XIQ - automatically by pre-selecting the preferred switch OS
Bootloader menu - option to change the switch OS on initial activation only
Startup menu in Switch Engine CLI - post-Bootloader menu prompt
Refer to Read Me First - Switch OS Selection for Universal Hardware shipped with your switch, or visit https://www.extremenetworks.com/support/switch-os-selection/ for information on changing your switch OS after initial activation.
Otherwise, use the instructions in the following topics to configure the software on the switch and prepare it for use.