Cisco IOS switches and stacking

Notes on stacking Cisco IOS switches:

All versions (IOS, hardware stack, & software stacking) must match.

Verify the IOS version by doing a "show version" or a "dir" and make sure the file names are the same.  

Verify the hardware stack version by doing a "show switch detail" 

Verify the software stacking version by doing a "show platform stack manager all"

If the software stacking version doesn't match, you have to boot into ROMMON to fix it.  But unplug your stacking cables to the new switch first.

1.flash_init

2. set SM_MAJOR_VERSION x.xx

3. boot

then run "show platform stack manager all" again to make sure it shows the version number matches the existing stack.  If yes, unplug the power cables for all switches in the stack, plug in your stacking cables, and then plug in power.