What is Confreg 0x2102?

The default value of Config Register is 0x2102. With Configuration Register 0x2102 value, the router boots from NVRAM and the normal router precedures works. The configuration stored in NVRAM is the startup configuration. Especially during Router Password Recovery, this simple configuration is done.

How do I change my configuration register to 0x2102?

To change the configuration register so that the router does not ignore or skip the startup configuration upon reboot or power cycle, complete these steps: From the Router# prompt: Type configure terminal, and press ENTER. Type config-register 0x2102, and press ENTER.

What is config register in Cisco router?

Cisco IOS routers and switches use a configuration register for some specific settings. These are settings that are not stored in the startup or running configuration. There are 16 bits (4 hexadecimal digits) reserved for the configuration register.

How do I get my router out of ROMmon mode?

If your router gets stuck in ROMmon mode during the boot process, examine the value of the configuration register by entering the confreg command. Change the value of the configuration register as shown below to stop the router to go into the ROMmon mode after reloading.

Which command will change the configuration register to 0x2100?

Use command “config-regiter 0x2100” to change configuration register setting.

What is config register 0x142?

Symptom: When start-up configuration is ignored by setting ROMMON boot parameter (SWITCH_IGNORE_STARTUP_CFG) or start-up configuration is removed, the default config register value will be shown as 0x142 instead of 0x102. OR “write erase” is executed and switch is booted.

What is config register 0x0?

If you set the configuration register boot field to 0x0, you must boot the operating system manually with the boot command. If you set the configuration register boot field to 0x1, the router boots using the default ROM software.

What does Rommon mode mean?

For those of you that are not familiar with the term ROMmon (ROM monitor) mode, it is a bootstrap program that initializes the hardware and boots the Cisco IOS software when you power on or reload a router or switch. This value can be changed from the console of the router.

What does the configuration register 0x0002 mean?

0x0002-0x000F- Specifies a default netboot filename. Enables boot system commands that override the default netboot filename. Causes the system to use the secondary bootstrap. This is typically not used (set to 0). An inappropriately set configuration register can cause many problems, such as:

Why is configuration register not displayed in Cisco IOS-XE?

This is because Cisco IOS-XE doesn’t use this config-register command and provides alternate CLI commands to handle the same. Note: The incorrect display of configuration register value on show version output is removed from 16.12.4 and 17.3.1 release onwards.

What’s the difference between 0x102 and 0x 2102?

The difference is very small. 2102 includes fallback to booting from ROM if netboot fails. 0x102 does not fallback to ROM. Please see screenshots. Here are some commonly asked questions and answers to help with your adoption of Cisco DNA Center Wireless.

What happens if Cisco IOS-XE fails to boot?

Note: If a system running on Cisco IOS-XE fails to boot for 5 consecutive times in less than 25mins of uptime for each reload, then the software auto-sets ROMmon variable MANUAL_BOOT=”yes”. In other words, if a system fails to boot for any reason it auto boots into ROMmon after 5 consecutive tries.