Enhanced vPC order of operations

When configuring an enhanced vPC for the following topology; 

server homed across 2 fexes.

dual homed fexes. 

what is the correct order of operation for the server facing fex ports and port channel?

(the fexes have already been associated with the parent 5ks, via a vPC) 

I ask this because I hit upon an error when attempting this for the first time, and I am not sure what it means.

command failed: port not compatible [vPC cannot be defined across more than 2 FEXes ]



  • First off make sure that you are not using unsupported eVPC topology




    As for order of operations it should be the following


    1) N5Ks VPC peering is UP

    2) Fexes are online and connected via VPC to its parent N5Ks ( Note FEXes don't support LACP, so unconditional port-channel mode ON should be configured on ports connecting to them)

    3) If using FCoE define one FEX per parent switch that will be doing FCoE. So if you have FEX1 and FEX2 and N5K1 and N5K2 lets say, on N5K1 define FEX1 as fcoe capable, and on N5K2 define FEX2 as fcoe capable.


    4) once it is one define port-channel connecting to host. Note you don't need to declare host facing ports as VPC, since it is going to be VPC automatically. You have defined as VPC port connecting to your FEXes above. And FEX is just a remote line card meaning that all of its ports are VPC enabled by default.




  • I take it you are seeing this error when using INE racks?

    If so, this is a hardware limitation of the 5010/5020 switches.

    The 5548 switches do not have this limitation, however only rack 8 has the 5548's.

    For the server config on your Fex ports, just remove the port-channel command and it should work fine.

    I hit this issue a few months back.

    Try booking a lab and specifically asking for rack 8, then you can do your EvPC with port-channels no problem.

    In a nutshell, it's not an order of ops issue, it is hardware.

  • Dominic, thanks for you reply.

    Yes this was on the INE rack.

    I suspected there was a hardware related reason, although when i looked at the associated documentation i could only find reference to the version of NX-OS that supported enhanced vPC, not the hardware, although i am new to using the cisco documentation I am going to say my inability to find feature vs. hardware was my error.   

    I suppose Rack 8 is going to be seeing a lot of action in the future...

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