA, it provides an empty Write chunk for buffer B to
indicate that the READLINK result must be returned inline.
6.5. NFS Callback Requests
The NFS version 4 family of protocols support server-initiated
callbacks to notify NFS version 4 clients of events such as recalled
delegations.
Lever Expires May 20, 2020 [Page 9]
Internet-Draft NFS on RPC-Over-RDMA V2 November 2019
6.5.1. NFS Version 4.0 Callback
NFS version 4.0 implementations typically employ a separate TCP
connection to handle callback operations, even when the forward
channel uses an RPC-over-RDMA version 2 transport.
No operation in the NFS version 4.0 callback RPC program conveys a
data payload of significant size. Therefore, no XDR data items in
this RPC program is DDP-eligible.
A CB_RECALL reply is small and fixed in size. The CB_GETATTR reply
contains a variable-length fattr4 data item. See Section 6.2.1 for a
discussion of reply size prediction for this data item.
An NFS version 4.0 client advertises netids and ad hoc port addresses
for contacting its NFS version 4.0 callback service using the
SETCLIENTID operation.
6.5.2. NFS Version 4.1 Callback
In NFS version 4.1 and newer minor versions, callback operations may
appear on the same connection as is used for NFS version 4 forward
channel client requests. NFS version 4 clients and servers MUST use
the approach described in [RFC8167] when backchannel operations are
conveyed on RPC-over-RDMA version 2 transports.
The csa_back_chan_attrs argument of the CREATE_SESSION operation
contains a ca_maxresponsesize field. The value in this field can be
taken as the absolute maximum size of backchannel replies generated
by a replying NFS version 4 client.
There are no DDP-eligible data items in callback procedures defined
in NFS version 4.1 or NFS version 4.2. However, some callback
operations, such as messages that convey device ID information, can
be large. Message Continuation or a Long message might be used in
this situation.
When an NFS version 4.1 client can support Long Calls in its
backchannel, it reports a backchannel ca_maxrequestsize that is
larger than the connection's inline thresholds. Otherwise an NFS
version 4 server MUST use only Short messages to convey backchannel
operations.
6.6. Session-Related Considerations
The presence of an NFS session (defined in [RFC5661] has no effect on
the operation of RPC-over-RDMA version 2. None of the operations
introduced to support NFS sessions (e.g. the SEQUENCE operation)
Lever Expires May 20, 2020 [Page 10]
Internet-Draft NFS on RPC-Over-RDMA V2 November 2019
contain DDP-eligible data items. There is no need to match the
number of session slots with the number of available RPC-over-RDMA
version 2 credits.
However, there are a few new cases where an RPC transaction can fail.
For example, a Requester might receive, in response to an RPC
request, an RDMA2_ERROR message with an rdma_err value of ERR_CHUNK.
These situations are not different from existing RPC errors which an
NFS session implementation is already prepared to handle for other
transports. And as with other transports during such a failure,
there might be no SEQUENCE result available to the Requester to
distinguish whether failure occurred before or after the requested
operations were executed on the Responder.
When a transport error occurs (e.g. RDMA2_ERROR), the Requester
proceeds as usual to match the incoming XID value to a waiting RPC
Call. The RPC transaction is terminated, and the result status is
reported to the Upper Layer Protocol. The Requester's session
implementation then determines the session ID and slot for the failed
request, and performs slot recovery to make that slot usable again.
If this were not done, that slot could be rendered permanently
unavailable.
When an NFS session is not present (for example, when NFS version 4.0
is in use), a transport error does not provide an indication of
whether the server has processed the arguments of the RPC Call, or
whether the server has accessed or modified client memory associated
with that RPC.
6.7. Transport Considerations
6.7.1. Congestion Avoidance
Section 3.1 of [RFC7530] states:
Where an NFS version 4 implementation supports operation over the
IP network protocol, the supported transport layer between NFS and
IP MUST be an IETF standardized transport protocol that is
specified to avoid network congestion; such transports include TCP
and the Stream Control Transmission Protocol (SCTP).
Section 2.9.1 of [RFC5661] further states:
Even if NFS version 4.1 is used over a non-IP network protocol, it
is RECOMMENDED that the transport support congestion control.
