FEX and vpc peer-link failure


Let's assume a fex straight throught topology with a host vPC dual homed to 2 fex. Each of these fex is connected to one vPC peer (5k or 7k doesn't probably matter). What happens to the fex HIF of the secondary vPC peer in the event of a peer-link failure. I have read that the fex is brought down on the secondary vPC (as for vPC related SVI and members). However for me the fex uplinks look like orphaned ports in a straight through topology (whether pinning or port-channel is used), so would you need to use "vpc orphan-port suspend" to get this behaviour or is it "native"?

Thanks for any clarification




  • When VPC peer-link fails but keepalive link is still active secondary VPC peer device shuts down its member ports.

    Fex uplink port remains UP, since FEX is not connected with VPC to peers.

    This is default behaviour, so nothing needs to be configured.


  • http://www.cisco.com/en/US/prod/collateral/switches/ps9441/ps9670/C07-572829-01_Design_N5K_N2K_vPC_DG.pdf

    This document is telling the opposite, cf p43 and also on fig 14:

    "Upon failure of the peer link, the vPC secondary switch checks whether the vPC primary switch is still alive (by
    using the heartbeat verification mechanism of the peer keepalive link) and correctly shuts down the vPC member
    port on the secondary Cisco Nexus 5000 Series Switch and associated Cisco Nexus 2000 Series Fabric

    This is for straight through configuration so no vPC for fex ports.

    Don't know what to think about this :-)


  • i guess i've written the same to you. 

    ports from 5K to 2K are regular port channels. They remain UP. 

    Only members ports, the ones that are connected to servers will be down.


  • You wrote the same as what I did think, that is the opposite of the document (i.e the FEX ports stay UP while the document states that they will be DOWN on the secondary peer)

    So now I'm quite sure that the document is wrong or the author assumes "vpc orphan-port suspend" to avoid a dual active state when a server is dual homed to 2 fex connected with standard port-channels.

    Thanks for helping out.

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