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Designing a collapsed spine/leaf design with 4 switches

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  • 1.  Designing a collapsed spine/leaf design with 4 switches

    Posted Feb 22, 2024 09:21 AM


      Seeking advice from the group as I am quite new to Aruba (but with extensive Data Center design with Cisco/Juniper/Arista). 

      The customer is refreshing the DCs, currently, they are using a collapsed core for both campus and DC. 

      The campus side is undergoing a refresh with several CX stacks for WiFi and Wired connectivity. Now I am working on displacing the 4 x core Cisco Nexus 5K. 

      There are 2 comms rooms with only several hundred metres apart so I won't consider them as cross-site.  Then I am thinking of proposing a collapsed spine/leaf EVPN-VXLAN design with 2 switches in each comms room.  Given the small scale, 2 x 48 ports as a collapsed spine/leaf would be good enough for each comms room.

      The question is, can I cross-connect the 4 switches and make them as spine/leaf as well as border leaf (connect external networks)?  

      If it does, can I leverage Aruba Central to manage this network?  And what role should I config the switch to? 


      Thanks in advance. 

  • 2.  RE: Designing a collapsed spine/leaf design with 4 switches

    Posted Feb 23, 2024 01:27 AM



    Thanks for reaching out. This question is indeed very interesting. When it comes to network design, most often, there is no right or wrong. However, there may be better or worse ways how to design your network depending on the point of view, the budget, and the design goals.


    In general, whenever possible, if you are looking for the best possible solution, you may want to follow the "Validated Solution Guide (VSG)": https://www.arubanetworks.com/techdocs/VSG/docs/040-dc-design/esp-dc-design-020-network-design/


    I have not seen any validated design with Aruba which does anything like Juniper's collapsed spine architecture. My question would be why you want to have a VXLAN fabric with only 4 nodes. Isn't that an overkill? Would a normal L2 data center design not fit your needs, too?


    Anyway, with 4 nodes building a VXLAN fabric, you have the option to run them in the role of border leaf switches and instead of connecting the border leafs to a spine layer (regular leaf-spine architecture) you may fully mesh the leafs. That brings you the same functionality and performance but wouldn't scale very well when adding more leaf pairs. You may still use all the VXLAN features Aruba has.


    Regarding Aruba Central: Are you looking into the direction of NetConductor or would you simply want to onboard the switches as UI groups?


    I hope this helps. Maybe there is other opinions here.





  • 3.  RE: Designing a collapsed spine/leaf design with 4 switches

    Posted Feb 23, 2024 03:00 AM
      |   view attached

    Hi, I would mirror the question about if this requires EVPN for only four switches. It might be that you are considering the four core switches as the spine and other CX switches out on the campus as the leaves?

    This is what I run. An EVPN network spread over a campus that allows for macro level network segmentation. The spine switches are also borders (to connect to legacy core for example). I found the attached doc extremely helpful in my understanding of how Aruba does this.

    I don't think the concepts are different to any other vendor. You could use your past experience to design what is right for the situation and have confidence the CX are capable of achieving it.

    Regarding central, I haven't had enough confidence in it (or maybe just experience) to use it for complex designs. I would certainly recommend the learning path be on the CLI for the richer ability to run commands that aid understanding. It could be moved to central once you are past that stage. I just found that if you don't have a large scale of boxes to benefit from "configure once, push to many" that doing CLI commands in netedit etc doesn't hold as much value compared to if you had 1000 edge switches with similar config (where the benefit is obvious).


    EVPN_-_DCN_-_10.6_-_IVRL.pptx   12.78 MB 1 version

  • 4.  RE: Designing a collapsed spine/leaf design with 4 switches

    Posted 14 days ago

    This a grear presentation. Is it from some lecture or video? Is it available somewhere? 

    -- tommyd

  • 5.  RE: Designing a collapsed spine/leaf design with 4 switches

    Posted 10 days ago
    Hi, this was created by Aruba a few years ago and there was an associated Youtube but I can't find it.

    This does have a good list of videos relating to CX and EVPN

  • 6.  RE: Designing a collapsed spine/leaf design with 4 switches

    Posted 9 days ago

    Hi IanNightingale
    That's a real good PPT from many aspects. Thanks for that.