Optimizing Windows Networking

dt logo 1.5inchWhen using Drastic software on Windows, for some operations the network settings must be altered to allow for the performance necessary for the workflow. This includes Net-X-Code for UDP/RTP/RTSP streams, SMPTE 2022-6, and SMPTE 2110 streams, and any other workflow that requires high throughput from the Windows network stack.

Optimizing Windows Network


DWORD: DefaultSendWindow

DWORD: DefaultReceiveWindow

Key:  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\AFD\Parameters

Set the value to 0x10000 in both cases.

"DefaultSendWindow", "DefaultReceiveWindow" control TCP window size


DWORD: MaximumReassemblyHeaders

Key:  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters

Set the value to 0xffff (this is the max value)

Source:  http://support.microsoft.com/kb/811003


DWORD: FastSendDatagramThreshold

Key:  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\AFD\Parameters

Set the value to 0x10000 (if you have 64k Jumbo frames available)

Set the value to 1500 (if you are using a traditional network)

Source:  http://support.microsoft.com/kb/235257


DWORD: TcpWindowSize


Set the value to 0x100000

"TcpWindowSize" controls the TCP window size




Set the value to 1

cp1323Opts - allows the scaling of the TCP window above 16k.

Source: http://technet.microsoft.com/en-us/library/cc938205.aspx


Disable Windows Scaling heuristics

netsh int tcp set heuristics wsh=disabled forcews=enabled

The wsh tag is legacy.  The fourcews can be set to enabled or disabled.


TCP Auto Tuning

netsh int tcp set global autotuninglevel=disabled

The default is 'normal'.  Other possible settings include:

disabled: uses a fixed value for the tcp receive window. Limits it to 64KB.
highlyrestricted: allows the receive window to grow beyond its default value, very conservatively.
restricted: somewhat restricted growth of the tcp receive window beyond its default value.
normal: default value, allows the receive window to grow to accommodate most conditions.
experimental: allows the receive window to grow to accommodate extreme scenarios (It enables RWIN values of over 16 MB).


Enable Connnection Rate Limiting

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\Tcpip\Parameters] “EnableConnectionRateLimiting”=dword:00000000

Removes rate limiting of connections in Windows 7, 8, and 10

Cached Logons Count

[HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon]


Change CachedLogonsCount to 50 (the max) or 0 (disabled)