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P2_WARN: 1/Host <mac_address> is flapping between ports <mod#>/<mod#>

We have 4 stackable Cat-2980G switches that uplink (Etherchannel) and downlink (Etherchannel)to a pair of Cat-6506's. The Cat-6506's have MSFC's. The error message in the syslog on the first Cat-2980G switch says the following:" P2_WARN: 1/Host 00:07:b3:48:cf:fc is flapping between ports 3/22 and port 3/33". The port 3/33 is an uplink port to one of the Cat-6506's. When I did "sh cam dynamic" on both ports, the 3/22 port did not have that MAC address on it, however the 3/33 did. So, I traced it down to the MSFC port (15/1)on the Cat-6506 switch. This is the right path for traffic to take for switching VLAN's. What I can't figure out is why is the error message saying that the that MAC address was learned from the 3/22 port, when it was really learned from port 3/33. Can anybody please help?


Cisco Employee

Re: P2_WARN: 1/Host <mac_address> is flapping between ports <mod

You might be having STP issues. The following page should help


Re: P2_WARN: 1/Host <mac_address> is flapping between ports <mod

I have also seen these type issues when the switch is flaking out . Sometimes a reload will help , other times we have seen where it is a supervisor going south .

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