IOS upgrade / installation

[M.Sultan]

Hello

I have two 3750 switches, these two running bit different iOS versions, when i stack these two switches there is a mismatch which causes to not stack.

i want to upgrade one of the iOS to make is equal.

Any link to download reliable iOS for my switch ?

an how to upgrade / install new iOS into my switch ? do i still need to remove first iOS from the switch ?

thank you 

[Joseph W. Doherty]

What particular models of the 3750s?

"Any link to download reliable iOS for my switch ?"

Cisco no longer provides downloads for 3750s as they're now EoL.  However, you may be able to copy the bin from one switch to the other.

Do you need to remove IOS first?  Depends whether there's sufficient flash free space to hold different IOS versions.  That said, often you do need to remove the current IOS installed version to run one IOS version of your choice.

Normally, if you have the tar file, you run an install using that, and it does everything needed.  Without such, you'll likely need to manually delete the installed IOS version, copy the bin file to the 3750 and manually update the bootvar.

The master of the 3750 series is @Leo Laohoo (who also might be able to point you to using a later series 3750 IOS on earlier platforms).

[M02@rt37]

Hello @M.Sultan,

Depending of the exact 3750 model:

https://software.cisco.com/download/home/277987617?catid=268438038

3750 is EoL: https://www.cisco.com/c/en/us/products/switches/catalyst-3750-series-switches/eos-eol-notice-listing.html

Why you don't donwload the IOS from the other switch and then install/upload it?

As concerned the question about deleting the former IOS, it depends of the space memory left on your Switch. But if you can, it's generally recommended to keep a copy of the previous IOS image on the flash memory in case you need to revert to it.

[Leo Laohoo]

What are the exact models of the all the switches in this stack?