Cluster Validate Error for Duplicate IP Addresses? Teredo may be the Culprit!

Hi Cluster Fans,

We’ve been seeing an increasing number of questions about a specific error in Windows Server 2008 Failover Clustering using the ‘Validate a Configuration’ Wizard (‘Validate’).  This error is fairly common and very easy to fix and I’m going to show you how.  But first, a little background…

Validate is our new built-in functional test tool for Failover Clustering.  It can be run before you create your cluster, during creation or even during production where it functions as a diagnostics and troubleshooting tool.  Passing all Validate tests is required for support, as described in our support policy: http://support.microsoft.com/kb/943984. 

However some of you are failing Validate with the following error:

Verifying that there are no duplicate IP addresses between any pair of nodes.

Found duplicate IP address fe80::100:7f:fffe%13 on node node1.contoso.com adapter Local Area Connection* X and node node2.contoso.com adapter Local Area Connection* X.

It turns out that this is the result of the Teredo, an IPv6 Tunneling Protocol.  Teredo allows IPv6 communications to pass through IPv4 NATs and IPv4 servers.  However Teredo gives an identical IPv6 address to its network interfaces, which Failover Clustering flags as an error since it require unique IP addresses.

So how do you fix this?  There are 2 ways, some details are provided here: http://technet2.microsoft.com/WindowsVista/en/library/91d35c9f-3049-44f4-b711-743dc152c7c31033.mspx?mfr=true

1)      Disable Teredo through command line

a.       Open ‘Command Prompt’ and ‘Run as Administrator’

b.      Type:

                                                              i.      > netsh

                                                            ii.      > interface

                                                          iii.      > teredo

                                                           iv.      > set state disabled

2)      Disable Teredo through the registry

a.       Open the Registry Editor

                                                              i.      This can be done through an elevated Command Prompt and typing ‘regedit’

b.      Navigate to: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip6

c.       Right-click on the ‘Parameters’ tab, select ‘New’, choose ‘DWORD’

                                                              i.      Enter the following name (including capitalization): “DisabledComponents”

d.      Double-click on “DisabledComponents”, select ‘Hexadecimal’, under ‘Value data’

                                                              i.      Enter “8”

e.      Click ‘OK’

f.        Restart your machine

g.       Teredo will now be disabled