The boot_super.iso is not a CD-ROM or a user-managed file. It is an internal SquashFS or ISO 9660 image embedded within the packages.conf or the system image file. It serves as a —a minimal, read-only filesystem.
During an undisturbed reboot of a Catalyst 9300, this message scrolls by in milliseconds. Most admins never see it unless they have console logging set to debugging or are actively watching a term mon session. The boot_super
To understand the log message, we must first understand the architecture. Traditional Cisco IOS was a monolithic image—a single large file containing all features. IOS XE, however, adopts a modular architecture. It runs a Linux kernel at its core, upon which the IOS process runs as a daemon (IOSd) within a container. During an undisturbed reboot of a Catalyst 9300,
To fully understand the log message, here is a simplified boot sequence of an IOS XE router that uses a boot ISO: Traditional Cisco IOS was a monolithic image—a single