SW_MATM-4-MACFLAP_NOTIF due to wifi devices

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Nov 17th, 2009
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we see sometimes on a 3750switch

SW_MATM-4-MACFLAP_NOTIF: Host 000b.xxxx.xxxx in vlan 5 is

flapping between port Gi2/0/42 and port Po7

looking up the MAC we found wifi devices like a pc and handscanner which move to the building thereby changing from AP

Can it be that roaming is not properly configured as the switch sees the MAC flapping?

This is only with wifi devices, fixed servers or so are not flapping

Please help

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Overall Rating: 4 (2 ratings)
ericgarnel Fri, 11/20/2009 - 06:29
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I see these on occasion too. In our environment it is difficult to track down the end devices as they are guests and are quite temporary indeed.

My first guess would be just as you suggested,  that the devices are roaming between APs that are on different controllers and that the mobilty groups are not properly configured.  I will double check my mobility settings to verify.

Although, it misconfiguration were the issue, I would expect to see a lot more of these errors.

My second guess would be stale arp cache entries on the wired side then.....

The syslog entry is from a switch that connects the two 6505-E switches w/ wism blades

3747: Nov 20 02:29:19: %SW_MATM-4-MACFLAP_NOTIF: Host 0024.d26f.bbbb in vlan 18 is flapping between port Te0/1 and port Te0/2

ismailsh12 Fri, 11/20/2009 - 20:24
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I see the exact same error message on our Cisco 3750 switch.  I enabled LAG

since we have more than 40 AP on our controller.  Both the links of the controller are connected to the same switch as per Cisco documentation.  Below is the error I see - "Nov 20 10:13:09 EST: %SW_MATM-4-MACFLAP_NOTIF: Host 00xx.xxxx.xxxx in vlan 1 is flapping between port Gi2/0/50 and port Gi2/0/49"

BartV1982 Sun, 11/22/2009 - 21:25
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@ismail so enabling LAG didn't solve your problem?

@eric so you suggest to check the roaming and make it to always use the same controller, setup like a primary - backup (wifi is not really my field in cisco :s )

ericgarnel Mon, 11/23/2009 - 06:34
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Actually, I meant to make sure that the mobility group settings are correct.  There should be no issue of roaming between controllers. I believe he saw the issue on APs that were on the same controller, so inter-controller roaming would not be an issue.

Again, I see this issue very rarely. We will see over 20k wireless users throughout the year and I have seen it @ 5times. However, during one event, I saw the same mac address doing it quite a bit... Until I can dig up more info or duplicate it, I am going to chalk it up to client misconfiguration or cruddy wireless nic.

blankenshipgc Wed, 06/16/2010 - 16:55
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These messages can be annoying if you run a wireless network where there is a lot of roaming on a Cisco architecture such as C3750's.

Here is how to ensure the messages get completely ignored if you are tired of seeing them:

logging discriminator nolog msg-body drops flapping
logging buffered discriminator nolog
logging console discriminator nolog
logging monitor discriminator nolog
logging host X.X.X.X discriminator nolog

ahmad82pkn Sat, 09/04/2010 - 10:36
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Hey Gari, yu solved my old issue of annoying FAN messages  thanx dear.

Vinay Sharma Sun, 09/25/2011 - 11:02
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Hello Bart,

Please mark the Question as Answered, if the provided information is correct and it helped. By doing that others can take benefit as well.


Vinay Sharma

Community Manager – Wireless


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