CUBIC for Fast and Long-Distance Networks
draft-ietf-tcpm-rfc8312bis-00

Document Type Active Internet-Draft (tcpm WG)
Authors Lisong Xu  , Sangtae Ha  , Injong Rhee  , Vidhi Goel  , Lars Eggert 
Last updated 2021-03-15
Replaces draft-eggert-tcpm-rfc8312bis
Stream Internet Engineering Task Force (IETF)
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TCPM                                                               L. Xu
Internet-Draft                                                       UNL
Obsoletes: 8312 (if approved)                                      S. Ha
Intended status: Standards Track                                Colorado
Expires: 16 September 2021                                       I. Rhee
                                                                  Bowery
                                                                 V. Goel
                                                              Apple Inc.
                                                          L. Eggert, Ed.
                                                                  NetApp
                                                           15 March 2021

               CUBIC for Fast and Long-Distance Networks
                     draft-ietf-tcpm-rfc8312bis-00

Abstract

   CUBIC is an extension to the traditional TCP standards.  It differs
   from the traditional TCP standards only in the congestion control
   algorithm on the sender side.  In particular, it uses a cubic
   function instead of the linear window increase function of the
   traditional TCP standards to improve scalability and stability under
   fast and long-distance networks.  CUBIC has been adopted as the
   default TCP congestion control algorithm by the Linux, Windows, and
   Apple stacks.

   This document updates the specification of CUBIC to include
   algorithmic improvements based on these implementations and recent
   academic work.  Based on the extensive deployment experience with
   CUBIC, it also moves the specification to the Standards Track,
   obsoleting [RFC8312].

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.

Xu, et al.              Expires 16 September 2021               [Page 1]
Internet-Draft                    CUBIC                       March 2021

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   This Internet-Draft will expire on 16 September 2021.

Copyright Notice

   Copyright (c) 2021 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
     3.1.  Principle 1 for the CUBIC Increase Function . . . . . . .   5
     3.2.  Principle 2 for AIMD Friendliness . . . . . . . . . . . .   6
     3.3.  Principle 3 for RTT Fairness  . . . . . . . . . . . . . .   6
     3.4.  Principle 4 for the CUBIC Decrease Factor . . . . . . . .   7
   4.  CUBIC Congestion Control  . . . . . . . . . . . . . . . . . .   7
     4.1.  Definitions . . . . . . . . . . . . . . . . . . . . . . .   7
       4.1.1.  Constants of Interest . . . . . . . . . . . . . . . .   7
       4.1.2.  Variables of Interest . . . . . . . . . . . . . . . .   8
     4.2.  Window Increase Function  . . . . . . . . . . . . . . . .   9
     4.3.  AIMD-Friendly Region  . . . . . . . . . . . . . . . . . .  10
     4.4.  Concave Region  . . . . . . . . . . . . . . . . . . . . .  12
     4.5.  Convex Region . . . . . . . . . . . . . . . . . . . . . .  12
     4.6.  Multiplicative Decrease . . . . . . . . . . . . . . . . .  13
     4.7.  Fast Convergence  . . . . . . . . . . . . . . . . . . . .  13
     4.8.  Timeout . . . . . . . . . . . . . . . . . . . . . . . . .  14
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