Remote Direct Memory Access - Connection Manager (RDMA-CM) Private Data for RPC-over-RDMA Version 1
draft-ietf-nfsv4-rpcrdma-cm-pvt-data-08

Network File System Version 4                                   C. Lever
Internet-Draft                                                    Oracle
Updates: 8166 (if approved)                            February 21, 2020
Intended status: Standards Track
Expires: August 24, 2020

    RDMA Connection Manager Private Data For RPC-Over-RDMA Version 1
                draft-ietf-nfsv4-rpcrdma-cm-pvt-data-08

Abstract

   This document specifies the format of Remote Direct Memory Access -
   Connection Manager (RDMA-CM) Private Data exchanged between RPC-over-
   RDMA version 1 peers as part of establishing a connection.  The
   addition of the private data payload specified in this document is an
   optional extension that does not alter the RPC-over-RDMA version 1
   protocol.  This document updates RFC 8166.

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
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   This Internet-Draft will expire on August 24, 2020.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   include Simplified BSD License text as described in Section 4.e of

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  Advertised Transport Properties . . . . . . . . . . . . . . .   3
     3.1.  Inline Threshold Size . . . . . . . . . . . . . . . . . .   4
     3.2.  Remote Invalidation . . . . . . . . . . . . . . . . . . .   4
   4.  Private Data Message Format . . . . . . . . . . . . . . . . .   5
     4.1.  Using the R Field . . . . . . . . . . . . . . . . . . . .   7
     4.2.  Send and Receive Size Values  . . . . . . . . . . . . . .   7
   5.  Interoperability Considerations . . . . . . . . . . . . . . .   7
     5.1.  Interoperability with RPC-over-RDMA Version 1
           Implementations . . . . . . . . . . . . . . . . . . . . .   8
     5.2.  Interoperability Amongst RDMA Transports  . . . . . . . .   8
   6.  Updating the Message Format . . . . . . . . . . . . . . . . .   8
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
     8.1.  Guidance for Designated Experts . . . . . . . . . . . . .  10
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  12
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  12
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  13

1.  Introduction

   The RPC-over-RDMA version 1 transport protocol [RFC8166] enables
   payload data transfer using Remote Direct Memory Access (RDMA) for
   upper-layer protocols based on Remote Procedure Calls (RPC)
   [RFC5531].  The terms "Remote Direct Memory Access" (RDMA) and
   "Direct Data Placement" (DDP) are introduced in [RFC5040].

   The two most immediate shortcomings of RPC-over-RDMA version 1 are:

   o  Setting up an RDMA data transfer (via RDMA Read or Write) can be
      costly.  The small default size of messages transmitted using RDMA
      Send forces the use of RDMA Read or Write operations even for
      relatively small messages and data payloads.
      The original specification of RPC-over-RDMA version 1 provided an
      out-of-band protocol for passing inline threshold values between
      connected peers [RFC5666].  However, [RFC8166] eliminated support
      for this protocol making it unavailable for this purpose.

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   o  Unlike most other contemporary RDMA-enabled storage protocols,
      there is no facility in RPC-over-RDMA version 1 that enables the
      use of remote invalidation [RFC5042].

   Each RPC-over-RDMA version 1 transport header follows the External
   Data Representation (XDR) [RFC4506] definition specified in
   [RFC8166].  However, RPC-over-RDMA version 1 has no means of
   extending this definition in such a way that interoperability with
   existing implementations is preserved.  As a result, an out-of-band
   mechanism is needed to help relieve these constraints for existing
   RPC-over-RDMA version 1 implementations.

   This document specifies a simple, non-XDR-based message format
   designed to be passed between RPC-over-RDMA version 1 peers at the
   time each RDMA transport connection is first established.  The
   mechanism assumes that the underlying RDMA transport has a private
   data field that is passed between peers at connection time, such as
   is present in the iWARP protocol (described in Section 7.1 of
   [RFC5044]) or the InfiniBand Connection Manager [IBA].

   To enable current RPC-over-RDMA version 1 implementations to
   interoperate with implementations that support the private message
   format described in this document, implementation of the private data
   message is OPTIONAL.  When the private data message has been
   successfully exchanged, peers may choose to perform extended RDMA
   semantics.  However, the private message format does not alter the
   XDR definition specified in [RFC8166].

   The message format is intended to be further extensible within the
   normal scope of such IETF work (see Section 6 for further details).
   Section 8 of this document defines an IANA registry for this purpose.
   In addition, interoperation between implementations of RPC-over-RDMA
   version 1 that present this message format to peers and those that do
   not recognize this message format is guaranteed.

