CUBIC for Fast Long-Distance Networks
draft-eggert-tcpm-rfc8312bis-00
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.
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Please review these documents carefully, as they describe your rights
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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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