Fast Congestion Response
draft-even-fast-congestion-response-00

Document Type Active Internet-Draft (individual)
Last updated 2019-03-10
Stream (None)
Intended RFC status (None)
Formats plain text pdf html bibtex
Stream Stream state (No stream defined)
Consensus Boilerplate Unknown
On Agenda Hot RFC Lightning Talks at IETF-104
RFC Editor Note (None)
IESG IESG state I-D Exists
Telechat date
Responsible AD (None)
Send notices to (None)
TSVWG                                                            R. Even
Internet-Draft                                                    Huawei
Intended status: Informational                            March 10, 2019
Expires: September 11, 2019

                        Fast Congestion Response
                 draft-even-fast-congestion-response-00

Abstract

   The high link speed (100Gb/s) in Data Centers (DC) are making network
   transfers complete faster and in fewer RTTs.  The short data bursts
   requires low latency while longer data transfer require high
   throughput.  This document describes the current state of flow
   control and congestion handling in the DC using RoCEv2 and suggests
   new directions for faster congestion control.

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 11, 2019.

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
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of

Even                   Expires September 11, 2019               [Page 1]
Internet-Draft          Fast Congestion Response              March 2019

   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Problem statement . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   4
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   The high link speed (100Gb/s) in Data Centers (DC) are making network
   transfers complete faster and in fewer RTTs.  Network traffic in a
   data center is often a mix of short and long flows, where the short
   flows require low latencies and the long flows require high
   throughputs.  [RFC8257] titled Data Center TCP (DCTCP): TCP
   Congestion Control for Data Centers is an Informational RFC that
   extends the Explicit Congestion Notification (ECN) [RFC3168]
   processing to estimate the fraction of bytes that encounter
   congestion, DCTCP then scales the TCP congestion window based on this
   estimate.  DCTCP does not change the ECN reporting in TCP.  Other ECN
   notification mechanisms are specified for RTP in [RFC6679] and for
   QUIC [I-D.ietf-quic-transport].  The ECN notification are reported
   from the end receiver to the sender and the notification includes
   only the occurrence of ECN in the TCP case and the number of ECN
   marked packet for RTP and QUIC.  What is common for TCP, RTP and QUIC
   is that the switches in the middle just monitor and report while the
   analysis and the rate control are done by the data sender.

   In Data Centers the InfiniBand Architecture (IBA) offers a rich set
   of I/O services based on an RDMA access method and message passing
   semantics.  RDMA over Converged Ethernet (RoCEv2) [RoCEv2] is using
   UDP as the transport for RDMA.  RoCEv2 Congestion Management (RCM)
   provides the capability to avoid congestion hot spots and optimize
   the throughput of the fabric.  RCM relies on the Link-Layer Flow-
   Control IEEE 802.1Qbb(PFC) to provide a lossless network.  RoCEv2
   Congestion Management(RCM) use ECN [RFC3168] to signal the congestion
   to the destination.  The ECN notification is sent back from the
   receiver to the data sender using RoCEv2 Congestion Notification
   Packet (CNP) that notifies the sender about ECN marked packets.  The
   rate reduction by the sender as well as the increase in data
Show full document text