Knowledge Base

This error is seen because the VMware virtual bridge can operate at any speed and is constrained only by the processing power of the host computer's processor. When traffic is sent from the guest to the host it can be sent at very fast speeds.  Windows Server 2003 includes security features that interpret network requests at speeds above a specified limit as denial of service attacks. In response, Windows Server 2003 disconnects the client — in this case, the guest VM.  Once it is disconnected Windows will not allow it to connect again.

There are several ways you can avoid such disconnections. Use the one that is most convenient in your environment.

• Use the bandwidth limiting feature of VMware Workstation 5 (this workaround does not apply to GSX Server). Using a text editor, add two lines to the configuration (.vmx) file of the affected virtual machine.

  If the physical Ethernet adapter on the host computer is running at 100Mbps, use the following two lines:
  ethernet0.txbw.limit=100000
  ethernet0.rxbw.limit=100000

  If the physical Ethernet adapter on the host computer is running at 10Mbps, use the following two lines:
  ethernet0.txbw.limit=10000
  ethernet0.rxbw.limit=10000

  In both examples above, the setting affects the virtual machine's first virtual Ethernet adapter (ethernet0). To modify the setting for a second virtual Ethernet adapter, substitute ethernet1. For a third virtual Ethernet adapter, use ethernet2.

  This approach increases the load on the host computer's processor and may affect performance.

• Disable large send offload in the network settings for the physical Ethernet adapter on the host computer. Note: This is host operating system dependent, not a VMware setting.

  This approach increases the load on the host computer's processor and may affect performance.

• Use a gigabit switch. Connecting the host computer's network adapter to a gigabit switch helps because the bridge cannot produce traffic that exceeds the 1000Mbps speed of the switch. This workaround provides the highest throughput when you copy large files.

• Change the configuration of the virtual machine to use host-only networking. This change is simple to make and may be appropriate for some virtual machines.

• Disable or change the Windows Server 2003 settings on the host to disable the security feature.  Note: this may increase the security risk of the host as it affects connections to external hosts as well.  See: http://support.microsoft.com/kb/898468 for instructions on how to do this.