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.  Advertised Transport Properties

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3.1.  Inline Threshold Size

   Section 3.3.2 of [RFC8166] defines the term "inline threshold."  An
   inline threshold is the maximum number of bytes that can be
   transmitted using one RDMA Send and one RDMA Receive.  There are a
   pair of inline thresholds for a connection: a client-to-server
   threshold and a server-to-client threshold.

   If an incoming RDMA message exceeds the size of a receiver's inline
   threshold, the receive operation fails and the RDMA provider
   typically terminates the connection.  To convey an RPC message larger
   than the receiver's inline threshold without risking receive failure,
   a sender must use explicit RDMA data transfer operations, which are
   more expensive than an RDMA Send.  See Sections 3.3 and 3.5 of
   [RFC8166] for a complete discussion.

   The default value of inline thresholds for RPC-over-RDMA version 1
   connections is 1024 bytes (as defined in Section 3.3.3 of [RFC8166]).
   This value is adequate for nearly all NFS version 3 procedures.

   NFS version 4 COMPOUND operations [RFC7530] are larger on average
   than NFS version 3 procedures [RFC1813], forcing clients to use
   explicit RDMA operations for frequently-issued requests such as
   LOOKUP and GETATTR.  The use of RPCSEC_GSS security also increases
   the average size of RPC messages, due to the larger size of
   RPCSEC_GSS credential material included in RPC headers [RFC7861].

   If a sender and receiver could somehow agree on larger inline
   thresholds, frequently-used RPC transactions avoid the cost of
   explicit RDMA operations.

3.2.  Remote Invalidation

   After an RDMA data transfer operation completes, an RDMA consumer can
   request that its peer's RDMA network interface card (RNIC) invalidate
   the Steering Tag (STag) associated with the data transfer [RFC5042].

   An RDMA consumer requests remote invalidation by posting an RDMA Send
   With Invalidate Work Request in place of an RDMA Send Work Request.
   Each RDMA Send With Invalidate carries one STag to invalidate.  The
   receiver of an RDMA Send With Invalidate performs the requested
   invalidation and then reports that invalidation as part of the
   completion of a waiting Receive Work Request.

   If both peers support remote invalidation, an RPC-over-RDMA responder
   might use remote invalidation when replying to an RPC request that
   provided chunks.  Because one of the chunks has already been

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   invalidated, finalizing the results of the RPC is made simpler and
   faster.

   However, there are some important caveats which contraindicate the
   blanket use of remote invalidation:

   o  Remote invalidation is not supported by all RNICs.

   o  Not all RPC-over-RDMA responder implementations can generate RDMA
      Send With Invalidate Work Requests.

   o  Not all RPC-over-RDMA requester implementations can recognize when
      remote invalidation has occurred.

   o  On one connection in different RPC-over-RDMA transactions, or in a
      single RPC-over-RDMA transaction, an RPC-over-RDMA requester can
      expose a mixture of STags that may be invalidated remotely and
      some that must not be.  No indication is provided at the RDMA
      layer as to which is which.

   A responder therefore must not employ remote invalidation unless it
   is aware of support for it in its own RDMA stack, and on the
   requester.  And, without altering the XDR structure of RPC-over-RDMA
   version 1 messages, it is not possible to support remote invalidation
   with requesters that mix STags that may and must not be invalidated
   remotely in a single RPC or on the same connection.

   There are some NFS/RDMA client implementations whose STags are always
   safe to invalidate remotely.  For such clients, indicating to the
   responder that remote invalidation is always safe can enable such
   invalidation without the need for additional protocol elements to be
   defined.

4.  Private Data Message Format

   With an InfiniBand lower layer, for example, RDMA connection setup
   uses a Connection Manager when establishing a Reliable Connection
   [IBA].  When an RPC-over-RDMA version 1 transport connection is
   established, the client (which actively establishes connections) and
   the server (which passively accepts connections) populate the CM
   Private Data field exchanged as part of CM connection establishment.

   The transport properties exchanged via this mechanism are fixed for
   the life of the connection.  Each new connection presents an
   opportunity for a fresh exchange.  An implementation of the extension
   described in this document MUST be prepared for the settings to
   change upon a reconnection.