It is permissible for a connectionless transport to be used under
NFS version 4.1; however, reliable and in-order delivery of data
Lever Expires May 20, 2020 [Page 11]
Internet-Draft NFS on RPC-Over-RDMA V2 November 2019
combined with congestion control by the connectionless transport
is REQUIRED. As a consequence, UDP by itself MUST NOT be used as
an NFS version 4.1 transport.
RPC-over-RDMA version 2 is constructed on a platform of RDMA Reliable
Connected QP type connections [I-D.cel-nfsv4-rpcrdma-version-two]
[RFC5041]. RDMA Reliable Connected QPs are reliable, connection-
oriented transports that guarantee in-order delivery, meeting all
above requirements for NFS version 4 transports.
6.7.2. Retransmission and Keep-alive
NFS version 4 client implementations often rely on a transport-layer
keep-alive mechanism to detect when an NFS version 4 server has
become unresponsive. When an NFS server is no longer responsive,
client-side keep-alive terminates the connection, which in turn
triggers reconnection and RPC retransmission.
Some RDMA transports (such as the Reliable Connected QP type on
InfiniBand) have no keep-alive mechanism. Without a disconnect or
new RPC traffic, such connections can remain alive long after an NFS
server has become unresponsive. Once an NFS client has consumed all
available RPC-over-RDMA version 2 credits on that transport
connection, it will forever await a reply before sending another RPC
request.
NFS version 4 clients SHOULD reserve one RPC-over-RDMA version 2
credit to use for periodic server or connection health assessment.
This credit can be used to drive an RPC request on an otherwise idle
connection, triggering either a quick affirmative server response or
immediate connection termination.
In addition to network partition and request loss scenarios, RPC-
over-RDMA version 2 transport connections can be terminated when a
Transport header is malformed, Reply messages are larger than receive
resources, or when too many RPC-over-RDMA messages are sent at once.
In such cases:
o If there is a transport error indicated (ie, RDMA2_ERROR) before
the disconnect or instead of a disconnect, the Requester MUST
respond to that error as prescribed by the specification of the
RPC transport. Then the NFS version 4 rules for handling
retransmission apply.
o If there is a transport disconnect and the Responder has provided
no other response for a request, then only the NFS version 4 rules
for handling retransmission apply.
Lever Expires May 20, 2020 [Page 12]
Internet-Draft NFS on RPC-Over-RDMA V2 November 2019
7. Extending NFS Upper Layer Bindings
RPC programs such as NFS are required to have an Upper Layer Binding
specification to interoperate on RPC-over-RDMA version 2 transports
[I-D.cel-nfsv4-rpcrdma-version-two]. Via standards action, 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, or to cover separately published extensions to an
existing NFS version 4 minor version, as described in [RFC8178].
8. Security Considerations
RPC-over-RDMA version 2 supports all RPC security models, including
RPCSEC_GSS security and transport-level security [RFC7861]. The
choice of what Direct Data Placement mechanism to convey RPC argument
and results does not affect this, since it changes only the method of
data transfer. Because the current document defines only the binding
of the NFS protocols atop [I-D.cel-nfsv4-rpcrdma-version-two], all
relevant security considerations are therefore to be described at
that layer.
9. IANA Considerations
The use of direct data placement in NFS introduces a need for an
additional port number assignment for networks that share traditional
UDP and TCP port spaces with RDMA services. The iWARP protocol is
such an example [RFC5040] [RFC5041].
For this purpose, a set of transport protocol port number assignments
is specified by this document. IANA has assigned the following ports
for NFS/RDMA in the IANA port registry, according to the guidelines
described in [RFC6335].
nfsrdma 20049/tcp Network File System (NFS) over RDMA
nfsrdma 20049/udp Network File System (NFS) over RDMA
nfsrdma 20049/sctp Network File System (NFS) over RDMA
This document should be listed as a reference for the nfsrdma port
assignments. This document does not alter these assignments.
