Data Center Congestion Management requirements
draft-yueven-tsvwg-dccm-requirements-01

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TSVWG                                                            F. Chen
Internet-Draft                                                    W. Sun
Intended status: Informational                                     X. Yu
Expires: January 8, 2020                   Huawei Technologies Co., Ltd.
                                                            R. Even, Ed.
                                                                  Huawei
                                                            July 7, 2019

             Data Center Congestion Management requirements
                draft-yueven-tsvwg-dccm-requirements-01

Abstract

   On IP-routed datacenter networks, RDMA is deployed using RoCEv2
   protocol or iWARP.  RoCEv2 specification does not define a strong
   congestion management mechanisms and load balancing methods.  RoCEv2
   relies on the existing Link-Layer Flow-Control IEEE
   802.1Qbb(Priority-based Flow Control, PFC) to provide a lossless
   fabric.  RoCEv2 Congestion Management(RCM) use ECN(Explicit
   Congestion Notification, defined in RFC3168) to signal the congestion
   to the destination and use the congestion notification to reduce the
   rate of injection and increase the injection rate when the extent of
   congestion decreases. iWRAP depends on TCP congestion handling.  This
   document describes the current state of flow control and congestion
   handling in the DC and provides requirements for new directions for
   better congestion control.

Status of This Memo

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   This Internet-Draft will expire on January 8, 2020.

Chen, et al.             Expires January 8, 2020                [Page 1]
Internet-Draft              DCCM requirements                  July 2019

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Abbreviations . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Current Congestion Management mechanisms  . . . . . . . . . .   4
     4.1.  Priority-based Flow Control (PFC) . . . . . . . . . . . .   4
     4.2.  Explicit Congestion Notification  . . . . . . . . . . . .   4
   5.  Congestion Management Practice  . . . . . . . . . . . . . . .   5
     5.1.  Packet Retransmission . . . . . . . . . . . . . . . . . .   5
     5.2.  Congestion Control Mechanisms . . . . . . . . . . . . . .   5
       5.2.1.  RTT-based Congestion Control  . . . . . . . . . . . .   5
       5.2.2.  Credit-based Congestion Control . . . . . . . . . . .   6
       5.2.3.  ECN-based Congestion Control  . . . . . . . . . . . .   6
     5.3.  Re-ordering . . . . . . . . . . . . . . . . . . . . . . .   6
     5.4.  Load Balancing  . . . . . . . . . . . . . . . . . . . . .   6
       5.4.1.  Equal-cost multi-path routing (ECMP)  . . . . . . . .   6
       5.4.2.  Flowlet . . . . . . . . . . . . . . . . . . . . . . .   6
       5.4.3.  Per-packet  . . . . . . . . . . . . . . . . . . . . .   7
   6.  Data Center Congestion Management requirements  . . . . . . .   7
   7.  Summary . . . . . . . . . . . . . . . . . . . . . . . . . . .   8
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   8
     10.2.  Informative References . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   With the emerging Distributed Storage, AI/HPC(High Performance
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