Hi all, Windows 2003 server which hosts sql2005 and windows 7 clients we found out the sql app runs very slow over WAN. As I googled, some mention we need to change TCPWindowSize through registry. which value should I set for TCPWindowSize? 1,073,725,440 bytes HKLM\System\CurrentControlSet\Services\Tcpip\Parameters ? should i just change it on the windows 2003 server, not windows 7 client? Do I need to add this key too? HKLM\System\CurrentControlSet\Services\Tcpip\Parameters\Tcp1323Opts registry value to 1 or 3. Can anyone help?

anyone from Microsoft? Thank you.

Hi, Thank you for the post. 1. The Windows registry key TCPWindowSize default value is 17520 and Tcp1323Opts is 3 (Timestamps and window scaling are enabled). http://technet.microsoft.com/en-us/library/cc757802(WS.10).aspx http://technet.microsoft.com/en-us/library/cc757402(WS.10).aspx 2. I suggest you set TCPWindowSize value to 65535 first. If you want to set value over 65535 (like 1,073,725,440), you need keep Tcp1323Opts value to 1 or 3. (no need to add the key if it does not exist) http://support.microsoft.com/kb/224829 3. The TCPWindowSize function require both traffic sides specified or one side enable Auto-Tuning feature. So just need to change the registry key on server end and Auto-Tuning is enabled on vista based client by default. http://technet.microsoft.com/en-us/magazine/2007.01.cableguy.aspx http://blogs.msdn.com/b/wndp/archive/2007/07/05/receive-window-auto-tuning-on-vista.aspx 4. The TCPWindowSize registry require computer reboot to take effect. If there are more inquiries on this issue, please feel free to let us know. RegardsRick Tan TechNet Community Support

Hi, Thank you for the post. 1. The Windows registry key TCPWindowSize default value is 17520 and Tcp1323Opts is 3 (Timestamps and window scaling are enabled). http://technet.microsoft.com/en-us/library/cc757802(WS.10).aspx http://technet.microsoft.com/en-us/library/cc757402(WS.10).aspx 2. I suggest you set TCPWindowSize value to 65535 first. If you want to set value over 65535 (like 1,073,725,440), you need keep Tcp1323Opts value to 1 or 3. (no need to add the key if it does not exist) http://support.microsoft.com/kb/224829 3. The TCPWindowSize function require both traffic sides specified or one side enable Auto-Tuning feature. So just need to change the registry key on server end and Auto-Tuning is enabled on vista based client by default. http://technet.microsoft.com/en-us/magazine/2007.01.cableguy.aspx http://blogs.msdn.com/b/wndp/archive/2007/07/05/receive-window-auto-tuning-on-vista.aspx 4. The TCPWindowSize registry require computer reboot to take effect. If there are more inquiries on this issue, please feel free to let us know. RegardsRick Tan TechNet Community Support

>I suggest you set TCPWindowSize value to 65535 first Is (TCPWindowSize value to 65535) the default value? Thank you for your help.

Hi, Is (TCPWindowSize value to 65535) the default value? No, the TCPWindowSize default value is 17520. RegardsRick Tan TechNet Community Support