UCS - False duplicate IP address detected on Microsoft Windows Vista and later virtual machines on ESX/ESXi when using Cisco devices on the environment

Symptoms

• When you assign an IP address on Windows Vista and later versions, you see a duplicate IP address conflict.
• When you restart Windows Vista and later versions, you receive a 169.254.x.x IP.
• When you set up the same virtual machine on a vSwitch with no uplink port on the vSwitch, the IP address is assigned successfully.
• When you assign the same IP address to a Windows 2003 virtual machine on the same vSwitch, the IP address is assigned successfully.

Cause

This issue occurs when the Cisco switch has gratuitous ARPs enabled or the ArpProxySvc replied to all ARP requests incorrectly.

Resolution

Note: The information provided in this article is a workaround. Investigate the network configuration at the physical layer for the root cause. For more information regarding this topic from Cisco please see Duplicate IP Address 0.0.0.0 Error Message Troubleshoot

To work around this issue, turn off gratuitous ARP in the guest operating system.

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. For more information on backing up and restoring the registry, see the Microsoft article 136393.

Note: The preceding link was correct as of April 24, 2014. If you find the link is broken, provide feedback and a VMware employee will update the link. 

To turn off gratuitous ARP in the guest operating system:

1. Shut down the guest operating system and power off the virtual machine.
2. Change the virtual machine to a network vSwitch with no uplink. You can create one for this procedure.
3. Power on the virtual machine and log in.
4. Open the Registry editor.
   
   • In Windows XP to Windows Server 2003 - Click Start > Run, type regedit, and click OK.
   • In Windows 7 and Current - Click Start, type regedit, and click OK.
5. Locate this registry key:
   
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
6. Click Edit > New, and click DWORD Value.
7. Type ArpRetryCount.
8. Right-click the ArpRetryCount registry entry and click Modify.
9. In the Value box, type 0 and click OK.
10. Exit the Registry Editor.
11. Shut down the guest operating system and power off the virtual machine.
12. Change the virtual machine back to a network vSwitch with the uplink.
13. Power on the virtual machine.

Alternatively, you can disable gratuitous ARP on the physical switch.

For example:

To disable gratuitous ARP in Cisco IOS, run this command:


# no ip gratuitous-arpshttp://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1028373

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