We have some new 2960's inbound and I had a 2950 laying around. Was wondering if I loaded the 2960S IOS onto it (to get the config setup ahead of time) if there would be any permanent negative impact outside of the device not booting properly? Is there an easy way to recover from this situation if that happens? Can I create config on say 12.4 on the 2950 and just copy/paste into the new switch (2960 running likely 15.X) or will that cause problems? Thanks in advance!
Aside from the switch checking to make sure the firmware is for that model and any number of boot issues you would have if you could force it to install, the 2960S firmware wouldn't fit on the flash of a 2950. The new switch firmware is too large.
I believe the 2950 has an 8MB flash card while the 2960S firmware is ~13MB.
if there would be any permanent negative impact outside of the device not booting properly? Is there an easy way to recover from this situation if that happens?
It won't load, so there is no other impact and there is nothing to recover from.
Can I create config on say 12.4 on the 2950 and just copy/paste into the new switch (2960 running likely 15.X) or will that cause problems?
The 2950 capped at 12.1 from what I saw on Cisco's support site. I don't know what changed from 12.1 -> 15.0.2-SE6. You'd have to look into that.
You could probably get away with some basic stuff but considering the port counts are possibly different and the port types are almost certainly different (Ethernet/FastEthernet on the 2950? to GigabitEthernet on the 2960S) you wouldn't be able to do a direct copy and past. You could copy and paste it into notepad or your text editor of choice and do a replace on FastEthernet for GigabitEthernet and add or remove ports that either did or did not exist on the 2950.
Personally I'd wait and do the config from scratch on the 2960S. It shouldn't take long to do and that way you're not missing a step in converting an old config to a new config and messing with different ports and such.
If you were to load a bad IOS image on a router, switch or AP, you can boot into rommon/recovery mode on the device and use TFTP to download a working image to the unit. I have yet to see a Cisco device without this ability.