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SetTcpWindowSize method of the Win32_NetworkAdapterConfiguration Class

Applies to: desktop apps only

The SetTcpWindowSize WMI class static method is used to set the maximum TCP Receive Window size offered by the system. The receive window specifies the number of bytes a sender can transmit without receiving an acknowledgment. In general, larger receive windows improve performance over high-delay and high-bandwidth networks. For efficiency, the receive window should be an even multiple of the TCP Maximum Segment Size (MSS).

This topic uses Managed Object Format (MOF) syntax. For more information about using this method, see Calling a Method.

Syntax

Copy

uint32 SetTcpWindowSize(
  uint16 TcpWindowSize
);

Parameters

TcpWindowSize: Maximum TCP receive window size offered by the system. The valid range of values in bytes is 0 - 65535.

Return value

Return code	Description
0	Successful completion, no reboot required.
1	Successful completion, reboot required.
64	Method not supported on this platform.
65	Unknown failure.
66	Invalid subnet mask.
67	An error occurred while processing an instance that was returned.
68	Invalid input parameter.
69	More than five gateways specified.
70	Invalid IP address.
71	Invalid gateway IP address.
72	An error occurred while accessing the registry for the requested information.
73	Invalid domain name.
74	Invalid host name.
75	No primary or secondary WINS server defined.
76	Invalid file.
77	Invalid system path.
78	File copy failed.
79	Invalid security parameter.
80	Unable to configure TCP/IP service.
81	Unable to configure DHCP service.
82	Unable to renew DHCP lease.
83	Unable to release DHCP lease.
84	IP not enabled on adapter.
85	IPX not enabled on adapter.
86	Frame or network number bounds error.
87	Invalid frame type.
88	Invalid network number.
89	Duplicate network number.
90	Parameter out of bounds.
91	Access denied.
92	Out of memory.
93	Already exists.
94	Path, file, or object not found.
95	Unable to notify service.
96	Unable to notify DNS service.
97	Interface not configurable.
98	Not all DHCP leases could be released or renewed.
100	DHCP not enabled on adapter.

Examples

For script code examples, see WMI Tasks for Scripts and Applications and the TechNet ScriptCenter Script Repository.

For C++ code examples, see WMI C++ Application Examples.

Requirements

Minimum supported client	Windows 2000 Professional
Minimum supported server	Windows 2000 Server
Namespace	\root\CIMV2
MOF	Cimwin32.mof
DLL	Cimwin32.dll

This Method and the TcpWindowSize member of this class are tied to the registry key "CurrentControlSet\\Services\\Tcpip\\Parameters|TcpWindowSize" but various MSFT documents have stated that this key is ignored in the new TCP/IP implementation that was introduced with Vista. So, in Vista in later this function just populates a registry key that's ignored by TCP/IP and MSFT apparently doesn't QA this part of Windows.

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