9300 Switch Stack Design Question - 2 Stacks of 4 or 1 Stack of 8?

[klopez138]

We're about to replace all of our access switches with new 9300s and I currently have 2 stacks of 4 in one office. I have the capacity to condense bot]h stacks into one and I'm curious as to what the design considerations are of the two topologies depicted in the drawing. I should mention that SVIs for all VLANs are on the core switches and there is no local DHCP on the access switches either. I'm leaning towards Option B and keeping them separate so that in the event there are layer 2 issues, it will only affect half of the endpoints in this office. If anyone out there would like to share their input or experience with a similar setup I'd love to hear some opinions on the matter. Thanks for looking.

[Reza Sharifi]

I also think option B is a much better option. This way, if there is a problem with the stack, you don't loose everything. If you have the capacity on the core switch and up-time is essential to your business, you can also go with 4x2=8 as another option to give you more resiliency.

HTH

[Joseph W. Doherty · Accepted solution]

For resiliency, I fully agree with Reza that option B is a better choice. Of course, using the same logic, we could argue four stacks of 4, 2 units each, or perhaps having all 8 downstream switches as individual switches would be best of all.

Some of the counter arguments to have a single stack are: each "split" requires more links between the upstream and downstream devices, you have more "devices" to manage and if there is much East-West traffic, it may be more likely to congest going North-South rather than East-West within the same stack.

Personally, I think either is fine, both have their minor advantages and disadvantages.

In my last job often we were limited in fiber runs (between "hub" and "spoke") and/or we didn't want to increase the number of (logical) devices we needed to manage. For example, in my last job we had over 5,000 Enterprise networks device (my personal allotment was about 500).

Again, though, either should be fine, whatever seems to work best for you and your environment.

[bartchamness]

This option saves you lots of money.

[Leo Laohoo]

FYI: Catalyst 9300, if loaded with 16.10.X (and later), can support up to SIXTEEN (16) switches in a stack.