Improving the Round Trip Time Estimation in Internet Routers

published in the Carpathian Journal of Mathematics, ISSN: 1584-2851, Vol. 20, No. 2, pp. 149-154, 2004.
Indexed in: Scopus

Cite as

Full paper

Improving the Round Trip Time Estimation in Internet Routers


Darius Bufnea, Adrian Sterca, Claudiu Cobarzan, Florian Boian
Department of Computer Science, Faculty of Mathematics and Computer Science,
Babeş-Bolyai University of Cluj-Napoca


We review in this paper the concept of TCP-friendliness and we debate one of its weaknesses. Unfortunately, this weakness reduces the practical applicability of the TCP-friendliness equation. For a very high percent of the Internet flows, the TCP-friendliness test may have wrong results. We suggest in this paper a router algorithm that improves the efficiency of the TCP-friendliness equation for some UDP flows. This algorithm uses the additional information retrieved by the router from competing TCP flows in order to obtain a better approximation for the round trip time as used in the TCP-friendliness test.

Key words

congestion control, TCP friendly, TCP time stamp, UDP flows

BibTeX bib file



  1. Allman, M., Paxson, V. and Stevens, W., TCP Congestion Control, IETF RFC 2581, April 1999.
  2. Floyd, S. and Fall, K., Promoting the Use of End-to-End Congestion Control in the Internet, IEEE/ACM Transactions on Networking, Vol. 7, No. 4, pp. 458-472, 1999.
  3. Floyd, S. and Jacobson, V., Random Early Detection Gateways for Congestion Avoidance, IEEE/ACM Trans. Net., Vol. 1, No. 4, August 1993, pp. 397-413.
  4. Floyd, S., A Report on Some Recent Developments in TCP Congestion Control, IEEE Communication Magazine, April 2001.
  5. Jacobson, V., Braden, R. and Borman, D., TCP Extensions for High Performance, IETF RFC 1323, May 1992.
  6. Ramakrishnan, K., Floyd, S. and Black, S., The Addition of Explicit Congestion Notification (ECN) to IP, RFC 3168, September 2001.
  7. Ryu, S., Rump, C. and Qiao, C., Advances in Internet Congestion Control, IEEE Communications Surveys and Tutorials, Vol. 5, No. 1, pp. 28-39, Third Quarter 2003.

Darius Bufnea