stackwise or not?

[enrico.frediani]

Hello everybody.
I am starting to install a couple of C9300 in a campus of my company. The two switches will be installed in two separate datacenters. Every C9500 switch will be connected to every other building of the campus. In this way, every building is connected to both C9300 (in port-channel mode or STP) to guarantee high availability in case that one of the two datacenter goes down.

Now I have a trouble: I can configure the two C9300 in a single stackwise so I have a single virtual switch.
But if I need to update the firmware of the two C9300 (that do not support ISSU) I will cause a disconnection of the buildings of the campus for the time that the C9300 are upgrading, right? In this case is better to install the two C9300 in standalone mode (ad use STP)?

[balaji.bandi]

Sure Stack upgrade required all the switches to reboot.

If you looking high availability, then you need to build 2 Stacks to connect to buildings, that add up the cost.

If you do not like to add up the cost, then you use Layer 3 P2P with OSPF so failover will help you for redundancy, If you looking Layer 2 only then you can think about loop avoidance making a right decisions. ( Traditional looped design with VLANs spanning access switches - below document)

Again this suggestion based on your information my views - so suggest to make small diagram for reference or refer the CVD :

https://www.cisco.com/c/en/us/td/docs/solutions/CVD/Campus/cisco-campus-lan-wlan-design-guide.html