I Have a router 1720. The ios ver is 12.0(4)T. I want to upgrade to the newest ver 12.4(25a). What should I consider before I upgrade. I have no this kind of experience before. Should I consider memory is enough for the new ver? Can I directly upgrade to the new ver? Anyone can provide this kind information or any link I can check it? This router is not on production.
Another question: Do I need to upgrade bootstrap? Or is it included in IOS?