A VLAN data file residing in Flash prevents the Catalyst fixed configuration switch series from returning to factory defaults after a write erase and reload.
Catalyst Fixed Configuration Switches 2900XL, 2940, 2950, 2955, 2970, 3500 XL, 3550 and 3750 still have VLAN data after issuing the write erase (or erase startup-config) and reload commands. This occurs unless the VLAN configuration file in Flash is deleted.
To delete the VLAN data and set the switch back to the factory defaults, before reloading issue the delete flash:vlan.dat command.
Note: To save the configuration when reloading, select no if prompted. Answering yes causes the data to be written back to NVRAM.
This is a sample output:
Cat2950#write erase Erasing the nvram filesystem will remove all files! Continue? [confirm]y[OK] Erase of nvram: complete Cat2950# Cat2950#delete flash:vlan.dat Delete filename [vlan.dat]? (Press enter here) Delete flash:vlan.dat? [confirm]y Switch# Switch#reload System configuration has been modified. Save? [yes/no]: n