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Virtual Connect Flex 10 and CISCO Nexus virtual switches

Trusted Contributor

Virtual Connect Flex 10 and CISCO Nexus virtual switches

A pretty detailed question from Nick:




Hi All,


I have a customer who has 8 x c7000 chassis connected to 2 Nexus switches (acting as a single virtual switch).


In my experience we have always had each VC module connecting to a single physical switch, but the customer wanted to connect in a mesh. We initially had some issues so I checked with one of our network guys and he said it should work. After the customer reconfigured the Nexus to treat the VC-ENET as edge devices (i.e. no spanning tree) it worked, with each VC module joining its LACP group correctly (verified by looking at the LAG ID on the VC connections).


We then created a single SUS so we had 1 LACP pair as active, the other as standby.


This has been working fine until they did some failover testing. As part of this testing they switched off one switch, after which they have lost connectivity to the chassis. Although they initially saw a lot of port flapping at the Nexus, it settled down and they can see some MAC addresses at the virtual switch, blades in the chassis cannot connect out.


Has anyone else any experience of a setup like this, if so are you able to share how the Nexus should be configured? Or is it even valid?


I have asked the customer to reconfigure the uplinks so each VC module only talks to one switch and re-test as well.




Several responses and suggestions:




From Malcolm: 

Must read attached.  I believe Dave Gibson is the author in case you have more questions.


BTW, this document has been posted since Dec under the Virtual Connect Manuals section on  It is very good.


I hope this helps.

NEW! - HP Virtual Connect Flex-10 & FlexFabric Cisco Nexus 5000 & 2000 series Integration 


From Jim: 

We validated a very similar configuration with vPC across 2 Nexus 2000’s switches in January. Failover worked without issue. We used the document referenced by Malcolm as well as this Cisco Configuring Virtual Port Channels material to guide our setup:


Hongjun also chimed in: 

If vPC and Virtual connect is configured right, this will work for sure.


If you have Nexus side config and log and also VC side of config, I can take a look.




Take a look at the guides. Any other comments or suggestions??