Improving round-trip time estimates in reliable transport protocols

ABSTRACT

As a reliable, end-to-end transport protocol, the ARPA Transmission Control Protocol (TCP) uses positive acknowledgements and retransmission to guarantee delivery. TCP implementations are expected to measure and adapt to changing network propagation delays so that its retransmission behavior balances user throughput and network efficiency. However, TCP suffers from a problem we call retransmission ambiguity: when an acknowledgement arrives for a segment that has been retransmitted, there is no indication which transmission is being acknowledged. Many existing TCP implementations do not handle this problem correctly. This paper reviews the various approaches to retransmission and presents a novel and effective approach to the retransmission ambiguity problem.

REFERENCES

• 1: Braden, Robert T., Selective Acknowledgments in TCP. Draft ARPANET Working Group Requests for Comments.
• 2: Clark, David D., Lambert, Mark L., and Zhang, Lixia. NETBLT: A Bulk Data Transfer Protocol; RFC998. In ARPANET Working Group Requests for Comments, no. 998. SRI International, Menlo Park, Calif., March 1987.
• 3: Stephen William Edge, An adaptive timeout algorithm for retransmission across a packet switching network, Proceedings of the ACM SIGCOMM symposium on Communications architectures and protocols: tutorials & symposium, p.248-255, June 06-08, 1984, Montréal, Quebec, Canada, United States
• 4: Hinden, Robert M. and Partridge, Craig. Version 2 of the Reliable Data Protocol. Draft ARPANET Working Group Requests for Comments.
• 5: International Organization for Standards, information processing systems M Open Systems Interconnection m Connection oriented transport protocol specification. International Standard, no. 8073. ISO, Switzerland. 1986.
• 6: Jacobson, Van. Presentation to the Internet End-To-End Services Task Force. April 16, 1987.
• 7: Jacobson, Van. Interpacket Arrival Variance and Mean. Letter to the TCP-IP mailing list, 15 June 1987.
• 8: Jacobson, Van. Retransmit Timers: Theory and Practice, working title of draft paper.
• 9: Jain, Raj, Divergence of Timeout Algorithms for Packet Retransmissions. In Proceedings Fifth Annual International Phoenix Conference on Computers and Communications, Scottsdale, AZ, March 26-28, 1986.
• 10: Kam, P. R., Price, H., Diersing, R. Packet Radio in the Amateur Service. In IEEE Journal on Selected Areas in Communications, May 1985.
• 11: Mills, David. Internet Delay Experiments; RFC889. In ARPANET Working Group Requests for Comments, no. 889. SRI International, Menlo Park, Calif., Dec. 1983.
• 12: Mills, David. Algorithms for Synchronizing Network Clocks; RFC956. In ARPANET Working Group Requests for Comments, no. 956. SRI International, Menlo Park, Calif., Sep. 1985.
• 13: Mills, David. Experiments in Network Clock Synchronization; RFC957. In ARPANET Working Group Requests for Comments, no. 957. SRI International, Menlo Park, Calif., Sep. 1985.
• 14: Mills, David. Network Time Protocol; RFC958. In ARPANET Working Group Requests for Comments, no. 958. SRI International, Menlo Park, Calif., Sep. 1985.
• 15: Morris, Robert J.T. Fixing timeout intervals for lost packet detection in computer communication networks. In AFIPS Conference Proceedings, 1979 National Computer Conference. AFIPS Press, Montvale, Jew Jersey.
• 16: Nagle, John. Congestion Control in IP/TCP Networks; RFC896. In ARPANET Working Group Requests for Comments, no. 896. SRI International, Menlo Park, Calif., Jan. 1984.
• 17: Partridge, Craig. Implementing the Reliable Data Protocol (RDP). In Proceedings of the 1987 Summer USENIX Conference, Phoenix, Arizona.
• 18: Perry, Dennis G. Congestion in the ARPANET. Letter to the TCP-IP Mailing List, October 1, 1986.
• 19: Postel, J., ed. Intemet Protocol; RFC791. In ARPANET Working Group Requests for Comments, no. 791. SRI International, Menlo Park, Calif., Sep. 1981.
• 20: Postel, J., ed. Internet Control Message Protocol; RFC792. In ARPANET Working Group Requests for Comments, no. 792. SRI International, Menlo Park, Calif., Sep. 1981.
• 21: Postel, Jon, ed. Transmission Control Protocol; RFC793. In ARPANET Working Group Requests for Comments, no. 793. SRI International, Menlo Park, Calif., Sep. 1981.
• 22: Velten, David, Hinden, Robert and Sax, Jack. Reliable Data Protocol; RFC908. In ARPANET Working Group Requests for Comments, no. 908. SRI International, Menlo Park, Calif., July 1984.
• 23: Watson, Richard W. Timer-Based Mechanisms in Reliable Transport Protocol Connection Management. Computer Networks 1981, North-Holland Publishing Company.
• 24: L Zhang, Why TCP timers don't work well, Proceedings of the ACM SIGCOMM conference on Communications architectures & protocols, p.397-405, August 05-07, 1986, Stowe, Vermont, United States

INDEX TERMS

Primary Classification:
  C. Computer Systems Organization
  C.2 COMPUTER-COMMUNICATION NETWORKS

Additional Classification:
  K. Computing Milieux
  K.1 THE COMPUTER INDUSTRY
      Subjects: Standards

General Terms:
Algorithms, Design, Measurement, Performance, Reliability, Standardization