W08 Cluster Validator Error: Found duplicate IP address

If you have tried installing the Windows 2008 Failover clustering one of the nice things that MSoft provides out of the box is a Cluster Validator. Not merely does it allow a more robust set of options for hardware, but it runs through a basic checklist of necessary and suggested configurations so you do not have to.

However, you may run into the following error under "Validate IP Configuration" -> Found duplicate IP address blahblahblah on node blahblah adapter Local Area Connection *blah and node blahblah2 adapter Local Area Connection *blah.

The reason for this is what is called the Teredo Tunneling Pseudo-Interface (TTPI). Which, as you can intuitively tell from its name is used to tunnel IPv6 traffic over an IPv4 interface. It turns out that the TTPI gives IDENTICAL IPv6 addresses to all the servers. Since the IP address is going through a unique IPv4 already this is not a problem (and prevents it from bumping against a different IPv6). When you apply it to clustering, however, this is flagged as an issue.

The basic solution is to disable the TTPI. The method I use is very simple:

1. Open up Server Manager to get to your Device Manager and under View select "Show hidden devices". (It is hidden, in case that was not obvious).

2. The TTPI should magically appear.

3. Now right-click and select disabled. I suggest you do this on all nodes

And you are good to go.

If this STILL does not work, take a look at Symon Perriman's entry here -> http://blogs.msdn.com/clustering/archive/2008/07/26/8773796.aspx

Have fun clustering!!!