RPC-over-RDMA Extensions to Reduce Internode Round-trips
draft-dnoveck-nfsv4-rpcrdma-rtrext-01

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Network File System Version 4                                  D. Noveck
Internet-Draft                                                       HPE
Intended status: Standards Track                        December 3, 2016
Expires: June 6, 2017

        RPC-over-RDMA Extensions to Reduce Internode Round-trips
                 draft-dnoveck-nfsv4-rpcrdma-rtrext-01

Abstract

   It is expected that a future version of the RPC-over-RDMA transport
   will allow protocol extensions to be defined.  This would provide for
   the specification of OPTIONAL features allowing participants who
   implement such features to cooperate as specified by that extension,
   while still interoperating with participants who do not support that
   extension.

   A particular extension is described herein, whose purpose is to
   reduce the latency due to inter-node round-trips needed to effect
   operations which involve direct data placement or which transfer RPC
   messages longer than the fixed inline buffer size limit.

Status of This Memo

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Copyright Notice

   Copyright (c) 2016 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
   (http://trustee.ietf.org/license-info) in effect on the date of

Noveck                    Expires June 6, 2017                  [Page 1]
Internet-Draft       RPC/RDMA Round-trip Reductions        December 2016

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Table of Contents

   1.  Preliminaries . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     1.2.  Introduction  . . . . . . . . . . . . . . . . . . . . . .   3
     1.3.  Prerequisites . . . . . . . . . . . . . . . . . . . . . .   3
     1.4.  Role Terminology  . . . . . . . . . . . . . . . . . . . .   4
   2.  Extension Overview  . . . . . . . . . . . . . . . . . . . . .   5
   3.  Direct Data Placement Features  . . . . . . . . . . . . . . .   5
     3.1.  Current Situation . . . . . . . . . . . . . . . . . . . .   5
     3.2.  RDMA_MSGP . . . . . . . . . . . . . . . . . . . . . . . .   5
     3.3.  Send-based DDP  . . . . . . . . . . . . . . . . . . . . .   7
     3.4.  Other DDP-Related Extensions  . . . . . . . . . . . . . .   7
   4.  Message Continuation Feature  . . . . . . . . . . . . . . . .   8
     4.1.  Current Situation . . . . . . . . . . . . . . . . . . . .   8
     4.2.  Message Continuation Changes  . . . . . . . . . . . . . .   9
     4.3.  Message Continuation and Credits  . . . . . . . . . . . .   9
   5.  Using Protocol Additions  . . . . . . . . . . . . . . . . . .  10
     5.1.  New Operation Support . . . . . . . . . . . . . . . . . .  10
     5.2.  Message Continuation Support  . . . . . . . . . . . . . .  11
     5.3.  Send-based DDP Support  . . . . . . . . . . . . . . . . .  11
     5.4.  Error Reporting . . . . . . . . . . . . . . . . . . . . .  12
   6.  XDR Preliminaries . . . . . . . . . . . . . . . . . . . . . .  13
     6.1.  Message Continuation Preliminaries  . . . . . . . . . . .  13
     6.2.  Data Placement Preliminaries  . . . . . . . . . . . . . .  14
   7.  Data Placement Structures . . . . . . . . . . . . . . . . . .  17
     7.1.  Data Placement Overview . . . . . . . . . . . . . . . . .  17
     7.2.  Buffer Structure Definition . . . . . . . . . . . . . . .  18
     7.3.  Message DDP Structures  . . . . . . . . . . . . . . . . .  20
     7.4.  Response Direction DDP Structures . . . . . . . . . . . .  21
   8.  Transport Properties  . . . . . . . . . . . . . . . . . . . .  24
     8.1.  Property List . . . . . . . . . . . . . . . . . . . . . .  24
     8.2.  RTR Support Property  . . . . . . . . . . . . . . . . . .  25
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