Failover Cluster Validation Report failed for Duplicate IP address Windows 2008

Cluster validation wizard is used to check pre-requisite\best practices before building the cluster. While playing with my lab, I came across a issue under Network Test.

Error:
Found duplicate IP address fe80::100:7f:fffe%14 on node node1.vodka.com adapter Local Area Connection* X and node node2.vodka.com adapter Local Area Connection* X.

Resolution:
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
c. Teredo will now be 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

But what about disabling Teredo through Device Manager?  This will only disable the Teredo adapter so the system does not see it anymore, however this does not disable the underlying logic.  This could cause issues later, so it is recommended to disable it through the command line or the registry.

Run Validate and this test will now pass. Enjoy your fully supported cluster!

Don’t forget to leave your valuable comments.

Thanks,
Aresh

Useful Blogs:
Microsoft’s Failover and Network Load Balancing Clustering Team Blog: http://blogs.msdn.com/clustering/