CUBIC for Fast Long-Distance Networks
draft-eggert-tcpm-rfc8312bis-00

Document Type Active Internet-Draft (individual)
Authors Lisong Xu  , Sangtae Ha  , Lars Eggert 
Last updated 2020-11-15
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TCPM                                                               L. Xu
Internet-Draft                                                       UNL
Obsoletes: 8312 (if approved)                                      S. Ha
Intended status: Standards Track                                Colorado
Expires: 19 May 2021                                      L. Eggert, Ed.
                                                                  NetApp
                                                        15 November 2020

                 CUBIC for Fast Long-Distance Networks
                    draft-eggert-tcpm-rfc8312bis-00

Abstract

   CUBIC is an extension to the current TCP standards.  It differs from
   the current TCP standards only in the congestion control algorithm on
   the sender side.  In particular, it uses a cubic function instead of
   a linear window increase function of the current TCP standards to
   improve scalability and stability under fast and long-distance
   networks.  CUBIC and its predecessor algorithm have been adopted as
   defaults by Linux and have been used for many years.  This document
   provides a specification of CUBIC to enable third-party
   implementations and to solicit community feedback through
   experimentation on the performance of CUBIC.

   This documents obsoletes [RFC8312], updating the specification of
   CUBIC to conform to the current Linux version.

Note to Readers

   Discussion of this draft takes place on the TCPM working group
   mailing list (mailto:tcpm@ietf.org), which is archived at
   https://mailarchive.ietf.org/arch/browse/tcpm/.

   Working Group information can be found at
   https://datatracker.ietf.org/wg/tcpm/; source code and issues list
   for this draft can be found at https://github.com/NTAP/rfc8312bis.

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/.

Xu, et al.                 Expires 19 May 2021                  [Page 1]
Internet-Draft                    CUBIC                    November 2020

   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 19 May 2021.

Copyright Notice

   Copyright (c) 2020 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 the Trust Legal Provisions and are
   provided without warranty as described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Conventions . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Design Principles of CUBIC  . . . . . . . . . . . . . . . . .   4
   4.  CUBIC Congestion Control  . . . . . . . . . . . . . . . . . .   6
     4.1.  Window Increase Function  . . . . . . . . . . . . . . . .   7
     4.2.  TCP-Friendly Region . . . . . . . . . . . . . . . . . . .   8
     4.3.  Concave Region  . . . . . . . . . . . . . . . . . . . . .   8
     4.4.  Convex Region . . . . . . . . . . . . . . . . . . . . . .   9
     4.5.  Multiplicative Decrease . . . . . . . . . . . . . . . . .   9
     4.6.  Fast Convergence  . . . . . . . . . . . . . . . . . . . .   9
     4.7.  Timeout . . . . . . . . . . . . . . . . . . . . . . . . .  10
     4.8.  Slow Start  . . . . . . . . . . . . . . . . . . . . . . .  10
   5.  Discussion  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     5.1.  Fairness to Standard TCP  . . . . . . . . . . . . . . . .  11
     5.2.  Using Spare Capacity  . . . . . . . . . . . . . . . . . .  13
     5.3.  Difficult Environments  . . . . . . . . . . . . . . . . .  14
     5.4.  Investigating a Range of Environments . . . . . . . . . .  14
     5.5.  Protection against Congestion Collapse  . . . . . . . . .  14
     5.6.  Fairness within the Alternative Congestion Control
            Algorithm  . . . . . . . . . . . . . . . . . . . . . . .  14
     5.7.  Performance with Misbehaving Nodes and Outside
            Attackers  . . . . . . . . . . . . . . . . . . . . . . .  14
     5.8.  Behavior for Application-Limited Flows  . . . . . . . . .  15
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