Setup Mode Upgrading and boot process of the IOS

The setup mode on Cisco routers is a configuration mode that allows basic configuration of the router. When a Cisco router is powered on, it goes through a boot process that includes a series of tests to verify that the hardware is functioning properly. Once the hardware is verified, the router loads the IOS (Internetwork Operating System), which is the software that provides the router’s functionality.

The IOS is stored in non-volatile memory, which means that it is retained even when the router is powered off. The IOS can be upgraded to a new version using the Cisco IOS Software Upgrade Tool. The upgrade process involves downloading the new IOS image and then copying it to the router’s flash memory.

The boot process involves the router’s firmware finding the IOS image and loading it into memory. During this process, the router also checks its configuration files and initializes its interfaces. Once the IOS is loaded, the router enters the user EXEC mode, which is the first level of access to the router’s CLI. From there, the administrator can enter the privileged EXEC mode, which provides access to all the router’s commands.

The boot process can be interrupted by pressing the Break key on the console, which will take the router to ROM monitor mode. This mode allows the administrator to perform diagnostic tests and change the boot process. However, it is important to note that changing the boot process can render the router unusable if not done correctly.

In summary, the boot process on Cisco routers involves a series of tests to verify the hardware, loading of the IOS into memory, initialization of the router’s interfaces, and entry into the user EXEC mode. The IOS can be upgraded using the Cisco IOS Software Upgrade Tool, and the boot process can be interrupted to enter the ROM monitor mode.