Increasing TCP's Initial Window
draft-ietf-tcpm-initcwnd-03

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Document Type Active Internet-Draft (tcpm WG)
Last updated 2012-02-26
Replaces draft-hkchu-tcpm-initcwnd
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Responsible AD Wesley Eddy
Send notices to tcpm-chairs@tools.ietf.org, draft-ietf-tcpm-initcwnd@tools.ietf.org
Internet Draft                                                    J. Chu
draft-ietf-tcpm-initcwnd-03.txt                             N. Dukkipati
Intended status: Experimental                                   Y. Cheng
Updates: 3390, 5681                                            M. Mathis
Expiration date: August 2012                                Google, Inc.
                                                       February 26, 2012

                    Increasing TCP's Initial Window

Status of this Memo

   Distribution of this memo is unlimited.

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Chu, et. al.              Expires August 2012                   [Page 1]
Internet Draft      Increasing TCP's Initial Window        February 2012

Abstract

   This document proposes an increase in the permitted TCP initial
   window (IW) from between 2 and 4 segments, as specified in RFC 3390,
   to 10 segments. It discusses the motivation behind the increase, the
   advantages and disadvantages of the higher initial window, and
   presents results from several large scale experiments showing that
   the higher initial window improves the overall performance of many
   web services without risking congestion collapse. The document closes
   with a discussion of usage and deployment recommended by the IETF TCP
   Maintenance and Minor Extensions (TCPM) working group.

Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  TCP Modification  . . . . . . . . . . . . . . . . . . . . . . . 4
   3.  Implementation Issues . . . . . . . . . . . . . . . . . . . . . 5
   4.  Background  . . . . . . . . . . . . . . . . . . . . . . . . . . 5
   5.  Advantages of Larger Initial Windows  . . . . . . . . . . . . . 7
      5.1 Reducing Latency . . . . . . . . . . . . . . . . . . . . . . 7
      5.2 Keeping up with the growth of web object size  . . . . . . . 7
      5.3 Recovering faster from loss on under-utilized or wireless 
          links  . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
   7.  Disadvantages of Larger Initial Windows for the Network . . . . 9
   8.  Mitigation of Negative Impact . . . . . . . . . . . . . . . .  10
   9.  Interactions with the Retransmission Timer  . . . . . . . . .  10
   10. Experimental Results From Large Scale Cluster Tests . . . . .  10
      10.1 The benefits  . . . . . . . . . . . . . . . . . . . . . .  10
      10.2 The cost  . . . . . . . . . . . . . . . . . . . . . . . .  11
   11. Other Studies . . . . . . . . . . . . . . . . . . . . . . . .  12
   12. Usage and Deployment Recommendations  . . . . . . . . . . . .  13
   13. Related Proposals . . . . . . . . . . . . . . . . . . . . . .  13
   14. Security Considerations . . . . . . . . . . . . . . . . . . .  14
   15. Conclusion  . . . . . . . . . . . . . . . . . . . . . . . . .  14
   16. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
   17. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  14
   Normative References  . . . . . . . . . . . . . . . . . . . . . .  15
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