Nexus dual-sided vPC design with dual-connected

Unanswered Question
Feb 20th, 2012


I would like to make a design with 4 Nexus 5596UP. 2 of them equipped with Layer 3 Expansion Module  so they can serve as core layer and the other 2 Nexus used as Layer 2 for aggregation server layer.

  • The 2 Nexus in the core layer will run HSRP and will peer with ISP via BGP for Internet connection
  • The 2 Nexus in the aggregation layer will be configured as layer 2 device and have FEX and switches connected to them

What I am ensure of is how the vpc and port-channel configuration should look like between the 4 nexus. What I was thinking is to run vpc between the 2 Nexus in the aggregation layer and between the 2 Nexus in the core layer. Than I was thinking of connecting each Nexus in the aggragtion layer to both Nexus in the core layer using port-channel and vice-versa.

I have made a drawing og the design I have described above:


Do you have any recommendations/comments or improments to this design?



I have this problem too.
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Oleksandr Nesterov Mon, 02/20/2012 - 07:13

Laurent, you can get inspiration in following example:

Topology is called back-to-back vpc - both peers in one vpc domain will have one virtual port-chanel to downstream switches, and same from downstream switches perspective.

Please remember one important restriction: VPC domain numbers must be unique within each vpc domain (pair o switches).


Alex Tue, 02/21/2012 - 00:23

Hi Alex,

Thanks a lot for replying to my post. It looks like that is what I am looking for. Instead of ussing 2 links to each pair, is it possible to bundle 4 links on each side like on this picture:

Is back-to-back the best practice design in my case?




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