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   For RPC-over-RDMA version 1, the CM Private Data field is formatted
   as described in the following subsection.  RPC clients and servers
   use the same format.  If the capacity of the Private Data field is
   too small to contain this message format or the underlying RDMA
   transport is not managed by a Connection Manager, the CM Private Data
   field cannot be used on behalf of RPC-over-RDMA version 1.

   The first 8 octets of the CM Private Data field is to be formatted as
   follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Format Identifier                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Version    |  Reserved   |R|   Send Size   | Receive Size  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Format Identifier:  This field contains a fixed 32-bit value that
      identifies the content of the Private Data field as an RPC-over-
      RDMA version 1 CM Private Data message.  In RPC-over-RDMA version
      1 Private Data, the value of this field is always 0xf6ab0e18, in
      network byte order.  The use of this field is further expanded
      upon in Section 5.2.

   Version:  This 8-bit field contains a message format version number.
      The value "1" in this field indicates that exactly eight octets
      are present, that they appear in the order described in this
      section, and that each has the meaning defined in this section.
      Further considerations about the use of this field are discussed
      in Section 6.

   Reserved:  This 7-bit field is unused.  Senders MUST set these bits
      to zero and receivers MUST ignore their value.

   R: This 1-bit field indicates that the sender supports remote
      invalidation.  The field is set and interpreted as described in
      Section 4.1.

   Send Size:  This 8-bit field contains an encoded value corresponding
      to the maximum number of bytes this peer is prepared to transmit
      in a single RDMA Send on this connection.  The value is encoded as
      described in Section 4.2.

   Receive Size:  This 8-bit field contains an encoded value
      corresponding to the maximum number of bytes this peer is prepared
      to receive with a single RDMA Receive on this connection.  The
      value is encoded as described in Section 4.2.

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4.1.  Using the R Field

   The R field indicates limited support for remote invalidate as
   described in Section 3.2.  When both connection peers have set this
   bit flag in their CM Private Data, the responder MAY use RDMA Send
   With Invalidate when transmitting RPC Replies.  Each RDMA Send With
   Invalidate MUST invalidate an STag associated only with the XID in
   the rdma_xid field of the RPC-over-RDMA Transport Header it carries.

   When either peer on a connection clears this flag, the responder MUST
   use only RDMA Send when transmitting RPC Replies.

4.2.  Send and Receive Size Values

   Inline threshold sizes from 1024 to 262144 octets can be represented
   in the Send Size and Receive Size fields.  The inline threshold
   values provide a pair of 1024-octet-aligned maximum message lengths
   that guarantee Send and Receive operations do not fail due to length
   errors.

   The minimum inline threshold for RPC-over-RDMA version 1 is 1024
   octets (see Section 3.3.3 of [RFC8166]).  The values in the Send Size
   and Receive Size fields represent the unsigned number of additional
   kilo-octets of length beyond the first 1024 octets.  Thus, a sender
   computes the encoded value by dividing its actual buffer size, in
   octets, by 1024 and subtracting one from the result.  A receiver
   decodes an incoming Size value by performing the inverse set of
   operations: it adds one to the encoded value and then multiplies that
   result by 1024.

   The client uses the smaller of its own send size and the server's
   reported receive size as the client-to-server inline threshold.  The
   server uses the smaller of its own send size and the clients's
   reported receive size as the server-to-client inline threshold.

5.  Interoperability Considerations

   The extension described in this document is designed to allow RPC-
   over-RDMA version implementations that use CM Private Data to
   interoperate fully with RPC-over-RDMA version 1 implementations that
   do not exchange this information.  Implementations that use this
   extension must also interoperate fully with RDMA implementations that
   use CM Private Data for other purposes.  Realizing these goals
   requires that implementations of this extension follow the practices
   described in the rest of this section.

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5.1.  Interoperability with RPC-over-RDMA Version 1 Implementations

   When a peer does not receive a CM Private Data message which conforms
   to Section 4, it needs to act as if the remote peer supports only the
   default RPC-over-RDMA version 1 settings, as defined in [RFC8166].
   In other words, the peer MUST behave as if a Private Data message was
   received in which bit 15 of the Flags field is zero, and both Size
   fields contain the value zero.

5.2.  Interoperability Amongst RDMA Transports

   The Format Identifier field defined in Section 4 is provided to
   enable implementations to distinguish RPC-over-RDMA version 1 Private
   Data from private data inserted at other layers, such as the private
   data inserted by the iWARP MPAv2 enhancement described in [RFC6581].

