Start-up flowchart for Cisco routers

This diagram is a comprehensive description of the router's startup process, which has several areas to explain.

Ladies and gentlemen, please note:

1. Boot field startup fields

2, run ROM monitor rom monitoring mode

3, use the iOS in ROM (rxboot mode) running in ROM the mini iOS

4, Config reg bit{13,6} for the corresponding configuration registers corresponding to the bit

First, the router after the power, run the ROM of the Post program (the Power of Self test) on the hardware of the router to detect, commonly known as the addition of self test.

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Second, after the test passed immediately after the implementation of the ROM Boot program (bootstrap), and based on register value (register) to determine the starting mode.

The format of the register value is: 0x21yz

Status of column: 0x210z load configuration file from NVRAM

0X214Z does not load configuration files from NVRAM

Status of z column: 0x21y0 from Rommon boot prompt to:> (press Ctrl+break when router starts)

0x21y1 from mini iOS boot prompt: Router (boot) >

0x21y2 from the Flash start prompt for:router>

We often use the two register values: 0x2102 (Normal), 0x2142 (not read the saved configuration).

If you start normally, look for iOS mirrors in Flash by boot program. If an iOS mirror is found, the

Starts normally after reading. If the iOS image is not found, enter boot mode, which is the mini iOS boot. In boot mode, you can use the iOS on TFTP or use Tftp/x-modem to recharge the router with iOS. If mini iOS also fails to boot, enter ROM monitor mode.

Iv. after reading iOS and initializing successfully, the bootstrapper will decide to load or not load the boot configuration file with a higher register value. If you choose to load, locate the boot configuration file in NVRAM and load into RAM to become the run profile. If you choose not to load or do not start the profile at all, the router enters the query configuration mode and makes the basic configuration of the router in question and answer.

Enter the user mode, the START process is complete.