Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base: 322756 How to back up and restore the registry in Windows
The TcpMaxDataRetransmissions registry value controls the number of times that TCP retransmits an individual data segment before it aborts the connection. This value is not configured by default, but it can be entered to change the default number of retries.
Change the following subkey in Windows 7, Windows 2008 R2, Windows 2008, Windows 2000, Windows Vista, Windows 2003, and Windows XP:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters
Value Name: TcpMaxDataRetransmissions
Data Type: REG_DWORD - Number
Valid Range: 0 - 0xFFFFFFFF
Default: 5
: This parameter controls the number of times TCP retransmits an individual data segment (non connect segment) before aborting the connection. The retransmission time-out is doubled with each successive retransmission on a connection. It is reset when responses resume. The base time-out value is dynamically determined by the measured round-trip time on the connection.
Windows provides a mechanism to control the initial retransmit time, and the retransmit time is then dynamically self-tuned. To change the initial retransmit time, modify the following registry values.
Change the following subkey in Windows 2003, Windows XP, and Windows 2000:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\ID for Adapter
Value Name: TCPInitialRtt
Data Type: REG_DWORD
Valid Range: 300-65535 (milliseconds in decimal)
Default: 0xBB8 (3000 milliseconds expressed in hexadecimal)
: This parameter controls the initial retransmission time-out that is used by TCP on each new connection. It applies to the connection request (SYN) and to the first data segments that is sent on each connection. For example, the value data of "5000 decimal" sets the initial retransmit time to five seconds.
NOTE: You can increase the value only for the initial time-out. Decreasing the value is not supported.
Change the following key in Windows NT 4.0:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\ParametersValue Name: InitialRttData Type: REG_DWORDValid Range: 0-65535 (decimal)Default: 0xBB8 (3000 decimal)
: This parameter controls the initial retransmission time-out used by TCP on each new connection. It applies to the connection request (SYN) and to the first data segment(s) sent on each connection.
For example, the value data of "5000 decimal" sets the initial retransmit time to five seconds.
The Initial RTO in Windows Server 2008 R2 and Windows 7 is can be controlled by using the NetSH command by
initialRTO.
For prerequisites and more information, click the following article number to view the article in the Microsoft Knowledge Base:
2472264 You cannot customize some TCP configurations by using the netsh command in Windows Server 2008 R2