Issue with duplicate MAC enteries causing port flapping when wireless roaming

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May 9th, 2012
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I have multiple wireless access points plugged into a 3560X.  When the wireless clients begin roaming they cause duplicate MAC enteries to be created and this causes the switch ports to flap.  Is there a way to configure the switch to either ignore the duplicate MAC enteries on the switchports that have been connected to the APs or is there a way to have the ARP tables update and resolve the conflicting MAC enteries with out causing the switchport to flap?

Cisco Endorsed by jsaenzos
Sandeep Choudhary about 3 years 8 months ago

Hi Andrew,


If your APs are just bridging clients from the wireless right onto your wired network, then you're going to see this from time to time. Clients will appear from different ports as they re-associate to other APs/cells in the ESSID.


Hope it helps.

Regards

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grabonlee Thu, 05/10/2012 - 08:01
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Do you by any chance have layer 3 roaming? By this I mean do the clients roam against different subnets. Hence do they acquire IP addresses on different subnets?

Someone1234 Thu, 05/10/2012 - 10:49
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No the APs are all in the same subnet so the clients will keep the same IP address. 

Someone1234 Thu, 05/10/2012 - 10:51
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I'm looking into lowering the address ageing time but not sure this is exactly the solution that I am looking for.  This is going to cause more ARP traffic for addresses that haven't moved causing a delay in connectivity for those clients.  It's a stop gap solution I assume. 

Andrew Clark Mon, 12/02/2013 - 07:55
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were you able to resolve this? I am having a similar issue using Motorola AP's and cisco switches.

Sandeep Choudhary Mon, 12/02/2013 - 11:45
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Hi Andrew,


If your APs are just bridging clients from the wireless right onto your wired network, then you're going to see this from time to time. Clients will appear from different ports as they re-associate to other APs/cells in the ESSID.


Hope it helps.

Regards

Andrew Clark Mon, 12/02/2013 - 11:53
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Being that this is only coming from one mobile unit. I believe you may be right on that one Sandeep.

ricardocalvillo Mon, 12/15/2014 - 18:20
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Hi, could you solve it? I have Motorola AP´s and cisco switches too.

I was thinking to try with lowering the address ageing time...

Rasika Nayanajith Mon, 12/02/2013 - 11:02
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Hi Deven,


I believe your APs are in Autonomous mode. Is that correct ?


In unified wireless, roaming should be smooth & should not cause MAC flapping when user roam from one AP to another


HTH

Rasika


*** Pls rate all useful responses ****

David Watkins Tue, 12/16/2014 - 10:27
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It sounds like you're just receiving mac-move notifications, however the clients should still be operating properly.  Since these clients will be "moving", per design, you may just want to disable mac-move notifications.  This shouldn't cause "duplicate" entries.  The switch can only have a standard client Mac Address in 1 port in the CAM table at a time, otherwise you would have a loop.  Also, this shouldn't play in to ARP, because the L3 SVI should still have the same ARP (mac->IP) even when the devices shows connected through a new AP/Switchport.

Disable mac-move notifications

 

no mac address-table notification

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