CUBIC for Fast Long-Distance Networks
draft-ietf-tcpm-cubic-02

The information below is for an old version of the document
Document Type Active Internet-Draft (tcpm WG)
Authors Injong Rhee  , Lisong Xu  , Sangtae Ha  , Alexander Zimmermann  , Lars Eggert  , Richard Scheffenegger 
Last updated 2016-08-07
Replaces draft-zimmermann-tcpm-cubic
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Intended RFC status Informational
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TCP Maintenance and Minor Extensions (TCPM) WG                   I. Rhee
Internet-Draft                                                      NCSU
Intended status: Informational                                     L. Xu
Expires: February 6, 2017                                            UNL
                                                                   S. Ha
                                                                Colorado
                                                           A. Zimmermann
                                                               L. Eggert
                                                        R. Scheffenegger
                                                                  NetApp
                                                          August 5, 2016

                 CUBIC for Fast Long-Distance Networks
                        draft-ietf-tcpm-cubic-02

Abstract

   CUBIC is an extension to the current TCP standards.  The protocol
   differs from the current TCP standards only in the congestion window
   adjustment function in the sender side.  In particular, it uses a
   cubic function instead of a linear window increase of the current TCP
   standards to improve scalability and stability under fast and long
   distance networks.  BIC-TCP, a predecessor of CUBIC, has been a
   default TCP adopted by Linux since year 2005 and has already been
   deployed globally and in use for several years by the Internet
   community at large.  CUBIC is using a similar window growth function
   as BIC-TCP and is designed to be less aggressive and fairer to TCP in
   bandwidth usage than BIC-TCP while maintaining the strengths of BIC-
   TCP such as stability, window scalability and RTT fairness.  Through
   extensive testing in various Internet scenarios, we believe that
   CUBIC is safe for deployment and testing in the global Internet.  The
   intent of this document is to provide the protocol specification of
   CUBIC for a third party implementation and 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 http://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

Rhee, et al.            Expires February 6, 2017                [Page 1]
Internet-Draft                    CUBIC                      August 2016

   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 February 6, 2017.

Copyright Notice

   Copyright (c) 2016 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
   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 . . . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  CUBIC Congestion Control  . . . . . . . . . . . . . . . . . .   5
     3.1.  Window growth function  . . . . . . . . . . . . . . . . .   5
     3.2.  TCP-friendly region . . . . . . . . . . . . . . . . . . .   6
     3.3.  Concave region  . . . . . . . . . . . . . . . . . . . . .   7
     3.4.  Convex region . . . . . . . . . . . . . . . . . . . . . .   7
     3.5.  Multiplicative decrease . . . . . . . . . . . . . . . . .   7
     3.6.  Fast convergence  . . . . . . . . . . . . . . . . . . . .   7
   4.  Discussion  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     4.1.  Fairness to standard TCP  . . . . . . . . . . . . . . . .   8
     4.2.  Using Spare Capacity  . . . . . . . . . . . . . . . . . .  10
     4.3.  Difficult Environments  . . . . . . . . . . . . . . . . .  11
     4.4.  Investigating a Range of Environments . . . . . . . . . .  11
     4.5.  Protection against Congestion Collapse  . . . . . . . . .  11
     4.6.  Fairness within the Alternative Congestion Control
           Algorithm.  . . . . . . . . . . . . . . . . . . . . . . .  11
     4.7.  Performance with Misbehaving Nodes and Outside Attackers   11
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