Configuration Register Values and their Meaning

configreg

If you know the value of your configuration register, you can determine its meaning. For information on the meaning of your configuration register setting, including potential issues and fixes, collect the output of the show version command, or the show tech-support command, and input into the Output Interpreter (registered customers only) tool. In order to use Output Interpreter (registered customers only) , you must be a registered customer, be logged in, and have JavaScript enabled.
This table contains some common settings which are valid on most platforms.
Note: Check the appropriate hardware installation guide to verify that the configuration register can be used before you change the configuration register on your router to one of the values in this table.

Configuration Register Setting	Router Behavior
0x102	Ignores break 9600 console baud
0x1202	1200 baud rate
0x2101	Boots into bootstrap Ignores break Boots into ROM if initial boot fails 9600 console baud rate
0x2102	Ignores break Boots into ROM if initial boot fails 9600 console baud rate default value for most platforms
0x2120	Boots into ROMmon 19200 console speed
0x2122	Ignores break Boots into ROM if initial boot fails 19200 console baud rate
0x2124	NetBoot Ignores break Boots into ROM if initial boot fails 19200 console speed
0x2142	Ignores break Boots into ROM if initial boot fails 9600 console baud rate Ignores the contents of Non-Volatile RAM (NVRAM) (ignores configuration)
0x2902	Ignores break Boots into ROM if initial boot fails 4800 console baud rate
0x2922	Ignores break Boots into ROM if initial boot fails 38400 console baud rate
0x3122	Ignores break Boots into ROM if initial boot fails 57600 console baud rate
0x3902	Ignores break Boots into ROM if initial boot fails 2400 console baud rate
0x3922	Ignores break Boots into ROM if initial boot fails 115200 console baud rate