mac flapping error messages

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  • Idea
  • Updated 2 years ago
Not really an Idea, more of a sharing of info

I see these messages on my cisco catalysts quite a bit

%SW_MATM-4-MACFLAP_NOTIF: Host xxxx.xxxx.xxxx in vlan 50 is flapping between port Gi1/0/4 and port Po10


is flapping between port Gi1/0/1 and port Gi1/0/3

At this point I suspect that it is clients roaming or not roaming but moving about the building from AP to AP on same switch or from AP to AP on another switch

anyway if you want to ignore these messages

use these commands on cisco switches, 3850 and 3750's

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
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Andrew MacTaggart, Champ

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Posted 5 years ago

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Photo of intvlan1shut


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I'd sure like to know why I'm getting a ton of these msgs too. I appreciate the tip for ignoring the msgs on the switch but I'm still really wanting to know what/why I get so many of them and what if anything can be done to correct it.


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Andrew MacTaggart, Champ

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It's because user traffic is terminated at the AP and not tunneled back to a controller. The Switch sees a client mac address on port A then client roams to a different AP and the mac address shows up on a different port, say port B. New IOS code seems to think this is a security violation of some sort.
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Eric Rabuse

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I was just about to post this question about the flap, flap, flapping,but it looks like you guys are on the ball. Thanks !

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M. Boekholt

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Does anyone have experiensed flapping errors across core-switches (Cisco 3750/3850s)/Layer 3 switches out of the blue? That means, there can be times that no flapping apears over our Layer 3 switches (only our layer 2 between AP's as designed) and then suddenly the Layer 3 switches behind the access switches (layer2) start giving flapping between several organisations per second and making the layer 3 switch almost hang themselfs with CPUs of 98/99%