You cannot customize some TCP configurations by using the netsh command in Windows Server 2008 R2

After you install this hotfix, you can configure the following TCP configurations by using the netsh command:

Configuration 1: Initial RTO

• netsh interface tcp set global <for help>
• netsh interface tcp set global initialRto=<value in msec>
• netsh interface tcp show global
  
  Note This command displays the values that are set.

Warning : Setting a low value of Initial RTO could result in failure to connect.

Minimum value for initialRto (Retransmit timeout) is 300 ms, maximum is 3000 ms (3 seconds, to meet RFC 1122)

The registry key TcpMaxConnectRetransmissions is no more supported since Windows Server 2008 / Windows Vista.



Configuration 2: MinRto, ICW and DelayedAckTimeout

Windows Server 2008 R2 and Windows 7 operating systems provide two kinds of templates: Internet and Custom. You can customize values by using the Custom template. The Internet template is read-only.

• netsh interface tcp set supplemental <for help>
• netsh interface tcp show supplemental
  
  Note This command displays the template values.

The value of delayedacktimeout on the receiving machine needs to be lesser than the value of MinRto on the sender to avoid unnecessary retransmissions. The default value of delayedacktimeout is 200ms and MinRto is 300ms.


For example, you can use the following command to set the values for the Custom template.

netsh interface tcp set supplemental template=custom minRto=20 icw=16 delayedacktimeout=10

Note You have to tell the stack to use these Custom template values. The default template that the stack uses is the Internet template. To do this, use one of the following methods:

• Add a port-based filter by using the following command:
  
  netsh interface tcp add supplementalport
  Note Command Help shows an example.
• Add a subnet-based filter by using the following command:
  
  netsh interface tcp add supplementalsubnet
  Note Command Help shows an example.
• Set the Custom template to be the global default template by using the following command:
  
  netsh interface tcp set supplemental template=custom
  Note This command makes the custom values valid for all connections.

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing the problem described in this article. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft website:

http://support.microsoft.com/contactus/?ws=support

Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Prerequisites

To apply this hotfix, you must be running one of the following operating systems:

• Windows Server 2008 R2
• Windows Server 2008 R2 Service Pack 1 (SP1)

Registry information

To use the hotfix in this package, you do not have to make any changes to the registry.

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace a previously released hotfix.

File information

The global version of this hotfix installs files that have the attributes that are listed in the following tables. The dates and the times for these files are listed in Coordinated Universal Time (UTC). The dates and the times for these files on your local computer are displayed in your local time together with your current daylight saving time (DST) bias. Additionally, the dates and the times may change when you perform certain operations on the files.

Windows 7 and Windows Server 2008 R2 file information notes

Important Windows 7 hotfixes and Windows Server 2008 R2 hotfixes are included in the same packages. However, hotfixes on the Hotfix Request page are listed under both operating systems. To request the hotfix package that applies to one or both operating systems, select the hotfix that is listed under "Windows 7/Windows Server 2008 R2" on the page. Always refer to the "Applies To" section in articles to determine the actual operating system that each hotfix applies to.

• The files that apply to a specific product, milestone (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table:

  Version	Product	Milestone	Service branch
  6.1.760 0.20xxx	Windows 7 and Windows Server 2008 R2	RTM	LDR
  6.1.760 1.21xxx	Windows 7 and Windows Server 2008 R2	SP1	LDR

• The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed separately in the "Additional file information for Windows Server 2008 R2 and for Windows 7" section. MUM and MANIFEST files, and the associated security catalog (.cat) files, are extremely important to maintain the state of the updated components. The security catalog files, for which the attributes are not listed, are signed with a Microsoft digital signature.

For all supported x64-based versions of Windows Server 2008 R2

For all supported IA-64-based versions of Windows Server 2008 R2