Duplicate IP Address Detected

[nick_furnell]

Has anyone seen these error messages before? We started seeing these e-mails after upgrading our CS220G to the 2.1.4 Firmware BUT we also installed a pair of Brocade Switches within a very short period of time. So it's a little hard to tell which is causing the issue, although we checked the Brocade logs for IP/MAC address clashes and didn't find anything. Are there any logs on the Nimble that may help?  We generally see these messages when the Nimble is under load eg. Backup Job running

Again this may be a red herring. I am interested in anyone's thoughts.

Type: 12212

Id: 22675

Message: A duplicate of IP address 192.168.10.20 is found in the network.

Group Name: Pines-Nimble

Group ID: 8319827154462659106

Array name: Pines-Nimble

Serial: AC-xxxx

Version: 2.1.4.0-100755-opt

Arrays in the group:

---------------------+-----------------+-----------+----------------+-----------

Name                  Serial            Model       Version          Status

---------------------+-----------------+-----------+----------------+-----------

Pines-Nimble          AC-xxx         CS220G-X4   2.1.4.0-100755-opt reachable 

[mlucas57]

Hello Nick.  I recently observed this exact same scenario.  You might start by clearing the ARP cache on the switches then double check your VLAN membership on the ports where the Nimble array connects (assuming you have multiple VLANs in play).  In this customer’s environment a couple of the switch ports were in the wrong VLAN which lead to the duplicate IP message appearing within the Nimble GUI.

[ageiger3171]

I would also check the port configs to ensure that "spanning-tree portfast" is enabled on all access ports for the Nimble array.  We ran into an issue where the array threw a potential failover error when the ports were not configured with this option.

[jwhyte119]

Hey Nick,

Another thing to check for is a feature called Proxy ARP.  This allows a host to cache an ARP entry and respond to ARP requests on behalf of another host.

Please let us know if you have seen this error again recently, or if you have managed to find a resolution.

Cheers,

John

[nick_furnell · Accepted solution]

Thanks Guys

We have checked the Switches for any ARP Cache errors and also for VLAN assignments - no look there.

To help identify the problem (or create a new one), I also upgraded the Firmware on a second Nimble to 2.1.4 - this site also has exactly the same Brocade switch settings, so far no Duplicate IP errors. The only difference is that the Nimble with the errors is an upgraded CS220, whereas the other Nimble is a CS240G.

So far we haven't seen any new Duplicate IP errors for over a week? Maybe it's just one of those things...