Data Center Fast Congestion Management
draft-even-iccrg-dc-fast-congestion-00

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TSVWG                                                            R. Even
Internet-Draft                                                    Huawei
Intended status: Informational                                  R. Huang
Expires: April 25, 2020                    Huawei Technologies Co., Ltd.
                                                        October 23, 2019

                 Data Center Fast Congestion Management
                 draft-even-iccrg-dc-fast-congestion-00

Abstract

   Fast congestion control is discussed in academic papers as well as in
   the different standard bodies.  There is no one proposal for
   providing a solution that will work for all use cases leading to
   multiple approaches.  By congestion control we refer to an end to end
   solution and not only to the congestion control algorithm on the
   sender side.  This document describes the current state of flow
   control and congestion for Data Centers and proposes future
   directions.

Status of This Memo

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   This Internet-Draft will expire on April 25, 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
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Even & Huang             Expires April 25, 2020                 [Page 1]
Internet-Draft             DC Fast Congestion               October 2019

   to this document.  Code Components extracted from this document must
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Abbreviations . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Alternative Congestion Management mechanisms  . . . . . . . .   4
     4.1.  Mechanisms based on estimation of network status  . . . .   4
     4.2.  Network provides limited information  . . . . . . . . . .   4
       4.2.1.  ECN and DCTCP . . . . . . . . . . . . . . . . . . . .   5
       4.2.2.  DCQCN . . . . . . . . . . . . . . . . . . . . . . . .   5
       4.2.3.  SCE - Some Congestion Experienced . . . . . . . . . .   6
       4.2.4.  L4S - Low Latency, Low Loss, Scalable Throughput  . .   7
     4.3.  Network provides more information . . . . . . . . . . . .   8
     4.4.  Network provides proactive control  . . . . . . . . . . .   9
   5.  Summary and Proposal  . . . . . . . . . . . . . . . . . . . .   9
     5.1.  Reflect the network status more accurately  . . . . . . .  10
     5.2.  Notify the reaction point as soon as possible.  . . . . .  10
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  15

1.  Introduction

   Fast congestion control is discussed in academic papers as well as in
   the different standard bodies.  There is no one proposal for
   providing a solution that will work for all use cases leading to
   multiple approaches.  By congestion control we refer to an end to end
   solution and not only to the congestion control algorithm on the
   sender side.

   The major use case that we are looking at is congestion control for
   Data Centers, a controlled environment[RFC8085].  With the emerging
   Distributed Storage, AI/HPC (High Performance Computing), Machine
   Learning, etc., modern datacenter applications demand high
   throughput(40Gbps and above) with ultra-low latency of less than 10
   microsecond per hop from the network, with low CPU overhead.  For the
   end to end the latency should be less than 50usec, this value is
   based on DCQCN [DCQCN] The high link speed (>40Gb/s) in Data Centers