Poor network performance on Windows 2008 Server virtual machine

Products

• VMware vCenter Server
• VMware vSphere ESXi

Issue/Introduction

Symptoms:
A virtual machine running a Windows 2008 Server may experience these symptoms:

• Poor network performance
• Slow network transfers

Environment

VMware vSphere ESXi 5.1
VMware ESX 4.0.x
VMware vSphere ESXi 5.0
VMware ESX 4.1.x
VMware vCenter Server 5.0.x
VMware ESX Server 3.5.x
VMware vCenter Server 4.1.x
VMware vSphere ESXi 5.5
VMware vCenter Server 5.1.x
VMware vCenter Server 5.5.x
VMware vCenter Server 4.0.x

Resolution

To resolve this issue, ensure that the virtual machine uses an Intel e1000 driver or enhanced vmxnet or vmxnet3 driver (depending on the ESXi/ESX version support) for the virtual network card. Also, ensure to disable TCP segmentation Offload (TSO).

 

To disable TSO:

 

Note: This procedure modifies the Windows registry. Before making any registry modifications, ensure that you have a current and valid backup of the registry and the virtual machine.

 

The preceding link was correct as of November 27, 2013. If you find the link is broken, provide feedback and a VMware employee will update the link.

1. Click Start > Run, type regedit, and click OK. The Registry Editor Window opens.
2. Navigate to the HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\ registry key.
3. If the key does not exist select Edit > New > DWORD (32-bit Value).
4. Type DisableTaskOffload for the name of the key and press Enter to save the changes.
5. Right-click the DisableTaskOffload key and click Modify.
6. Change the value data to 1.
7. Click OK to accept the changes.

To disable TCP Segmentation Offloading in Windows 2008:

1. <run <br="" the="">Run this command:
   
   netsh int tcp set global chimney=disabled
   
   </run>
2. Reboot the virtual machine.

Note: The provided registry value only changes one of many parameters, while the above command updates all the necessary parameters.

Additional Information

For more information about:

• IPv6, see Configuring IPv6 with Windows Vista
• Windows 2008 Server kernel changes, see Inside Windows Server 2008 Kernel Changes
• Disabling TaskOffload, see Inside Windows Server 2008 Kernel Changes
• TCP Chimney Offload, see the Microsoft Knowledge Base article 951037
• Disabling IPv6, see How to disable IPv6 or its components in Windows

Note: The preceding links were correct as of November 21, 2013. If you find a link is broken, provide feedback and a VMware employee will update the link.

Windows 2008 Server 仮想マシンのネットワーク パフォーマンスの低下
Windows 2008 Server 虚拟机上的网络性能低下