Controlled Delay (CoDel) is a newly proposed AQM mechanism developed by Kathleen Nichols and Van Jacobson. CoDel is parameterless and controls the delay, while insensitive to round-trip delays, link rates, and traffic loads. CoDel's patch is originally designed for ns-2.35.

This patch is a slight modification of the original patch and is designed for ns-2.31, mainly to be used along with TCP Evaluation Suite, which is available for ns-2.31 only. However, you can also use it without the TCP Evaluation Suite. 

TCP Evaluation Suite is a standard tool used for the analysis of newly proposed TCP Variants, especially High-Speed TCP Variants. The simulation code of TCP Evaluation Suite is based on original Linux TCP Code. 

CoDel's ns-2.31 patch is designed mainly to assist the community to analyze the interaction of CoDel with existing TCP Variants while using TCP Evaluation Suite.