End-to-end Congestion Control for Flows with Variable Packet Size

Current TCP-friendly congestion control mechanisms such as those used in TFRC adjust the packet rate in order to adapt to network conditions and obtain a throughput not exceeding that of a TCP connection operating under the same conditions. In an environment where the bottleneck resource is packet processing, this is the correct behavior. However, if the bottleneck resource is bandwidth, and flows may use packets of different sizes, resource sharing then depends on packet size and is no longer fair. Now for some applications, such as Internet telephony, it is more natural to adjust the packet size, while keeping the packet rate as constant as possible. In this paper we study the impact of variations in packet size on equation-based congestion control and propose methods to remove the throughput bias resulting from the use of different packet sizes. We investigate in detail the design space of the approaches by means of mathematical analysis and propose a number of possible designs. We evaluate these designs through simulation and conclude with some concrete proposals. Our findings can be used to design a TCP-friendly congestion control mechanism for applications that adjust packet size rather than rate, or that are forced to use a small packet size. We base our analysis on the TFRC protocol, but similar considerations also hold for other congestion control mechanisms.

[1]  Mark Handley,et al.  Equation-based congestion control for unicast applications , 2000, SIGCOMM.

[2]  Donald F. Towsley,et al.  Modeling TCP Reno performance: a simple model and its empirical validation , 2000, TNET.

[3]  Stephen E. Deering,et al.  Path MTU discovery , 1990, RFC.

[4]  Jörg Widmer,et al.  Extending equation-based congestion control to multicast applications , 2001, SIGCOMM '01.

[5]  Sally Floyd,et al.  Adaptive RED: An Algorithm for Increasing the Robustness of RED's Active Queue Management , 2001 .

[6]  B. Goode,et al.  Voice over Internet protocol (VoIP) , 2002, Proc. IEEE.

[7]  Donald F. Towsley,et al.  Adaptive FEC-based error control for Internet telephony , 1999, IEEE INFOCOM '99. Conference on Computer Communications. Proceedings. Eighteenth Annual Joint Conference of the IEEE Computer and Communications Societies. The Future is Now (Cat. No.99CH36320).

[8]  Jean-Yves Le Boudec,et al.  On the long-run behavior of equation-based rate control , 2002, SIGCOMM.

[9]  S. Floyd,et al.  Tcp-friendly unicast rate-based flow control , 1997 .

[10]  Sally Floyd,et al.  Promoting the use of end-to-end congestion control in the Internet , 1999, TNET.

[11]  Fouad A. Tobagi,et al.  Analysis of measured single-hop delay from an operational backbone network , 2002, Proceedings.Twenty-First Annual Joint Conference of the IEEE Computer and Communications Societies.

[12]  Omar Elloumi,et al.  RED behavior with different packet sizes , 2000, Proceedings ISCC 2000. Fifth IEEE Symposium on Computers and Communications.

[13]  George Varghese,et al.  Memory-efficient state lookups with fast updates , 2000, SIGCOMM.

[14]  Victor Firoiu,et al.  A study of active queue management for congestion control , 2000, Proceedings IEEE INFOCOM 2000. Conference on Computer Communications. Nineteenth Annual Joint Conference of the IEEE Computer and Communications Societies (Cat. No.00CH37064).

[15]  Pankaj Gupta,et al.  Algorithms for routing lookups and packet classification , 2000 .

[16]  Jean-Chrysostome Bolot,et al.  Control mechanisms for packet audio in the Internet , 1996, Proceedings of IEEE INFOCOM '96. Conference on Computer Communications.

[17]  B. Barden.  Recommendations on queue management and congestion avoidance in the Internet , 1998 .

[18]  Sridhar Ramesh,et al.  Issues in Model-Based Flow Control , 1999 .

[19]  QUTdN QeO,et al.  Random early detection gateways for congestion avoidance , 1993, TNET.

[20]  Vern Paxson,et al.  TCP Congestion Control , 1999, RFC.

[21]  Deborah Estrin,et al.  Advances in network simulation , 2000, Computer.