RFC 8312 · INFORMATIONAL · 2018

CUBIC for Fast Long-Distance Networks

Overview

RFC 8312, “CUBIC for Fast Long-Distance Networks”, is an Informational document published in February 2018 by I. Rhee, L. Xu, S. Ha, A. Zimmermann, L. Eggert, R. Scheffenegger. It has been obsoleted by RFC 9438 — refer to the newer document for the authoritative version. The canonical text is published by the RFC Editor.

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.

Abstract as published in the RFC, via rfc-editor.org.

What “Informational” means

Published for the general information of the community. It does not define an IETF standard and carries no standards-track status.

Read this RFC

The canonical text of RFC 8312 is hosted at rfc-editor.org. Available in TXT,HTML.

Relationships to other RFCs
Obsoleted by
RFC 9438
Other RFCs from 2018

Who Is Online

In total there are 43 users online: 0 registered, 37 guests and 6 bots.

Most users ever online was 1,226 on 13 Jun 2026, 3:56 am.

Bots: AhrefsBot Applebot Facebook Other Bot SemrushBot Sogou

Users active in the past 15 minutes. Total registered members: 354