Increasing Maximum Window Size of TCP
draft-nishida-tcpm-maxwin-03

Document Type Active Internet-Draft (individual)
Last updated 2017-01-30
Stream (None)
Intended RFC status (None)
Formats plain text xml pdf html bibtex
Stream Stream state (No stream defined)
Consensus Boilerplate Unknown
RFC Editor Note (None)
IESG IESG state I-D Exists
Telechat date
Responsible AD (None)
Send notices to (None)
Network Working Group                                         Y. Nishida
Internet-Draft                                        GE Global Research
Intended status: Experimental                                    H. Asai
Expires: August 3, 2017                          The University of Tokyo
                                                              M. Bagnulo
                                                                    UC3M
                                                        January 30, 2017

                 Increasing Maximum Window Size of TCP
                    draft-nishida-tcpm-maxwin-03.txt

Abstract

   This document proposes to increase the current max window size
   allowed in TCP.  It describes the current logic that limits the
   maximum window size and provides a rationale to relax the limitation
   as well as the negotiation mechanism to enable this feature safely.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on August 3, 2017.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of

Nishida, et al.          Expires August 3, 2017                 [Page 1]
Internet-Draft               Increase Maxwin                January 2017

   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions and Terminology . . . . . . . . . . . . . . . . .   2
   3.  Increasing Maximum Window Size  . . . . . . . . . . . . . . .   3
   4.  Updating the Window Scale Option  . . . . . . . . . . . . . .   4
   5.  Use Cases, Benefits to Explore Maximum Window Size  . . . . .   5
   6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   6
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   TCP throughput is determined by two factors: Round Trip Time and
   Receive Window size.  It can never exceed Receive Window size divided
   by RTT.  This implies larger window size is important to achieve
   better performance.  Original TCP's maximum window size defined in
   RFC793 [RFC0793] is 2^16 -1 (65,535), however, RFC7323 [RFC7323]
   defines TCP Window Scale option which allows TCP to use larger window
   size.  Window Scale uses a shift count stored in 1-byte field in the
   option.  The receiver of the option uses left-shifted window size
   value by the shift count as actual window size.  When Window Scale is
   used, TCP can extend maximum window size to 2^30 - 2^14
   (1,073,725,440).  This is because the maximum shift count is 14 as
   described in the Section 2.3 of RFC7323 [RFC7323].  However, since
   TCP's sequence number space is 2^32, we believe it is still possible
   to use larger window size than this while careful design of the logic
   that can identify segments inside the window is required.  In this
   document, we propose to increase the maximum shift count to 15, which
   extend window size to 2^31 - 2^15.

2.  Conventions and Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
Show full document text