RDMA Connection Manager Private Data For RPC-Over-RDMA Version 1
draft-cel-nfsv4-rpcrdma-cm-pvt-msg-02

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Network File System Version 4                                   C. Lever
Internet-Draft                                                    Oracle
Intended status: Informational                        September 18, 2017
Expires: March 22, 2018

    RDMA Connection Manager Private Data For RPC-Over-RDMA Version 1
                 draft-cel-nfsv4-rpcrdma-cm-pvt-msg-02

Abstract

   This document specifies the format of RDMA-CM Private Data exchanged
   between RPC-over-RDMA version 1 peers as a transport connection is
   established.  Such messages indicate peer support for Remote
   Invalidation and larger-than-default inline thresholds.  The message
   format is extensible.

Status of This Memo

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   This Internet-Draft will expire on March 22, 2018.

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Lever                    Expires March 22, 2018                 [Page 1]
Internet-Draft        RPC-Over-RDMA CM Private Data       September 2017

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  Advertised Transport Capabilities . . . . . . . . . . . . . .   3
     3.1.  Inline Threshold Size . . . . . . . . . . . . . . . . . .   3
     3.2.  Remote Invalidation . . . . . . . . . . . . . . . . . . .   4
   4.  Private Data Message Format . . . . . . . . . . . . . . . . .   5
     4.1.  Fixed Mandatory Fields  . . . . . . . . . . . . . . . . .   5
     4.2.  Extending the Message Format  . . . . . . . . . . . . . .   7
   5.  Interoperability Considerations . . . . . . . . . . . . . . .   7
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   8
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   The RPC-over-RDMA version 1 transport protocol enables the use of
   RDMA data transfer for upper layer protocols based on RPC [RFC8166].
   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 maximum size of messages transmitted using RDMA
      Send forces the use of RDMA Read or Write operations even for
      relatively small messages and data payloads.

   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].

   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.

   RPC-over-RDMA version 1 has no means of extending its XDR definition
   such that interoperability with existing implementations is
   preserved.  As a result, an out-of-band mechanism is needed to help
   relieve these limitations for existing RPC-over-RDMA version 1
   implementations.
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