Congestion Control Principles (RFC2914)
Original Publication Date: 2000-Sep-01
Included in the Prior Art Database: 2019-Feb-13
Internet Society Requests For Comment (RFCs)
The goal of this document is to explain the need for congestion control in the Internet, and to discuss what constitutes correct congestion control. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.
Network Working Group S. Floyd Request for Comments: 2914 ACIRI BCP: 41 September 2000 Category: Best Current Practice
Congestion Control Principles
Status of this Memo
This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. Distribution of this memo is unlimited.
Copyright (C) The Internet Society (2000). All Rights Reserved.
The goal of this document is to explain the need for congestion control in the Internet, and to discuss what constitutes correct congestion control. One specific goal is to illustrate the dangers of neglecting to apply proper congestion control. A second goal is to discuss the role of the IETF in standardizing new congestion control protocols.
This document draws heavily from earlier RFCs, in some cases reproducing entire sections of the text of earlier documents [RFC2309, RFC2357]. We have also borrowed heavily from earlier publications addressing the need for end-to-end congestion control [FF99].
2. Current standards on congestion control
IETF standards concerning end-to-end congestion control focus either on specific protocols (e.g., TCP [RFC2581], reliable multicast protocols [RFC2357]) or on the syntax and semantics of communications between the end nodes and routers about congestion information (e.g., Explicit Congestion Notification [RFC2481]) or desired quality-of- service (diff-serv)). The role of end-to-end congestion control is also discussed in an Informational RFC on "Recommendations on Queue Management and Congestion Avoidance in the Internet" [RFC2309]. RFC 2309 recommends the deployment of active queue management mechanisms in routers, and the continuation of design efforts towards mechanisms
Floyd, ed. Best Current Practice [Page 1]
RFC 2914 Congestion Control Principles September 2000
in routers to deal with flows that are unresponsive to congestion notification. We freely borrow from RFC 2309 some of their general discussion of end-to-end congestion control.
In contrast to the RFCs discussed above, this document is a more general discussion of the principles of congestion control. One of the keys to the success of the Internet has been the congestion avoidance mechanisms of TCP. While TCP is still the dominant transport protocol in the Internet, it is not ubiquitous, and there are an increasing number of applications that, for one reason or another, choose not to use TCP. Such traffic includes not only multicast traffic, but unicast traffic such as streaming multimedia that does not require reliability; and traffic such as DNS or routing messages that consist of short transfers deemed critical to the operation of the network. Much of this traffic does not use any form of either bandwidth reservations or end-to-end congestion control. The continued use of end-to-end congestion control by best-effort traffic is critical for maintaining the stability of the Internet.