Duplicate Client IP Address Matching Teamed Adapter on Server

Unanswered Question
Aug 17th, 2009

I am experiencing a problem with a client's WLAN and client IP address conflicts.

Basically every wireless client reports a problem that it is having an IP Address conflict with another device on the network (wired).

The device in mention is a Dell Server with Teamed network cards. They have three of them and clients are reporting conflicts with all three.

On investigating further there is no address conflict as the "Teamed Adapter" has a completly different network address (static) and the wireless clients are using the internal WLC DHCP server in a different range. (although it is all one flat network).

The clients report that there is an address conflict, the MAc that it gives is the Teamed Server but the IP address is only its own and not on the Teamed Adapter.

Has anyone seen this before or had a problem with "Teamed Adapters" on servers.

Our environment is:

WLC 4402-50 running 5.2.178

Flat Network.


I have this problem too.
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Roman Rodichev Tue, 08/18/2009 - 05:57

I've seen exactly this problem with teamed NICs but with WLC 4.x. Did you disable DHCP proxy on WLC and use the same VLAN/subnet for the servers and wireless users? If so, I think you should set up a new VLAN and dynamic interface on WLC, reenable DHCP proxy on WLC and use a separate DHCP scope for wireless users. My customer initially wanted to use one large VLAN for everything, but it created the problem you are describing. I didn't have a chance to troubleshoot why this problem was occurring, we created dedicated VLAN instead.



DigitalAirWireless Thu, 08/20/2009 - 08:36

Hi Roman,

thanks for your reply.

Basically what i have found is that it Servers running Microsoft Windows 2003 or Windows 2000, that have teamed NICs using Broadcom Advanced Server Programs (BASP) in an active/active team, respond to other server's gratuitous ARP packet with an incorrect IP address. The Microsoft Windows server will respond to the other server sending the gratuitous ARP, with the Microsoft Windows server team MAC address, but with the other server's IP address in the sender field of the packet. This causes the other system to respond as if there is a duplicate IP on the network.

Fix is to upgrade to BASP driver version 6.2.32, or newer. This version of the BASP driver was first included with the Broadcom NetXtreme Gigabit Ethernet Software.

An upgrade of the drivers apprently will fix this issue althouh i have tried it on 3 servers with this ocnfiguration and it fixed it for two of them.

The work around is to disable the active/active NIC team and use an active/standby team instead.

Someone else on this forum must of come across this before i am sure?

Anyway if it does resolve the issue i will post it back here so that anyone else in the future with this problem has a resolution!!


molinek Wed, 08/26/2009 - 06:43

Roman, we are experiencing this same issue. We have two Nexus 7010's that we just updated to 4.2.1 and it is not playing we"ll with out Dell BASP teams. Did switching to active/standy fix your issue entirely?

molinek Wed, 08/26/2009 - 08:02

Mark, where did you get this fix from? Broadcom? Dell? We have teams setup with one server in particular that is active/standby version 6.2.30 and his is putting his mac address in for other IP's on our nexus core switches. We are going to try to simply update the drivers to the latest and see. For now we have had to enter static arps for these server that are getting their mac's over written with invalid macs.


DigitalAirWireless Wed, 08/26/2009 - 12:55

I got the latest drives from the dell website for my particular adapter, they were also available from the Braodcom site as well but it recommended that i went to Dell.


molinek Thu, 08/27/2009 - 08:09

So can you run a team in load balance or just a team in active/standby with the new drivers?


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