   As part of connection establishment, the received private data buffer
   is searched for the Format Identifier word.  The offset of the Format
   Identifier is not restricted to any alignment.  If the RPC-over-RDMA
   version 1 CM Private Data Format Identifier is not present, an RPC-
   over-RDMA version 1 receiver MUST behave as if no RPC-over-RDMA
   version 1 CM Private Data has been provided.

   Once the RPC-over-RDMA version 1 CM Private Data Format Identifier is
   found, the receiver parses the subsequent octets as RPC-over-RDMA
   version 1 CM Private Data.  As additional assurance that the private
   data content is valid RPC-over-RDMA version 1 CM Private Data, the
   receiver should check that the format version number field contains a
   valid and recognized version number and the size of the private data
   does not overrun the length of the buffer.

6.  Updating the Message Format

   Although the message format described in this document provides the
   ability for the client and server to exchange particular information
   about the local RPC-over-RDMA implementation, it is possible that
   there will be a future need to exchange additional properties.  This
   would make it necessary to extend or otherwise modify the format
   described in this document.

   Any modification faces the problem of interoperating properly with
   implementations of RPC-over-RDMA version 1 that are unaware of the
   existence of the new format.  These include implementations that that
   do not recognize the exchange of CM Private Data as well as those
   that recognize only the format described in this document.

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   Given the message format described in this document, these
   interoperability constraints could be met by the following sorts of
   new message formats:

   o  A format which uses a different value for the first four bytes of
      the format, as provided for in the registry described in
      Section 8.

   o  A format which uses the same value for the Format Identifier field
      and a value other than one (1) in the Version field.

   Although it is possible to reorganize the last three of the eight
   bytes in the existing format, extended formats are unlikely to do so.
   New formats would take the form of extensions of the format described
   in this document with added fields starting at byte eight of the
   format or changes to the definition of bits in the Reserved field.

7.  Security Considerations

   The reader is directed to the Security Considerations section of
   [RFC8166] for background and further discussion.

   The RPC-over-RDMA version 1 protocol framework depends on the
   semantics of the Reliable Connected (RC) queue pair (QP) type, as
   defined in Section 9.7.7 of [IBA].  The integrity of CM Private Data
   and the authenticity of its source are ensured by the exclusive use
   of RC queue pairs.  Any attempt to interfere with or hijack data in
   transit on an RC connection results in the RDMA provider terminating
   the connection.

   The Security Considerations section of [RFC5042] refers the reader to
   further relevant discussion of generic RDMA transport security.  That
   document recommends IPsec as the default transport layer security
   solution.  When deployed with iWARP, IPsec establishes a protected
   channel before any iWARP operations are exchanged, thus it protects
   the exchange of Private Data that occurs as each QP is established.
   However, IPsec is not available for InfiniBand or RoCE deployments.
   Those fabrics rely on physical security and cyclic redundancy checks
   to protect network traffic.

   Exchanging the information contained in the Private Message format
   defined in this document does not expose upper-layer payloads to an
   attacker.  Furthermore, the behavior changes that occur as a result
   of processing the CM Private Data format described in the current
   document do not introduce any new risk of exposure of upper-layer
   payload data.

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   Improperly setting one of the fields in a version 1 Private Message
   can result in an increased risk of disconnection (i.e., self-imposed
   Denial of Service).  A similar risk can arise if non-RPC-over-RDMA CM
   Private Data inadvertently contains the Format Identifier that
   identifies this protocol's data structure.  Additional checking of
   incoming Private Data, as described in Section 5.2, can help reduce
   this risk.

   In addition to describing the structure of a new format version, any
   document that extends the Private Data format described in the
   current document must discuss security considerations of new data
   items exchanged between connection peers.  Such documents should also
   explore the risks of erroneously identifying non-RPC-over-RDMA CM
   Private Data as the new format.

8.  IANA Considerations

   In accordance with [RFC8126], the author requests that IANA create a
   new registry in the "Remote Direct Data Placement" Protocol Category
   Group.  The new registry is to be called the "RDMA-CM Private Data
   Identifier Registry".  This is a registry of 32-bit numbers that
   identify the upper-layer protocol associated with data that appears
   in the application-specific RDMA-CM Private Data area.  The fields in
   this registry include: Format Identifier, Format Length (in octets),
   Description, and Reference.

