TCP congestion avoidance algorithm identification

Peng Yang, Wen Luo, Lisong Xu, Jitender Deogun, Ying Lu

Research output: Chapter in Book/Report/Conference proceedingConference contribution

40 Scopus citations


The Internet has recently been evolving from homogeneous congestion control to heterogeneous congestion control. Several years ago, Internet traffic was mainly controlled by the traditional AIMD algorithm, whereas Internet traffic is now controlled by many different TCP algorithms, such as AIMD, BIC, CUBIC, and CTCP. However, there is very little work on the performance and stability study of the Internet with heterogeneous congestion control. One fundamental reason is the lack of the deployment information of different TCP algorithms. In this paper, we first propose a tool called TCP Congestion Avoidance Algorithm Identification (CAAI) for actively identifying the TCP algorithm of a remote web server. CAAI can identify all default TCP algorithms (i.e., AIMD, BIC, CUBIC, and CTCP) and most non-default TCP algorithms of major operating system families. We then present, for the first time, the CAAI measurement result of the 5000 most popular web servers. Among the web servers with valid traces, we found that only 16.85∼25.58% of web servers still use the traditional AIMD, 44.51% of web servers use BIC or CUBIC, and 10.27∼19% of web servers use CTCP. In addition, we found that, for the first time, some web servers use non-default TCP algorithms, some web servers use some unknown TCP algorithms which are not available in any major operating system family, and some web servers use abnormal slow start algorithms. Our CAAI measurement results show a strong sign that the majority of TCP flows are not controlled by AIMD anymore, and a strong sign that the Internet congestion control has already changed from homogeneous to highly heterogeneous.

Original languageEnglish (US)
Title of host publicationProceedings - 31st International Conference on Distributed Computing Systems, ICDCS 2011
Number of pages12
StatePublished - 2011
Event31st International Conference on Distributed Computing Systems, ICDCS 2011 - Minneapolis, MN, United States
Duration: Jun 20 2011Jul 24 2011

Publication series

NameProceedings - International Conference on Distributed Computing Systems


Conference31st International Conference on Distributed Computing Systems, ICDCS 2011
Country/TerritoryUnited States
CityMinneapolis, MN


  • Heterogeneous congestion control
  • Internet measurement
  • TCP congestion control

ASJC Scopus subject areas

  • Software
  • Hardware and Architecture
  • Computer Networks and Communications


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