Sometimes, for any number of reasons, you’ll find yourself wanting to downgrade the firmware on your Cisco edge devices to match what you have running in the core. Fortunately, at least for the 9100-series switches, this is basically the same as upgrading the firmware. I’ve included the commands to run here, and also the full output of the process. For the director-class switches, there are a few more things to do, such as clearing out the space on the standby supervisor as well as the active sup card. I’ll try and post something 9500-series specific in the next few weeks.
In short, do this (assuming you’re loading version 3.3(4a) of the code):
copy running-config startup-config
copy startup-config tftp://192.168.101.9/startup-config_FOSLAB5A08_28072010
copy tftp://192.168.101.9/m9100-s2ek9-mz.3.3.4a.bin bootflash:m9100-s2ek9-mz.3.3.4a.bin
copy tftp://192.168.101.9/m9100-s2ek9-kickstart-mz.3.3.4a.bin bootflash:m9100-s2ek9-kickstart-mz.3.3.4a.bin
show version image bootflash:m9100-s2ek9-mz.3.3.4a.bin
show incompatibility system m9100-s2ek9-mz.3.3.4a.bin
install all system bootflash:m9100-s2ek9-mz.3.3.4a.bin kickstart bootflash:m9100-s2ek9-kickstart-mz.3.3.4a.bin
You can also see the full output here. Note that this process works equally well for HP’s 9124e switches (the type you find in the back of c7000 blade chassis for instance), although you should be downloading the firmware from HP’s site, not Cisco’s.