Steven,
After reading your trials in changing the TCP window size in Windows98
beta, the Internet protocols team at NASA Lewis Research Center decided to
have a go at it. Using two machines in our TCP/HTTP/Multicast testbed, we
verified Windows98 is capable of using large windows and SACKs.
Test Setup:
A Windows98 beta machine with 10/100Mbps 3Com card talking through a
10Mbps hub to a NetBSD 1.2.1 machine with an identical 3Com card. The
NetBSD machine has large windows enabled in the kernel. We have the
capability to insert both an emulated delay or real delay over NASA's ACTS,
but a delay was not used for these tests.
The Windows98 machine had the following entries in the registry:
Hkey_Local_Machine\System\CurrentControlSet\Services\VxD\MSTCP
DefaultRcvWindow = 102400 (string)
Hkey_Local_Machine\System\CurrentControlSet\Services\VxD\MSTCP
DefaultSndWindow = 102400 (string)
The previous two lines set both the SEND and RECEIVE windows to 100K.
These must use string as the type, or the window size will not be changed.
Hkey_Local_Machine\System\CurrentControlSet\Services\VxD\MSTCP\Parameters
SackOpts = "1" (string)
The previous line enabled SACK.
A line was not added to change the Tcp1323Opts, since it was a default
setting.
Results:
The following is the first line from a tcpdump trace of an ftp:
11:39:16.737542 windows98.1025 > netbsd.ftp: S 47053:47053(0) win 36864
<mss 1460,nop,wscale 1,nop,nop,timestamp 0 0,nop,nop,sackOK> (DF)
This line illustrates a SYN from the Windows98 machine to the NetBSD
machine. The Windows98 machine is advertising a window size of 102400.
This is derived from 36864 + wscale 1 x (65536) = 102400. It also
advertises it can use SACK.
The Internet protocols team at LeRC would be happy to work with you in the
future. We are part of the Satellite Networks and Architectures branch at
the Lewis Research Center.
.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,
Jim Griner MS: 54-2
[email protected] NASA Lewis Research Center
Phone: (216) 433-5787 21000 Brookpark Rd.
FAX: (216) 433-8705 Cleveland, OH 44135-3191
All operating systems have bugs. ...just document how it is
supposed to work and forget about the bugs.
David Greenman Core-Team/Principal Architech, The FreeBSD project
.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,
This archive was generated by hypermail 2b29 : Mon Feb 14 2000 - 16:14:35 EST