Skip to main content

Controlled Delay Active Queue Management

Document Type Replaced Internet-Draft (individual)
Expired & archived
Authors Kathleen Nichols , Van Jacobson , Andrew McGregor , Jana Iyengar
Last updated 2014-10-27 (Latest revision 2014-10-16)
Replaces draft-nichols-tsvwg-codel
Replaced by draft-ietf-aqm-codel
RFC stream (None)
Intended RFC status (None)
Stream Stream state (No stream defined)
Consensus boilerplate Unknown
RFC Editor Note (None)
IESG IESG state Replaced by draft-ietf-aqm-codel
Telechat date (None)
Responsible AD (None)
Send notices to (None)

This Internet-Draft is no longer active. A copy of the expired Internet-Draft is available in these formats:


The "persistently full buffer" problem has been discussed in the IETF community since the early 80's [RFC896]. The IRTF's End-to-End Working Group called for the deployment of active queue management (AQM) to solve the problem in 1998 [RFC2309]. Despite the awareness, the problem has only gotten worse as Moore's Law growth in memory density fueled an exponential increase in buffer pool size. Efforts to deploy AQM have been frustrated by difficult configuration and negative impact on network utilization. This problem, recently christened "bufferbloat", [TSVBB2011] [BB2011] has become increasingly important throughout the Internet but particularly at the consumer edge. This document describes a general framework called CoDel (Controlled Delay) [CODEL2012] that controls bufferbloat-generated excess delay in modern networking environments. CoDel consists of an estimator, a setpoint, and a control loop. It requires no configuration in normal Internet deployments. CoDel comprises some major technical innovations and has been made available as open source so that the framework can be applied by the community to a range of problems. It has been implemented in Linux (and available in the Linux distribution) and deployed in some networks at the consumer edge. In addition, the framework has been successfully applied in other ways. Note: Code Components extracted from this document must include the license as included with the code in Section 5.


Kathleen Nichols
Van Jacobson
Andrew McGregor
Jana Iyengar

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)