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vlan 2 is flapping between port

I have checked the log that the switch show

(core switch)

001293: Sep 22 09:47:02: %SW_MATM-4-MACFLAP_NOTIF: Host f49f.5474.d214 in vlan 2
is flapping between port Gi1/0/9 and port Gi1/0/12


(L3 switch that connect by trunk with core switch)

000635: Sep 23 05:24:16: %SW_MATM-4-MACFLAP_NOTIF: Host 0025.4654.a6c1 in vlan 2
is flapping between port Gi1/0/1 and port Gi1/0/9

What is the cause of it? How can I check it? does it contain a switching loop?

please help


Re: vlan 2 is flapping between port

I think this question would fit better in the LAN, Switching and Routing, than WAN section. Skipping this personal opinion, you gave us to less details to really be able to give you one solution. I can assume from your output that the core switch connect to the other switch over interface Gi1/0/9 (on both switches). What about other 2 interfaces in these switches? Gi1/0/1 and Gi1/0/12, where are these ports connected?

If you have there a typical redundant connections (triangle or square topology) than you might have a loop. Check if you have any logs regarding spanning-tree or interface flapping, that could cause loops.