Hi,When observing Wireshark captures of Vista's FTP.exe downloading a 10MB files, I see the TCP receive window size at the FTP.exe side sometimes increases from 16K to 64K. This usually happens about 1 second after the 3-way handshake. It's not always reproduced but I have about 50% success rate on 10M NIC. This is not seen on XP. First I thought this is caused by Vista's "TCP Receive Window Autotuning", however, setting autotuning to disbale, reboot, and I can still see this.My questions are: 1. What causes the RWIN size change? Is there any way to configure the initial size? Any document ? 2. How do I make FTP.EXE start at 64K window size like FileZilla FTP client does? I tried -r -x -w parameter but does not work.Any help are appreciated.peter.

Hi, Regarding the #1, Windows Vista made tremendous improvements on TCP/IP, other features may affect Receive Window. Hope the following articles can help you: Advances in Windows Vista TCP/IP http://blogs.msdn.com/wndp/archive/2006/05/05/Winhec-blog-tcpip-2.aspx Receive Window Auto-Tuning on Vista. http://blogs.msdn.com/wndp/archive/2007/07/05/receive-window-auto-tuning-on-vista.aspx TCP Receive Window Auto-Tuning http://technet.microsoft.com/en-us/magazine/cc162519.aspx Regarding the #2, based on my knowledge, we cannot set FTP.EXE start at 64K window size. Thanks.