3650 Stackwise "Sweet Spot"

[michael brock]

I currently have (5)3650's stacked together, but need to add more ports. I know we can stack up to (9) switches together, but my network architect is saying that while you can, 5 switches is the sweet spot and he is recommending we start another stack.

Any validity to this?

[balaji.bandi]

You can go maximum as you mentioned, Look at the risk point of view very high, instead you can split in two 2 stacks, so you have more redundancy and easy maintenance for stack upgrade or so on. ( make sure you need a big stack to cable it's not a standard cable not going to reach end to end.)

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3650/hardware/installation/guide/Cat3650hig_book/HIGINSTL.html#71220

[Joseph W. Doherty]

Have no direct experience with 3650s/3850s, but on the prior gen, i.e. the 3750s, have dealt with nine units stacks.  Don't recall ever having an operational issue with them, although, at least on the 3750s, command line process can become very slow with large numbers of units in the stack.

About the only major advantage of a single large stack, you don't need additional uplinks for another stack.  Of course, all the minor advantages also still apply, i.e. having one logical device rather than two.  That said, assuming uplinks isn't a problem, and the other advantages are not important to you, nothing wrong with having a separate stack.

BTW, what Balaji mentions about not having a single stack cable long enough for a large stack, I think he has in mind the 1 meter cable.  The 3 meter cable should be long enough.  Or, you can alternate how you connect the stack cables, and then you don't need a long cable.  See middle example in image in: http://networkswoot.blogspot.com/2014/02/3850-switch-stacks-stackcabling-and.html

[Kanan Huseynli]

Hi,

In one project we have done 8 or 9 switches in single stack 6years ago. I dont remember that there was problem.

Regarding cabling there is method to do it with shorter cables:

Take one paper an write numbers (number of switches) with method of: 1 on the top, next number on the left, next to next number on the right (in general it should like circle) and etc. Like below for 7 switches:

          1

    2            3

4                     5

     6           7

Then , if you connect switches orderly, you will have FULL Stack, like below:

         1

     /       \   
 2            3

/                \

4                5

/                   \

6   -------   7

HTH,