CUBIC for Fast Long-Distance Networks
draft-ietf-tcpm-cubic-07

Document Type Active Internet-Draft (tcpm WG)
Last updated 2017-11-15 (latest revision 2017-11-13)
Replaces draft-zimmermann-tcpm-cubic
Stream IETF
Intended RFC status Informational
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Stream WG state Submitted to IESG for Publication (wg milestone: Apr 2016 - Submit document on C... )
Document shepherd Yoshifumi Nishida
Shepherd write-up Show (last changed 2017-09-04)
IESG IESG state RFC Ed Queue
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Responsible AD Mirja K├╝hlewind
Send notices to Yoshifumi Nishida <nishida@sfc.wide.ad.jp>
IANA IANA review state Version Changed - Review Needed
IANA action state No IC
RFC Editor RFC Editor state EDIT
TCP Maintenance and Minor Extensions (TCPM) WG                   I. Rhee
Internet-Draft                                                      NCSU
Intended status: Informational                                     L. Xu
Expires: May 17, 2018                                                UNL
                                                                   S. Ha
                                                                Colorado
                                                           A. Zimmermann

                                                               L. Eggert
                                                                  NetApp
                                                        R. Scheffenegger
                                                       November 13, 2017

                 CUBIC for Fast Long-Distance Networks
                        draft-ietf-tcpm-cubic-07

Abstract

   CUBIC is an extension to the current TCP standards.  It differs from
   the current TCP standards only in the congestion control algorithm in
   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
   default by Linux and have been used for many years.  This document
   provides a specification of CUBIC to enable third party
   implementations and to solicit the community feedback through
   experimentation on the performance of CUBIC.

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 May 17, 2018.

Rhee, et al.              Expires May 17, 2018                  [Page 1]
Internet-Draft                    CUBIC                    November 2017

Copyright Notice

   Copyright (c) 2017 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 . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Design principles of CUBIC  . . . . . . . . . . . . . . . . .   4
   4.  CUBIC Congestion Control  . . . . . . . . . . . . . . . . . .   6
     4.1.  Window increase function  . . . . . . . . . . . . . . . .   6
     4.2.  TCP-friendly region . . . . . . . . . . . . . . . . . . .   7
     4.3.  Concave region  . . . . . . . . . . . . . . . . . . . . .   8
     4.4.  Convex region . . . . . . . . . . . . . . . . . . . . . .   8
     4.5.  Multiplicative decrease . . . . . . . . . . . . . . . . .   8
     4.6.  Fast convergence  . . . . . . . . . . . . . . . . . . . .   9
     4.7.  Timeout . . . . . . . . . . . . . . . . . . . . . . . . .   9
     4.8.  Slowstart . . . . . . . . . . . . . . . . . . . . . . . .  10
   5.  Discussion  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     5.1.  Fairness to standard TCP  . . . . . . . . . . . . . . . .  10
     5.2.  Using Spare Capacity  . . . . . . . . . . . . . . . . . .  12
     5.3.  Difficult Environments  . . . . . . . . . . . . . . . . .  13
     5.4.  Investigating a Range of Environments . . . . . . . . . .  13
     5.5.  Protection against Congestion Collapse  . . . . . . . . .  13
     5.6.  Fairness within the Alternative Congestion Control
           Algorithm.  . . . . . . . . . . . . . . . . . . . . . . .  13
     5.7.  Performance with Misbehaving Nodes and Outside Attackers   13
     5.8.  Behavior for Application-Limited Flows  . . . . . . . . .  13
     5.9.  Responses to Sudden or Transient Events . . . . . . . . .  14
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