W2K8 R2 – Network Optimisations For VMware Guests

W2K8 R2 – Network Optimisations For VMware Guests

This article provides several networking optimisations for a Windows 2008 R2 Virtual Machine.

The following sections provide details on different settings which can be modified for both the Operating System and the VMXNET 3 network driver.

Disabling IPv6

If you have no need for IPv6 on your network then disabling it will cut down on unnecessary network traffic.  IPv6 can be disabled either through the registry as shown below or through the Network Card Properties :-

reg add hklm\system\currentcontrolset\services\tcpip6\parameters /v DisabledComponents /t REG_DWORD /d 255

Adding the registry key above disables IPv6 for all adapters on the server.  If you only want to disable it for certain adapters you will need to disable it through the Network Card Properties as shown below :-

  • Go to the Network and Sharing Centre either through the Control Panel or by Right Clicking the Network icon in the Systray
  • Select Change Adapter Settings in the Top Left of the screen
  • Right Click on the Adapter you wish to disable IPv6 on and selectProperties.
  • Untick the Internet Protocol Version 6 (TCP/IPv6).
  • Click on OK to save the setting

Disable TCP Chimneying

TCP Chimneying or TCP Offload is designed to transfer the network load  from the CPU’s to the network adapter.  There have been various reports of slow networking on Windows 2008 R2 virtual machines and long transfer times of files across the network and many people disable this technology.  To disable TCP Chimneying on a server perform the following steps :-

  • Right Click on the Command Prompt icon in the Start Menu and selectRun as Administrator and if necessary authenticate when prompted.
  • In the Command Prompt execute the following :-

netsh int tcp set global chimney = disabled

  • The command will return Ok. when executed

A reboot is required in order to implement the change.

Disable TCP Autotuning

There have been various reports of slow networking on Windows 2008 R2 virtual machines and long transfer times of files across the network and many people disable this technology.  To disable TCP Autotuning on a server perform the following steps :-

  • Right Click on the Command Prompt icon in the Start Menu and selectRun as Administrator and if necessary authenticate when prompted.
  • In the Command Prompt execute the following :-

netsh int tcp set global autotuninglevel = disabled

  • The command will return Ok. when executed

A reboot is required in order to implement the change.