RFC 2415 (rfc2415) - Page 1 of 11
Simulation Studies of Increased Initial TCP Window Size
Alternative Format: Original Text Document
Network Working Group K. Poduri
Request for Comments: 2415 K. Nichols
Category: Informational Bay Networks
September 1998
Simulation Studies of Increased Initial TCP Window Size
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (1998). All Rights Reserved.
Abstract
An increase in the permissible initial window size of a TCP
connection, from one segment to three or four segments, has been
under discussion in the tcp-impl working group. This document covers
some simulation studies of the effects of increasing the initial
window size of TCP. Both long-lived TCP connections (file transfers)
and short-lived web-browsing style connections were modeled. The
simulations were performed using the publicly available ns-2
simulator and our custom models and files are also available.
1. Introduction
We present results from a set of simulations with increased TCP
initial window (IW). The main objectives were to explore the
conditions under which the larger IW was a "win" and to determine the
effects, if any, the larger IW might have on other traffic flows
using an IW of one segment.
This study was inspired by discussions at the Munich IETF tcp-impl
and tcp-sat meetings. A proposal to increase the IW size to about 4K
bytes (4380 bytes in the case of 1460 byte segments) was discussed.
Concerns about both the utility of the increase and its effect on
other traffic were raised. Some studies were presented showing the
positive effects of increased IW on individual connections, but no
studies were shown with a wide variety of simultaneous traffic flows.
It appeared that some of the questions being raised could be
addressed in an ns-2 simulation. Early results from our simulations
were previously posted to the tcp-impl mailing list and presented at
the tcp-impl WG meeting at the December 1997 IETF.
Poduri & Nichols Informational