   The initial contents of this registry are a single entry:

   +---------------+--------+------------------------------+-----------+
   | Format        | Length | Description                  | Reference |
   | Identifier    |        |                              |           |
   +---------------+--------+------------------------------+-----------+
   | 0xf6ab0e18    | 8      | RPC-over-RDMA version 1 CM   | [RFC-TBD] |
   |               |        | Private Data                 |           |
   +---------------+--------+------------------------------+-----------+

             Table 1: RDMA-CM Private Data Identifier Registry

   IANA is to assign subsequent new entries in this registry using the
   Specification Required policy as defined in Section 4.6 of [RFC8126].

8.1.  Guidance for Designated Experts

   The Designated Expert (DE), appointed by the IESG, should ascertain
   the existence of suitable documentation that defines the semantics
   and format of the private data, and verify that the document is
   permanently and publicly available.  Documentation produced outside
   the IETF must not conflict with work that is active or already

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   published within the IETF.  The new Reference field should contain a
   reference to that documentation.

   The Description field should contain the name of the upper-layer
   protocol that generates and uses the private data.

   The DE should assign a new Format Identifier so that it does not
   conflict with existing entries in this registry, and so that it is
   not likely to be mistaken as part of the payload of other registered
   formats.

   The DE shall post the request to the nfsv4 WG mailing list (or a
   successor to that list, if such a list exists), for comment and
   review.  The DE shall approve or deny the request and publish notice
   of the decision within 30 days.

9.  References

9.1.  Normative References

   [IBA]      InfiniBand Trade Association, "InfiniBand Architecture
              Specification Volume 1", Release 1.3, March 2015.

              Available from https://www.infinibandta.org/

   [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>.

   [RFC4506]  Eisler, M., Ed., "XDR: External Data Representation
              Standard", STD 67, RFC 4506, DOI 10.17487/RFC4506, May
              2006, <https://www.rfc-editor.org/info/rfc4506>.

   [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>.

   [RFC5042]  Pinkerton, J. and E. Deleganes, "Direct Data Placement
              Protocol (DDP) / Remote Direct Memory Access Protocol
              (RDMAP) Security", RFC 5042, DOI 10.17487/RFC5042, October
              2007, <https://www.rfc-editor.org/info/rfc5042>.

   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
              Writing an IANA Considerations Section in RFCs", BCP 26,
              RFC 8126, DOI 10.17487/RFC8126, June 2017,
              <https://www.rfc-editor.org/info/rfc8126>.

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   [RFC8166]  Lever, C., Ed., Simpson, W., and T. Talpey, "Remote Direct
              Memory Access Transport for Remote Procedure Call Version
              1", RFC 8166, DOI 10.17487/RFC8166, June 2017,
              <https://www.rfc-editor.org/info/rfc8166>.

   [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>.

9.2.  Informative References

   [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>.

   [RFC5044]  Culley, P., Elzur, U., Recio, R., Bailey, S., and J.
              Carrier, "Marker PDU Aligned Framing for TCP
              Specification", RFC 5044, DOI 10.17487/RFC5044, October
              2007, <https://www.rfc-editor.org/info/rfc5044>.

   [RFC5531]  Thurlow, R., "RPC: Remote Procedure Call Protocol
              Specification Version 2", RFC 5531, DOI 10.17487/RFC5531,
              May 2009, <https://www.rfc-editor.org/info/rfc5531>.

   [RFC5666]  Talpey, T. and B. Callaghan, "Remote Direct Memory Access
              Transport for Remote Procedure Call", RFC 5666,
              DOI 10.17487/RFC5666, January 2010,
              <https://www.rfc-editor.org/info/rfc5666>.

   [RFC6581]  Kanevsky, A., Ed., Bestler, C., Ed., Sharp, R., and S.
              Wise, "Enhanced Remote Direct Memory Access (RDMA)
              Connection Establishment", RFC 6581, DOI 10.17487/RFC6581,
              April 2012, <https://www.rfc-editor.org/info/rfc6581>.

   [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>.

Acknowledgments

   Thanks to Christoph Hellwig and Devesh Sharma for suggesting this
   approach, and to Tom Talpey and Dave Noveck for their expert comments
   and review.  The author also wishes to thank Bill Baker and Greg

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   Marsden for their support of this work.  Also, thanks to expert
   reviewers Sean Hefty and Dave Minturn.

   Special thanks go to document shepherd Brian Pawlowski, Transport
   Area Director Magnus Westerlund, NFSV4 Working Group Chairs David
   Noveck and Spencer Shepler, and NFSV4 Working Group Secretary Thomas
   Haynes.

Author's Address

   Charles Lever
   Oracle Corporation
   United States of America

   Email: chuck.lever@oracle.com

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