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1. Introduction

This document specifies four TCP [RFC793] congestion control algorithms: slow start, congestion avoidance, fast retransmit and fast recovery. These algorithms were devised in [Jac88] and [Jac90]. Their use with TCP is standardized in [RFC1122]. Additional early work in additive-increase, multiplicative-decrease congestion control is given in [CJ89]. Note that [Ste94] provides examples of these algorithms in action and [WS95] provides an explanation of the source code for the BSD implementation of these algorithms.

In addition to specifying these congestion control algorithms, this document specifies what TCP connections should do after a relatively long idle period, as well as specifying and clarifying some of the issues pertaining to TCP ACK generation.

This document obsoletes [RFC2581], which in turn obsoleted [RFC2001].

Document Organization​

This document is organized as follows:

  • Section 2 provides various definitions that will be used throughout the document
  • Section 3 provides a specification of the congestion control algorithms
  • Section 4 outlines concerns related to the congestion control algorithms
  • Section 5 outlines security considerations

Key Words​

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].

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