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New Member

MEC is not working with LACP in between VSS & Cross stack wise switches

Hi Experts,


trying to establish MEC between VSS & two different stack members in stackwise ( master and one of stack member ).

I gone through cisco document where I understood that PAGP would not support in this scenario ( BFD would not work ) because of cross stackwise connection from VSS therefore LACP is recommanded  however I have configured the same and its not coming up.


when  I see logs in my stackwise switch , I see log as below :


" MACFLAP-NOTIF " mac address xx.xx.xx.xx.xx.xx ( VSS vlan mac address ) is flapping between 2/0/48 ( one of the port in LAG ) and po01 ( same portchannel which configured between VSS & stackwise switch )



Can anybody suggest me on this what could be the cause for this error ?







VIP Super Bronze

Hi,Can you post the configs


Can you post the configs for these ports and vlans from both VSS and the stack switches.

What if you try to establish MEC using only one switch and not stack?


New Member

Hi , Thanks for your reply. .

Hi ,


Thanks for your reply. .....

I would share the config shortly however just to confirm that , If you establish MEC with only one switch in stack , It works fine....



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