Here in the office the Access Layer of our switching infrastructure is handled completely with a 7 unit stack of Cisco 3750X switches. There is no need for these to do any routing other than intervlan so when purchased 3 years ago we just ordered the IP Base licensing level. Well from what I can tell there is a universal code base and a licensed feature level of each code revision. The universal naming convention looks like c3750e-universalk9-mz.122-55.SE1 while the ipbase looks like c3750e-ipbasek9-mz.150-2.SE6. What I found is that I do not have the ability to download the universal code of later releases due to my licensing level and possibly the lack of SmartNet I keep on these, but I do have access to the ipbase code. When attempting to update the code on this stack I was presented with the error
Error: The image in the archive which would be used to upgrade Error: system number 1 does not support the same feature set.
After some searching I found reference to others trying to go from IP Base to Advanced IP Services code having to put the /allow-feature-upgrade switch on the archive download-sw code in order to allow the upgrade as well as it seems a downgrade. Evidently this feature came about with IOS version 12.2(35). Now the upgrade progressed and I have happy little upgrades switches.
switch#archive download-sw /overwrite /allow-feature-upgrade tftp://172.16.3.40/c3750e-ipbasek9-tar.150-2.SE6.tar Loading c3750e-ipbasek9-tar.150-2.SE6.tar from 172.16.3.40 (via Vlan3): !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! [OK - 25671680 bytes] Loading c3750e-ipbasek9-tar.150-2.SE6.tar from 172.16.3.40 (via Vlan3): !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! examining image... extracting info (106 bytes) extracting c3750e-ipbasek9-mz.150-2.SE6/info (522 bytes) extracting info (106 bytes) Stacking Version Number: 1.49 System Type: 0x00000002 Ios Image File Size: 0x0137E200 Total Image File Size: 0x0187BA00 Minimum Dram required: 0x08000000 Image Suffix: ipbasek9-150-2.SE6 Image Directory: c3750e-ipbasek9-mz.150-2.SE6 Image Name: c3750e-ipbasek9-mz.150-2.SE6.bin Image Feature: IP|LAYER_3|SSH|3DES|MIN_DRAM_MEG=128 .... All software images installed.
Another note about this upgrade I found in the official release notes is any upgrade from 15.0(2)SE to later will result in a microcode upgrade which when unmitigated will lead to an exceptionally long restart of the switch. You can mitigate this either by using the /force-ucode-reload parameter when downloading the code to the devices or by using the archive download-sw /upgrade-ucode privileged EXEC mode command afterwards.
