error Cisco 3750G Port, vlan on PO# flapping - PO disconnected at the other end. same number PO at both ends

[m-abooali]

Hello folks,

I have a port-channel po20 connecting a stack of 3 switch Cisco 3750G to an aggregate Switch stack of 3 Cisco 375012-s-s.

I see these errors on port flapping:

xxx-ACCS-SW01#
Oct  4 14:35:04.270: %SW_MATM-4-MACFLAP_NOTIF: Host 3464.a9d3.3124 in vlan 224 is flapping between port Po20 and port Gi1/0/1
CUP-ACCS-SW01#sh run int gi1/0/
Oct  4 14:35:38.479: %SW_MATM-4-MACFLAP_NOTIF: Host 3464.a9d3.3124 in vlan 224 is flapping between port Po20 and port Gi1/0/125

Po # is same at both ends and interfaces are connected to port channel the right way. vlan 224 is the management vlan. another engineer has created few SVIs on the aggregate Stack that in my opinion all mus be on core only and only vlan 224 shroud be on the aggregate switch as well as the node switch where i see those error listed above.

the Port-channel is disconnected on the aggregate or distribution stack but still active on the node stack. one link gone dark and stack is operational on one link.

Your thoughts on this and possible solutions would be greatly appreciated. old community Solved flapping cases points to PO # being different at at both ends where its not in this case. Seema that PO is flapping between different MAC addresses!?

Best Regards,

Masood

[balaji.bandi]

what is this device ? Host 3464.a9d3.3124 ?

[m-abooali]

hi,

I believe it was an IP phone. the vlan Ip on this node was wrong but that did not cause the issue. I changed fiber port at the distribution sw and that fixed the problem!?

port channeldoesn't get shut any more and both links stay up!. I am still thinking how a bad fiber port on Cisco 375012-s-s could cause this error!?

I moved connection on distribution sw from gi 1/0/12 to gi1/0/11 and all worked well.

i am still trying to understand what happened really!?

Thank you for responding and I would appreciate any insight based on the info I just provided please.

Best Regards,

Masood