3850 IOS software versions

[hmc2500]

What is the differene between the 3.7E.x and 16.x.x software versions? The switches that I'm about to add to a stack are at 03.07.04E (mixed stack.WS-C3850-48T-S and WS-C3850-24XS-S). I wonder if it's best to upgrade and to what version. 

And are there no tar IOS versions available for download?

[Philip D'Ath]

The 16.x train was all about adding programmability and support for DNAC.

I'm still running all of the 3850's I look after on the 3.x train.

[Philip D'Ath]

ps. If you do uprade to 16.x watch your ROMMON versions.

[Leo Laohoo]

1. 3.7.4 is not a reliable and stable firmware version to be "nesting". One of my "favorite" bugs is CSCuo14511. (A lot of people are affected by this bug that the "number" of actual TAC Cases associated to this bug is now "private".)
2. Before adding the new switch member to the stack, downgrade it first to 3.7.4 and see if it boots. If it does, then it is up to you if you want it to join the stack (or not).

[hmc2500]

I think I will stick with 03.07.04E for now since we have a couple of stacks running fine with this version. 

What is the difference between the following and how do you know which one of them you are running on a switch? 

CAT3850/3650 UNIVERSAL
cat3k_caa-universalk9.SPA.03.07.04.E.152-3.E4.bin
25-May-2016
312.96 MB

CAT3850/3650 UNIVERSAL W/O DTLS
cat3k_caa-universalk9ldpe.SPA.03.07.04.E.152-3.E4.bin
25-May-2016
312.95 MB

[hmc2500]

I see the second version has ldpe added to the name. However I'm still not sure what the difference is.