How configure config register in ROMmon?
- Boot into the ROMmon mode.
- Change the configuration register such that the startup config is not loaded.
- Boot into IOS.
- Go to the privileged exec mode and copy startup config to running config.
- Change the passwords.
- Save the running config to startup config.
Full Answer
How to change configuration register in ROMMON mode?
This can be done both in Rommon mode and in configuration mode. In Rommon mode, it can be change with “ confreg ” command. Below, we are changing Configuration Register as 0x2142.
How to change the virtual configuration register from the ROM monitor?
To change the virtual configuration register from the ROM monitor manually, enter the confreg command followed by the new value of the register in hexadecimal format, as shown in the following example: The value is always interpreted as hexadecimal.
How do I use the ROM monitor on my Cisco router?
If there is no Cisco IOS software image loaded on the router, the ROM monitor runs the router. To use the ROM monitor, you must be using a terminal or PC that is connected to the router over the console port. Perform these steps to configure the router to boot up in ROM monitor mode the next time it is rebooted.
Why does the switch go into ROMMON mode when booting?
12-13-2012 11:45 AM 12-13-2012 11:45 AM The configuration register has been changed incorrectly. The configuration register value of 0x0 always brings the switch to ROMmon mode. The typical configuration register is 0x2102, with the boot system flash command pointing to the system image to load
How do I set the config register value in ROMmon mode?
In Rommon mode, it can be change with “confreg” command. Below, we are changing Configuration Register as 0x2142. After this configurationi we should reset the router to use this new value,or to force the router boot through this config register.
How do I change my Cisco config register?
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 0x2102?
The factory default setting for the configuration register is 0x2102. This indicates that the router should attempt to load a Cisco IOS Software image from Flash memory and load the startup configuration with a console speed of 9600 baud.
What is 0x2142 config register?
Explanation: The default configuration setting is 0x2102, which tells the router to load the IOS from flash and the configuration from NVRAM. 0x2142 tells the router to bypass the configuration in NVRAM so that you can perform password recovery.
What is config register 0xf?
Config-Register is basically a hexadecimal or decimal value that represents. the 16-bit configuration register value that will be used the next time the switch is. restarted. The value range is from 0x0 to 0xFFFF (0 to 65535 in decimal).
How do I change the registration value?
To change the value of a registerIn the Registers window, use the TAB key or the mouse to move the insertion point to the value you want to change. When you start to type, the cursor must be located in front of the value you want to overwrite.Type the new value. Caution.
What is configuration register function?
The Configuration Register. When a router starts up it needs to know which software to load and which configuration file to use. The way it determines these two things is by looking at its configuration register setting and its startup configuration in nonvolatile RAM (NVRAM).
Which command displays the configuration register setting?
The show version command provides you with the current configuration register setting.
How do I change the boot sequence in Rommon mode?
You cannot change the boot parameters but you can definitely upload a new image from tftp in rommon mode.
What does copy running config startup config do?
On the Class A Flash file system platforms, the copy system:running-config nvram:startup-config command copies the currently running configuration to the location specified by the CONFIG_FILE environment variable. This variable specifies the device and configuration file used for initialization.
The Purpose of The Configuration Register
The configuration register can be used to change router behavior in several ways, such as: 1. how the router boots (into ROMmon, NetBoot) 2. option...
Configuration Register Values and Their Meaning
If you know the value of your configuration register, you can determine its meaning. For information on the meaning of your configuration register...
Troubleshoot Configuration Register Issues
An inappropriately set configuration register can cause many problems, such as: 1. The configuration file is ignored. 2. There is no output or garb...
Set The Configuration Register
Use the table in Configuration Register Settings and their Meaning to determine the desired configuration register setting (usually 0x2102).
Configuration Register 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. So, if we need to bypass this configuration, we can change the default value.
Config Register 0x2142
To bypass NVRAM configuration, in other words, to bypass start-up configurataion, we can change Config Register value. Here, the new value that we will set will be Configuration Register 0x2142.
How to Change Configuration Register?
There are two way to change Config Register on a router. This can be done both in Rommon mode and in configuration mode.
What is a virtual configuration register?
The virtual configuration register is in nonvolatile RAM (NVRAM) and has the same functionality as other Cisco routers. You can view or modify the virtual configuration register from either the ROM monitor or the operating system software. Within the ROM monitor, you can change the configuration register by entering the register value in hexadecimal format, or by allowing the ROM monitor to prompt you for the setting of each bit.
Why use ROM monitor?
You can use the ROM monitor to perform certain configuration tasks, such as recovering a lost password or downloading software over the console port. If there is no Cisco IOS software image loaded on the router, the ROM monitor runs the router.
Why is error message only displayed on console?
Because the ROM monitor console download uses the console to perform the data transfer, when an error occurs during a data transfer, error messages are only displayed on the console once the data transfer is terminated.
Does Cisco router boot into OS?
The router remains in ROM monitor and does not boot the Cisco IOS software. As long as the configuration value is 0x0, you must manually boot the operating system from the console. See the boot command in the " Command Descriptions " section in this appendix. After the router reboots, it is in ROM monitor mode.
