Objectives
The simulator ticks each one as soon as the network meets it.
Copy isr4400-universalk9.17.12.04.SPA.bin from 10.0.0.100 to bootflash: and verify its MD5.
Point the boot variable at bootflash:packages.conf (no boot system, then boot system bootflash:packages.conf) and save.
Install the image: install add file bootflash: activate commit (the router reloads).
R1 runs 17.12.04 in install mode and the package is committed (show version, show install summary).
Free bootflash: remove the old bundle image with install remove inactive.
Before you start
install activate reloads the router, so it refuses to start unless the saved configuration boots packages.conf. An activation that is not committed is rolled back at the next reload (the auto-abort timer); "activate commit" in one command commits it for you. install remove inactive deletes package files that nothing uses any more.
Concept
IOS XE install mode: add, activate, commit
IOS XE can boot a .bin bundle directly (bundle mode) or expand it into packages listed in bootflash:packages.conf (install mode, the recommended mode). In install mode you add the image, activate it (the router reloads into it) and commit it. An activation that is not committed is rolled back at the next reload, which protects you from an upgrade that breaks access.
Concept
Upgrading classic IOS: copy, verify, boot system, reload
Classic IOS (and IOS XE in bundle mode) boots one image file. An upgrade copies the new image into flash, checks it is intact, tells the router to boot it, saves that setting and reloads. Every step can fail on its own: no room in flash, a corrupt transfer, a typo in the boot variable, or a boot variable that was never saved.
