Cisco Catalyst Center DR Design

[Toy Thompson]

We are looking at implementing a 1+1+1 DR solution. We have two Data Centers (DC01 and DC02) with layer 2 separation. We also have a Campus infrastructure attached to both DCs using layer 2.
We have a single node cluster deployed in DC01 and we are going to implement a single node cluster in DC02 with a Witness Site in our Campus infrastructure.

Since we have L2 between the 3 sites can I add Cluster1, the Witness Site and Cluster 2 on the same network/subnet?
If I cannot what and all three have to be on separate networks, what DR VIP do I use does it reside on the Witness Site network or on one of the Cluster networks?

[balaji.bandi]

As per cisco the Witness node to be not part of the any DC, should be 3 rd DC network.

But some time this is not possible like going to AWS or any other cloud and install Witness node

you can have risk installing Witness node one of the DC network - if that DC network isolated then you can not see other DR Node.

But DNAC is just a orchestration tool and assurance system, some business can accept the risk, since you have deal with different DR outage than DNAC DR,

there are some Limitation with DR (mainly Assurance Data - that is odd here and understand risk before you deploying DR)

there is good presentation i suggest :

https://www.ciscolive.com/c/dam/r/ciscolive/emea/docs/2023/pdf/BRKOPS-2161.pdf

[Toy Thompson]

Thank you for the response. The Witness Site/Node is not part of either DC. The question however is since all three sites are connected on L2 can I use the same subnet for Cluster1, Cluster2 and Witness site/Node.

[balaji.bandi]

i think yes - Witness node required only reachability, if they are layer 2 and they are in the RTT why not build 3 node cluster ? (so you can avoide some of the sitautions.)

[Preston Chilcote]

@balaji.bandi We don't support a 3 node cluster that spans DCs.  It's not the intended design.  Please stick with Disaster Recovery deployment for these scenarios.

@Toy Thompson Yes, I don't see why you can't use the same subnets on all the components.  The ciscolive presentation that Balaji provided is a good one for DR in general, so I hope you looked through it.

[balaji.bandi]

I know 3 Node cluster should in same DC, But technically if that meets latency requirement - i do not see any reason here and being other DC ( may be quorum and RTT issue iguess here). Virtually i have tested in test bed it works as expected with in latency (not producton level) - any wayu that is cisco standard of deployment.

[Toy Thompson]

Thanks for the response...the question is not around spanning multiple nodes in the same cluster between DCs, it is around the DR solution....We have two separate single node clusters in the DCs do they have to be on separate networks or subnets when we implement DR or can the two separate clusters and the witness site be in the same network.