AthertonChambless420

CCNA and CCNP candidates who have their own Cisco property labs frequently e-mail me about an odd circumstance that occurs when they erase a switch's configuration. Their startup configuration is gone, as they expect, but the VLAN and VTP info is still there!

Sounds strange, doesn't it? Let's appear at an instance. On SW1, we run show vlan short and see in this abbreviated output that there are 3 additional vlans in use:

SW1#show vlan br

ten  VLAN0010                         active

20  VLAN0020                         active

30  VLAN0030                         active

We want to entirely erase the router's startup configuration, so we use the write erase command, confirm it, and reload with no saving the operating config:

SW1#compose erase

Erasing the nvram filesystem will remove all configuration files! Continue?

[confirm]

[OK]

Erase of nvram: complete

00:06:00: %SYS-7-NV_BLOCK_INIT: Initalized the geometry of nvram

SW1#reload

Program configuration has been modified. Save? [yes/no]: n

Proceed with reload? [confirm]

The router reloads, and after exiting setup mode, we run display vlan brief again. And even although the startup configuration was erased, the vlans are still there!

Switch#show vlan br

ten  VLAN0010                         active

20  VLAN0020                         active

30  VLAN0030                         active

The purpose is that this vlan and VTP details is actually kept in the VLAN.DAT file in Flash memory, and the contents of Flash are kept on a reload. The file has to be deleted manually.

There is a small trick to deleting this file. The switch will prompt you twice to ask if you actually want to get rid of this file. Don't variety "y" or "yes" just accept the defaults by hitting the return crucial. If you sort "y", the router attempts to delete a file named "y", as shown here:

Switch#delete vlan.dat

Delete filename [vlan.dat]? y

Delete flash:y? [confirm]

%Error deleting flash:y (No such file or directory)

Switch#delete vlan.dat

Delete filename [vlan.dat]?

Delete flash:vlan.dat? [confirm]

Switch#

The best way to prepare for CCNA and CCNP exam good results is by working on true Cisco equipment, and by performing lab tasks over and more than. Repetition is the mother of ability, and by genuinely erasing your VLAN and VTP information by deleting the vlan.dat file from Flash, you are going to be developing your Cisco expertise to the point exactly where your CCNA and CCNP exam accomplishment is a certainty. motor bikes