RDMA Connection Manager Private Data For RPC-Over-RDMA Version 1
draft-ietf-nfsv4-rpcrdma-cm-pvt-data-00

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Network File System Version 4                                   C. Lever
Internet-Draft                                                    Oracle
Intended status: Informational                             July 25, 2018
Expires: January 26, 2019

    RDMA Connection Manager Private Data For RPC-Over-RDMA Version 1
                draft-ietf-nfsv4-rpcrdma-cm-pvt-data-00

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 private data is used to indicate peer support for
   remote invalidation and larger-than-default inline thresholds.  The
   data format is extensible.

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
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   This Internet-Draft will expire on January 26, 2019.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  Advertised Transport Properties . . . . . . . . . . . . . . .   3
   4.  Private Data Message Format . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   9
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  10

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 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.

   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].

   RPC-over-RDMA version 1 has no means of extending its XDR 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
   purpose of this message format is two-fold:

   o  To provide immediate relief from certain performance constraints
      inherent in RPC-over-RDMA version 1

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   o  To enable experimentation with parameters of the base RDMA
      transport over which RPC-over-RDMA runs

2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",