Cisco 831 and 837 Instructions to erase configuration
STEP 1 – connect a console cable to the router’s console port
STEP 2 – use a terminal program (ie, HyperTerminal) to console to the router
STEP 3 – make sure your settings are 9600bps, 8N1
STEP 4 – power on your router
When you power on the router you should see:
System Bootstrap, Version 12.2(11r)YV3, RELEASE SOFTWARE (fc2)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 2004 by cisco Systems, Inc.
C800/SOHO series (Board ID: 29-129) platform with 65536 Kbytes of main memory
STEP 5 – after you see the above, issue a BREAK (CTRL-Break)
You will get the following prompt:
rommon 1 >
STEP 6 – Type confreg 0x2142 as shown below and hit enter
rommon 1 > confreg 0x2142
** If you hit control-break, but then can not type anything, try changing your flow-control
settings and/or using a different terminal program to console to the router.
STEP 7 – Reboot the router by typing i and then hitting enter as shown below
rommon 2 > i
The router will reboot. After the router reboots you will eventually see:
Processor board ID FHK0920118A (2044528345), with hardware revision 0000
CPU rev number 7
3 Ethernet interfaces
4 FastEthernet interfaces
128K bytes of NVRAM.
12288K bytes of processor board System flash (Read/Write)
2048K bytes of processor board Web flash (Read/Write)
--- System Configuration Dialog --Would you like to enter the initial configuration dialog? [yes/no]:
STEP 8 – Type no and hit enter as shown below
Would you like to enter the initial configuration dialog? [yes/no]: no
STEP 9 – You will see the following below, when you do, hit enter
Press RETURN to get started!
(HIT RETURN)
STEP 10 – You will see the Router> prompt. Type enable and hit enter as shown below.
Router>enable
STEP 11 – You will need to enter into configuration mode, and change the configuration
register and erase the configuration stored in NVRAM. Follow the commands as shown
below (type the bold and italicized commands into the router exactly as shown below).
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#config-reg 0x2102
Router(config)#exit
Router#write erase
Erasing the nvram filesystem will remove all configuration files! Continue? [confirm]
(HIT RETURN)
*Mar 1 00:01:59.311: %SYS-5-CONFIG_I: Configured from console by console
[OK]
Erase of nvram: complete
STEP 12 – Reboot your router using the command sequence shown below
Router#reload
System configuration has been modified. Save? [yes/no]: no
Proceed with reload? [confirm]
(HIT RETURN)
*Mar 1 00:02:49.263: %SYS-5-RELOAD: Reload requested by console. Reload Reason:
Reload command.
Now your router’s configuration has been fully erased and it is ready for your
implementation. Enjoy! If you need addition assistance configuring your router (ie,
setup, securing your network, etc) Network Learning Inc offers consulting services!
Below are screen captures we have provided showing an example on a Cisco 831 router.