The configuration register can be used to change Cisco router behavior in several ways, such as:
|How the router boots (into ROM Monitor (ROMmon) or NetBoot).|
|Options while booting (ignore configuration, disable boot messages).|
|Console speed (baud rate for a terminal emulation session).|
This Cisco How-To Tutorial explains how to interpret the config register setting and how to solve problems resulting from an improper setting.
To view the current setting of the configuration register, establish a console or Telnet session with the router.
If you cannot establish a console session, or if you see only garbage characters, a speed mismatch between the router and the terminal emulation software could be the cause.
Change the baud rate of your terminal emulation software.
These are possible settings:
If the router is in ROMmon mode, issue the confreg command.
You receive an explantion of your current setting similar to this:
rommon 7 > confreg
console baud: 9600
boot: the ROM Monitor
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.
For most purposes, the factory default setting of the configuration register is the most appropriate.
To change the configuration register to this setting, issue the configuration-register 0x2102 command, as shown:
From ROMmon mode, issue the confreg 0x2102 command, as shown:
rommon 1 >confreg 0x2102
For further information on using other settings refer to:
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