10. References
Lever Expires May 20, 2020 [Page 13]
Internet-Draft NFS on RPC-Over-RDMA V2 November 2019
10.1. Normative References
[I-D.cel-nfsv4-rpcrdma-version-two]
Lever, C. and D. Noveck, "RPC-over-RDMA Version 2
Protocol", draft-cel-nfsv4-rpcrdma-version-two-09 (work in
progress), May 2019.
[RFC1833] Srinivasan, R., "Binding Protocols for ONC RPC Version 2",
RFC 1833, DOI 10.17487/RFC1833, August 1995,
<https://www.rfc-editor.org/info/rfc1833>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC5661] Shepler, S., Ed., Eisler, M., Ed., and D. Noveck, Ed.,
"Network File System (NFS) Version 4 Minor Version 1
Protocol", RFC 5661, DOI 10.17487/RFC5661, January 2010,
<https://www.rfc-editor.org/info/rfc5661>.
[RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S.
Cheshire, "Internet Assigned Numbers Authority (IANA)
Procedures for the Management of the Service Name and
Transport Protocol Port Number Registry", BCP 165,
RFC 6335, DOI 10.17487/RFC6335, August 2011,
<https://www.rfc-editor.org/info/rfc6335>.
[RFC7530] Haynes, T., Ed. and D. Noveck, Ed., "Network File System
(NFS) Version 4 Protocol", RFC 7530, DOI 10.17487/RFC7530,
March 2015, <https://www.rfc-editor.org/info/rfc7530>.
[RFC7861] Adamson, A. and N. Williams, "Remote Procedure Call (RPC)
Security Version 3", RFC 7861, DOI 10.17487/RFC7861,
November 2016, <https://www.rfc-editor.org/info/rfc7861>.
[RFC7862] Haynes, T., "Network File System (NFS) Version 4 Minor
Version 2 Protocol", RFC 7862, DOI 10.17487/RFC7862,
November 2016, <https://www.rfc-editor.org/info/rfc7862>.
[RFC8167] Lever, C., "Bidirectional Remote Procedure Call on RPC-
over-RDMA Transports", RFC 8167, DOI 10.17487/RFC8167,
June 2017, <https://www.rfc-editor.org/info/rfc8167>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
Lever Expires May 20, 2020 [Page 14]
Internet-Draft NFS on RPC-Over-RDMA V2 November 2019
10.2. Informative References
[RFC1094] Nowicki, B., "NFS: Network File System Protocol
specification", RFC 1094, DOI 10.17487/RFC1094, March
1989, <https://www.rfc-editor.org/info/rfc1094>.
[RFC1813] Callaghan, B., Pawlowski, B., and P. Staubach, "NFS
Version 3 Protocol Specification", RFC 1813,
DOI 10.17487/RFC1813, June 1995,
<https://www.rfc-editor.org/info/rfc1813>.
[RFC5040] Recio, R., Metzler, B., Culley, P., Hilland, J., and D.
Garcia, "A Remote Direct Memory Access Protocol
Specification", RFC 5040, DOI 10.17487/RFC5040, October
2007, <https://www.rfc-editor.org/info/rfc5040>.
[RFC5041] Shah, H., Pinkerton, J., Recio, R., and P. Culley, "Direct
Data Placement over Reliable Transports", RFC 5041,
DOI 10.17487/RFC5041, October 2007,
<https://www.rfc-editor.org/info/rfc5041>.
[RFC8178] Noveck, D., "Rules for NFSv4 Extensions and Minor
Versions", RFC 8178, DOI 10.17487/RFC8178, July 2017,
<https://www.rfc-editor.org/info/rfc8178>.
[XNFS] The Open Group, "Protocols for Interworking: XNFS, Version
3W", February 1998.
Acknowledgments
Thanks to Tom Talpey, who contributed the text of Section 6.4.2.
Dave Noveck contributed the text of Section 6.6 and Section 7.
Special thanks go to Transport Area Director Magnus Westerlund, NFSV4
Working Group Chairs Spencer Shepler and Brian Pawlowski, and NFSV4
Working Group Secretary Thomas Haynes for their support. The author
also wishes to thank Bill Baker and Greg Marsden for their support of
this work.
Author's Address
Charles Lever
Oracle Corporation
United States of America
Email: chuck.lever@oracle.com
Lever Expires May 20, 2020 [Page 15]