Requirements for RoCEv3 Congestion Management
draft-chen-iccrg-rocev3-cm-requirements-00

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Last updated 2019-03-23
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INTERNET-DRAFT                                                   F. Chen
Intended Status: Informational                                    W. Sun
Expires: Sep 22, 2019                                              X. Yu
                                                     Huawei Technologies
                                                            Mar 21, 2019

            Requirements for RoCEv3 Congestion Management  
               draft-chen-iccrg-rocev3-cm-requirements-00

Abstract

   On IP-routed datacenter networks, RDMA is deployed using RoCEv2
   protocol. RoCEv2 specification does not define the 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. More and
   more practice of congestion management for RoCEv2 appear in the
   industry, such as DCQCN(Data Center Quantized Congestion
   Notification). There is a demanding for the new RoCEv3 protocol to
   provide stronger congestion management and load balancing mechanisms
   for RDMA deployment in modern datacenter.

Status of this Memo

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Copyright and License Notice

   Copyright (c) 2018 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
   publication of this document. Please review these documents
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   described in the Simplified BSD License.

Table of Contents

   1  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3  Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . .  3
   4  RoCEv3 congestion management requirements . . . . . . . . . . .  4
   5  Current Congestion Management for RoCEv2  . . . . . . . . . . .  4
     5.1 PFC  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  4
     5.2 ECN  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  4
   6. Congestion Management Practice  . . . . . . . . . . . . . . . .  5
     6.1 Packet Retransmission  . . . . . . . . . . . . . . . . . . .  5
     6.2 Congestion Control Mechanisms  . . . . . . . . . . . . . . .  5
     6.3 Re-ordering  . . . . . . . . . . . . . . . . . . . . . . . .  6
     6.4 Load Balancing . . . . . . . . . . . . . . . . . . . . . . .  6
   7  Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . .  6
   8  Security Considerations . . . . . . . . . . . . . . . . . . . .  7
   9  IANA Considerations . . . . . . . . . . . . . . . . . . . . . .  7
   10  References . . . . . . . . . . . . . . . . . . . . . . . . . .  7
   [EVILBIT]  Bellovin, S., "The Security Flag in the IPv4 Header",
              RFC 3514, April 1 2003. . . . . . . . . . . . . . . .   n

 

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1  Introduction

   With the emerging Distributed Storage, AI/HPC, Machine Learning,
   etc., modern datacenter applications demand high throughput(40Gbps
   and above) with ultra-low latency of < 10 microsecond per hop from
   the network, with low CPU overhead. Remote Direct Memory Access
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