9300 Stack Switching Bengaluru - Amsterdam Code Change Question

[Armymanryno]

Good morning,

I am looking to stack two switches. One is already installed and running (it has been for quite some time). The second switch I ordered arrived today and it is running 17.5.1 Bengaluru. 

My question is - will there be any issues if I downgrade from Bengaluru to Amsterdam 16.12.4 - since it is already racked and running. Or Upgrading/Downgrading from Amsterdam 16.12.4 to Bengaluru 17.5.1?

New Switch - Bengaluru 17.5.1 - C9300-48P ISOXE network essentials

Current Switch - Amsterdam 16.12.4 - C9300-48P ISOXE network essentials

My goal is to have them on the same code, preferably on Amsterdam 17.3.5 since it is the Star Version. But I can accomplish that part remotely once they are on the same platform code level and stacked together.

Any help is appreciated!

Thank you

[Flavio Miranda · Accepted solution]

the correct procedure is you to upgrade the old switch to the same version of the new one and then stack. Make sure the prioty of the old switch is greater then the new switch so that it can be the main switch on the stack. Make sure VTP is in transparent mode and they are running the same STP mode.

[Leo Laohoo]

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@Armymanryno wrote:

Or Upgrading/Downgrading from Amsterdam 16.12.4 to Bengaluru 17.5.1?

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Is the existing 9300, on 16.12.4, have a long uptime?  (Like, >3 months?)

The reason why I am asking is this:  FN - 72323 - Cisco IOS XE Software: QuoVadis Root CA 2 Decommission Might Affect Smart Licensing, Smart Call Home, and Other Functionality

When this bug "hits", it will cause Cisco Smart License to fail to contact the "mother ship".  This will cause a memory leak by a process called "keyman".  (Normal "keyman" process uses about <11k.)  

Next, 16.12.4 is really not a stable OS.  

Finally, if the switches are going to be stacked, please monitor the control-plane daily.