How To Verify The Configuration Register Entry On A Cisco 2500 Series Router
Configuration Register
What is Configuration Register?
Configuration Register is a special 16 bits value that can be configured in Cisco routers. It is mainly used in three cases;
- To determine how the router boots
- To determine boot options
- To set console speed
During the kicking, router checks its software and the configuration files. To make up one's mind these files, router firstly check Configuration Register. According to its value, router determines what to do.
Configuration Register Configuration is peculiarly used for Router Password Recovery. And then, what are the values of this special number?
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 featherbed this configuration, we tin change the default value. Peculiarly during Router Countersign Recovery, this simple configuration is done.
We can check this value on Cisco routers with "evidence version" control. At the output of "bear witness version" command, Configuration Register value will be at the bottom.
Router# evidence version
Cisco IOS Software, C800 Software (C800-UNIVERSALK9-1000), Version 15.ii(4)M4, RELEASE SOFTWARE (fc2)
Technical Back up: http://www.cisco.com/techsupport
Copyright (c) 1986-2013 by Cisco Systems, Inc.
Compiled Thu 20-Jun-13 16:xiv by mnguyen
ROM: Arrangement Bootstrap, Version xv.2(2r)T, RELEASE SOFTWARE (fc1)
Router uptime is 35 minutes, 14 seconds
Arrangement returned to ROM by power-on
Arrangement image file is "flash:c800-universalk9-mz.SPA.152-4.M4.bin"
…
Configuration annals is 0x2102
Config Annals 0x2142
To bypass NVRAM configuration, in other words, to bypass start-up configurataion, we tin change Config Register value. Here, the new value that we will set will be Configuration Register 0x2142.
How to Change Configuration Annals?
There are two way to modify Config Register on a router. This can be done both in Rommon mode and in configuration style.
In Rommon mode, it can be change with "confreg" command. Below, nosotros are changing Configuration Annals as 0x2142.
rommon > confreg 0x2142
Subsequently this configurationi nosotros should reset the router to use this new value,or to forcefulness the router boot through this config register.
The other style is configuring on configuration mode with "config- register" command.
Router# configure concluding
Router(config)# config-register 0x2142
After configuration, you tin can check the ne value and be sure about the value.
Router# bear witness version
Cisco IOS Software, C800 Software (C800-UNIVERSALK9-M), Version 15.two(4)M4, RELEASE SOFTWARE (fc2)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2013 past Cisco Systems, Inc.
Compiled Thu xx-Jun-13 xvi:xiv past mnguyen
ROM: System Bootstrap, Version fifteen.two(2r)T, RELEASE SOFTWARE (fc1)
Router uptime is 35 minutes, xiv seconds
System returned to ROM by power-on
Organisation image file is "flash:c800-universalk9-mz.SPA.152-4.M4.bin"
Configuration register is 0x2102 (will be 0x2142 at next reload)
Once again, we should reload the router for the new config register to take upshot.
Router# reload
System configuration has been modified. Salve? [aye/no]: n
Proceed with reload? [confirm]
You lot tin find the detailed information about Config Register on Cisco Page.
How To Verify The Configuration Register Entry On A Cisco 2500 Series Router,
Source: https://ipcisco.com/lesson/configuration-register/
Posted by: kelleyinack1988.blogspot.com
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