How To Change Config Register On Cisco 2960x

What is Configuration Register?

Configuration Annals is a special 16 bits value that tin be configured in Cisco routers. It is mainly used in three cases;

To determine how the router boots
To determine kicking options
To prepare console speed

During the kick, router checks its software and the configuration files. To decide these files, router firstly check Configuration Register. According to its value, router determines what to practise.

Configuration Register Configuration is specially used for Router Password Recovery. Then, what are the values of this special number?

config-register

Configuration Annals 0x2102

The default value of Config Register is 0x2102. With Configuration Annals 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. Especially during Router Password Recovery, this simple configuration is done.

Nosotros tin check this value on Cisco routers with "show version" command. At the output of "testify version" command, Configuration Register value will be at the bottom.

Router# show version

Cisco IOS Software, C800 Software (C800-UNIVERSALK9-M), Version 15.2(4)M4, RELEASE SOFTWARE (fc2)

Technical Back up: http://world wide web.cisco.com/techsupport

Compiled Thu twenty-Jun-13 16:14 by mnguyen

ROM: Arrangement Bootstrap, Version 15.2(2r)T, RELEASE SOFTWARE (fc1)

Router uptime is 35 minutes, 14 seconds

Organization returned to ROM past ability-on

System image file is "flash:c800-universalk9-mz.SPA.152-4.M4.bin"

…

Configuration register is 0x2102

config-register-2102-vs2142

Config Register 0x2142

To featherbed NVRAM configuration, in other words, to featherbed starting time-up configurataion, we tin change Config Register value. Here, the new value that we will set volition be Configuration Annals 0x2142.

How to Change Configuration Register?

In that location are two way to alter Config Register on a router. This tin exist done both in Rommon mode and in configuration mode.

In Rommon mode, information technology can be modify with "confreg" control. Below, we are changing Configuration Register as 0x2142.

rommon > confreg 0x2142

After this configurationi nosotros should reset the router to employ this new value,or to strength the router boot through this config register.

The other way is configuring on configuration fashion with "config- register" command.

Router# configure final

Router(config)# config-annals 0x2142

Later on configuration, you can check the ne value and exist sure nearly the value.

Router# show version

Cisco IOS Software, C800 Software (C800-UNIVERSALK9-M), Version 15.2(four)M4, RELEASE SOFTWARE (fc2)

Technical Support: http://www.cisco.com/techsupport

Compiled Thu twenty-Jun-xiii xvi:14 by mnguyen

ROM: Organization Bootstrap, Version fifteen.2(2r)T, RELEASE SOFTWARE (fc1)

Router uptime is 35 minutes, 14 seconds

Organisation returned to ROM by power-on

System paradigm file is "wink:c800-universalk9-mz.SPA.152-4.M4.bin"

Configuration register is 0x2102 (will exist 0x2142 at next reload)

Over again, nosotros should reload the router for the new config register to accept upshot.

Router# reload

System configuration has been modified. Save? [yes/no]: n

Proceed with reload? [ostend]

Yous can find the detailed information nearly Config Register on Cisco Page.