Cisco router Startup Process

When the cisco router is powered on normally, perform the following steps:

1. Test the router hardware

When a cisco router is started, a hardware self-check program POST is initiated. This program checks basic hardware functions including CPU, memory, and network interfaces.

2. search for and locate the cisco IOS image

After the hardware program is tested, the cisco router locates the cisco IOS image. The cisco router can usually locate the IOS software from Flash, we can also set the router to locate the IOS image from the TFTP server and ROM. Most cisco routers view the boot queue defined by the boot system command stored in non-volatile memory (NVRAM) after the hardware detection is complete. The network administrator can manually change the value of the Register to change the location where the router is loaded with IOS by default.

3. Positioning and application configuration

After the cisco router successfully locates the IOS image, the configuration file is applied to perform the router function. The router searches for configuration files from the NVRAM, TFTP server, and CONSOLE ports in sequence. After finding the appropriate configuration file at any of the preceding locations, the configuration file will be used to load the vro.