Updating software on Catalyst 3850+

[pdenableetoavit19698]

Hi there,

want to upgrade the software on a couple of stacked Catalyst 3850+, what is the best way to do it?

any version you recommend as the most stable?

Thank you!

[Flavio Miranda]

Hi @pdenableetoavit19698 

   Best way to pick up the software is going to the release notes and see what the offer and the bug they have, etc.

 IOS with the blue star inside the yellow circle is considered suggested by Cisco.

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3850/software/release/16-12/release_notes/ol-16-12-3850.html

[pdenableetoavit19698]

do you have any suggestions / guide step by step almost on how to actually do the upgrade?

any simple way? possible via usb port/usb memory stick? via cli? tftp?

thanks for any tips

[Flavio Miranda]

Usb is the easier way. Download the IOS, put it on the USB stick , plug in the switch and transfer to the flash.

 Then, execute the upgrade.

Here is a guide

https://www.rogerperkin.co.uk/cisco/software-upgrade-guides/upgrade-software-cisco-3850-switch/ 

[Joseph W. Doherty]

@Leo Laohoo might be able to suggest an solid IOS version.

[Leo Laohoo]

Thanks, @Joseph W. Doherty.

[Leo Laohoo]

What is the purpose of this 3850 stack, is it production or is it a "lab"?

For "lab", any version that does not support Cisco Smart License (CSL) is good enough.  Pick the latest 16.3.X or 16.6.X but avoid 16.12.X.  

If 16.12.X cannot be avoided, make sure to monitor the data- and control-plane memory/CPU utilization daily.  That's right.  DAILY. If the memory utilization goes >52%, reboot the entire stack.  Hard-Cold reboot (remove the power cable, remove the power supplies until the power supplies stop screaming) is the best method if memory utilization goes >52%.  Reboot the stack every four to 6 months.  

For production, if uptime is a big requirement, upgrade to the latest 3.6.X.  Any switch stack on 3.6.X can be guaranteed to have a very long uptime.  An uptime of >5 years on 3.6.X is common.  An uptime of >12 months on 16.X.X is particularly rare.