How to restore a Cisco IOS Switch back to factory defaults

River view at Tamsui, Taiwan.

Yes, you know what I am talking about! Restoring a switch back to factory defaults is a daily operation of a Cisco Partner's job!

Commands "write erase" or "erase startup-config" followed by a power-off is good enough for IOS routers to go back to factory default state. But this is not true for IOS switches.


Switches store VLAN and VTP information in "flash:vlan.dat", not in any part of configurations! VLAN information cannot be cleared by either "write erase" or "erase startup-config" because it is not there!

Therefore, to restore a IOS switch to factory default, we have to do one additional step to clear those leftover states: delete that "flash:vlan.dat" before power-off!

Also note this, IOS switches will try to observe and learn the VTP domain name if its "flash:vlan.dat" is gone while booting. If you "reload" the switch instead of turning off power, its VLAN information might again not be clean.

Just power-off the switch!


Let me summarize how to restore a Cisco IOS Switch back to factory defaults:

1. Step 1: "write erase" or "erase startup-config"
2. Step 2: "delete flash:vlan.dat"
3. Step 3: power-off the switch