Further Information on DefaultSendWindow
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Appendix C: Windows Sockets and DNS Registry Parameters
Appendix C: Windows Sockets and DNS Registry Parameters
Updated: July 6, 2005
AFD Registry Parameters
Afd.sys is the kernel-mode driver that is used to support Windows Sockets applications. When there are three default values, the default is calculated based on the amount of memory detected in the system:
* The first value is the default for smaller computers (less than 19 MB).
* The second value is the default for medium computers (<32 MB on Windows XP Professional, <64 MB on Windows Server 2003).
* The third value is the default for large computers (>32 MB on Windows XP Professional, >64 MB on Windows Server 2003).
For example, if the default is given as 0/2/10, a system containing 12.5 to 20 MB of RAM would default to 2.
The following values can be set under:
HKEY_LOCAL_MACHINE
\SYSTEM
\CurrentControlSet
\Services
\Afd
\Parameters
DefaultReceiveWindow
Value Type: REG_DWORD
Default: 4096/8192/8192
Description: The number of receive bytes that AFD buffers on a connection before imposing flow control. For some applications, a larger value here gives slightly better performance at the expense of increased resource utilization. Applications can modify this value on a per-socket basis with the SO_RCVBUF socket option.
DefaultSendWindow
Value Type: REG_DWORD
Default: 4096/8192/8192
Description: This is similar to DefaultReceiveWindow, but for the send side of connections.