Recommendations on Queue Management and Congestion Avoidance in the Internet
RFC 2309
Document | Type |
RFC - Informational
(April 1998; No errata)
Obsoleted by RFC 7567
Updated by RFC 7141
Was draft-irtf-e2e-queue-mgt (individual)
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Authors | David Clark , Greg Minshall , Lixia Zhang , Larry Peterson , K. Ramakrishnan , John Wroclawski , Scott Shenker , Craig Partridge , Jon Crowcroft , Robert Braden , Steve Deering , Sally Floyd , Bruce Davie , Van Jacobson , Deborah Estrin | ||
Last updated | 2013-03-02 | ||
Stream | Legacy | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | Legacy state | (None) | |
Consensus Boilerplate | Unknown | ||
RFC Editor Note | (None) | ||
IESG | IESG state | RFC 2309 (Informational) | |
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group B. Braden, USC/ISI Request for Comments: 2309 D. Clark, MIT LCS Category: Informational J. Crowcroft, UCL B. Davie, Cisco Systems S. Deering, Cisco Systems D. Estrin, USC S. Floyd, LBNL V. Jacobson, LBNL G. Minshall, Fiberlane C. Partridge, BBN L. Peterson, University of Arizona K. Ramakrishnan, ATT Labs Research S. Shenker, Xerox PARC J. Wroclawski, MIT LCS L. Zhang, UCLA April 1998 Recommendations on Queue Management and Congestion Avoidance in the Internet Status of Memo This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (1998). All Rights Reserved. Abstract This memo presents two recommendations to the Internet community concerning measures to improve and preserve Internet performance. It presents a strong recommendation for testing, standardization, and widespread deployment of active queue management in routers, to improve the performance of today's Internet. It also urges a concerted effort of research, measurement, and ultimate deployment of router mechanisms to protect the Internet from flows that are not sufficiently responsive to congestion notification. Braden, et. al. Informational [Page 1] RFC 2309 Internet Performance Recommendations April 1998 1. INTRODUCTION The Internet protocol architecture is based on a connectionless end- to-end packet service using the IP protocol. The advantages of its connectionless design, flexibility and robustness, have been amply demonstrated. However, these advantages are not without cost: careful design is required to provide good service under heavy load. In fact, lack of attention to the dynamics of packet forwarding can result in severe service degradation or "Internet meltdown". This phenomenon was first observed during the early growth phase of the Internet of the mid 1980s [Nagle84], and is technically called "congestion collapse". The original fix for Internet meltdown was provided by Van Jacobson. Beginning in 1986, Jacobson developed the congestion avoidance mechanisms that are now required in TCP implementations [Jacobson88, HostReq89]. These mechanisms operate in the hosts to cause TCP connections to "back off" during congestion. We say that TCP flows are "responsive" to congestion signals (i.e., dropped packets) from the network. It is primarily these TCP congestion avoidance algorithms that prevent the congestion collapse of today's Internet. However, that is not the end of the story. Considerable research has been done on Internet dynamics since 1988, and the Internet has grown. It has become clear that the TCP congestion avoidance mechanisms [RFC2001], while necessary and powerful, are not sufficient to provide good service in all circumstances. Basically, there is a limit to how much control can be accomplished from the edges of the network. Some mechanisms are needed in the routers to complement the endpoint congestion avoidance mechanisms. It is useful to distinguish between two classes of router algorithms related to congestion control: "queue management" versus "scheduling" algorithms. To a rough approximation, queue management algorithms manage the length of packet queues by dropping packets when necessary or appropriate, while scheduling algorithms determine which packet to send next and are used primarily to manage the allocation of bandwidth among flows. While these two router mechanisms are closely related, they address rather different performance issues. This memo highlights two router performance issues. The first issue is the need for an advanced form of router queue management that we call "active queue management." Section 2 summarizes the benefits that active queue management can bring. Section 3 describes a recommended active queue management mechanism, called Random Early Detection or "RED". We expect that the RED algorithm can be usedShow full document text