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Factory reset Cisco IOS devices ​

Resetting devices correctly is easier to get wrong than most might think, I'm of course referring to the common mistake of resetting the configuration while forgetting to delete the vlan.dat database and then connecting your fresh switch to a production network with VTP active and the previous VLANs remaining on the switch...this does not make for a fun time.

Here's how to perform a full factory reset the correct way:

Initialize the reset

  1. Connect up your console cable and power on the switch, whilst holding down the mode button:
    • The mode button is commonly positioned on the left interface where you'll find the status lights

This interrupts the boot process before the Flash file system can initialize, and after a short while (continue holding the “mode” button) you will see the following prompt:

txt
Using driver version 1 for media type 1
Base ethernet MAC Address: 4c:30:2d:81:ef:80
Xmodem file system is available.
The password-recovery mechanism is enabled.
The system has been interrupted prior to initializing the
flash filesystem. The following commands will initialize
the flash filesystem, and finish loading the operating
system software:
flash_init
 boot
switch:
  1. Initialize the flash file system with the command: flash_init
txt
switch: flash_init
Initializing Flash...
mifs[2]: 10 files, 1 directories
mifs[2]: Total bytes : 1806336
mifs[2]: Bytes used : 612352
mifs[2]: Bytes available : 1193984
mifs[2]: mifs fsck took 1 seconds.
mifs[3]: 0 files, 1 directories
mifs[3]: Total bytes : 3870720
mifs[3]: Bytes used : 1024
mifs[3]: Bytes available : 3869696
mifs[3]: mifs fsck took 0 seconds.
mifs[4]: 5 files, 1 directories
mifs[4]: Total bytes : 258048
mifs[4]: Bytes used : 9216
mifs[4]: Bytes available : 248832
mifs[4]: mifs fsck took 0 seconds.
mifs[5]: 5 files, 1 directories
mifs[5]: Total bytes : 258048
mifs[5]: Bytes used : 9216
mifs[5]: Bytes available : 248832
mifs[5]: mifs fsck took 1 seconds.
 -- MORE --
mifs[6]: 566 files, 19 directories
mifs[6]: Total bytes : 57931776
mifs[6]: Bytes used : 28429312
mifs[6]: Bytes available : 29502464
mifs[6]: mifs fsck took 21 seconds.
...done Initializing Flash.
  1. Delete the config.text file from the flash directory:
    • This is where the startup-configuration is kept
txt
switch: del flash:config.text
Are you sure you want to delete "flash:config.text" (y/n)?y
File "flash:config.text" deleted
  1. Delete the vlan.dat file from the flash directory:
    • This is where the VLAN database is located
txt
switch: del flash:vlan.dat
Are you sure you want to delete "vlan.dat" (y/n)?y
File "flash:vlan.dat" deleted
  1. Reboot the switch and you’re done:
txt
switch: boot
Loading "flash:c2960s-universalk9-mz.122-58.SE2.bin"...
--- System Configuration Dialog ---
Enable secret warning
----------------------------------
In order to access the device manager, an enable secret is required
If you enter the initial configuration dialog, you will be prompted for the enable secret
If you choose not to enter the intial configuration dialog, or if you exit setup without setting the enable secret,
please set an enable secret using the following CLI in configuration mode-
enable secret 0 <cleartext password>
----------------------------------
Would you like to enter the initial configuration dialog? [yes/no]:
% Please answer 'yes' or 'no'.