Replace core Nexus 4k switches with ACI

[Mujtaba Imran Mohammed]

We have Nexus 4k as our core switch at the data center connecting to the WAN (ASRs) and internet (ISR) routers.

We are getting ACI into our DC (2 spine 10 leafs) and was wondering if it is advisable to replace the core Nexus switches with ACI fabric or just extend the VLANs from the core switch to the ACI fabric for internal infrastructure connectivity. Any feedback is appreciated.

[Claudia de Luna · Accepted solution]

Hi @Mujtaba Imran Mohammed ,

In short, I would keep your core, using for port aggregation, a layer 3 boundary and routing manipulation, and anything else that you need that does not belong on the ACI Fabric.   I would move all the Server vlans/SVIs into the fabric.   This gives you a clean L3 out boundary and saves your ACI ports for your servers.   I've done quite a few deployments that started out with ACI Fabric to WAN (despite my caution against such a design) and 90% of them either purchased a collapsed core as part of the project or as part of a subsequent project. 

If you think about what your core does today, port break out for firewalls and other connections, links to WAN and internet Routers...I don't know of many (any?) network engineers who would want to carry all of that on their data center infrastructure.  

Data Center Fabric > Core/Collapsed Core > WAN/Internet is a good architecture.    

[Mujtaba Imran Mohammed]

Thanks Claudia. I had a the setup you recommended in my previous company and wanted to go with this but needed clarification. Appreciate the response.

[Mujtaba Imran Mohammed]

Hi Claudia,

Wanted to reach out to you for further guidance. Hope its fine.
What would be your recommendation for a core switch pair? I have a pair of extra ACI N9K-C93180-FX switches and was wondering if I can use these as core switch pair in nx-os mode at our co-lo/data center. The core switch pair would connect to Internet routers, WAN routers/ ASR routers and internally to ACI fabric.

[Claudia de Luna · Accepted solution]

Hi @Mujtaba Imran Mohammed ,

No worries!  I'm happy to help where I can.

I've done a number of deployments where we used N9Ks as cores without any problems.  If they provide sufficient ports for your design they are very well suited for this.  If that is the case, it looks like you have your core with N9K-C93180-FXs :D

[Mujtaba Imran Mohammed]

Awesome! Thanks Claudia, appreciate your insight. :)

Currently I need 26 ports. The N9K-C93180-FX I have are 48 ports so sufficient enough.

[balaji.bandi]

2 Options :

Option 1 :

Do the existing service and servers able to work with new ACI environment - if not you can connect the existing network to ACI as your 3 tier network

Options 2 :

If the device able to Support and ready to Move to ACI Environment - Build new ACI and cut over to new environment 1 by 1 and test 

Note: I do recommend like big bang approach here.