WilburBraley849

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

Sounds odd, does not it? Let's appear at an instance. On SW1, we run show vlan short and see in this abbreviated output that there are three further vlans in use:

SW1#display vlan br

10  VLAN0010                         active

20  VLAN0020                         active

30  VLAN0030                         active

We want to completely erase the router's startup configuration, so we use the write erase command, confirm it, and reload with out saving the running config:

SW1#create erase

Erasing the nvram filesystem will get rid of 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 immediately after exiting setup mode, we run show vlan short once more. And even though the startup configuration was erased, the vlans are still there!

Switch#show vlan br

ten  VLAN0010                         active

20  VLAN0020                         active

30  VLAN0030                         active

The reason is that this vlan and VTP information is really 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 little trick to deleting this file. The switch will prompt you twice to ask if you genuinely want to get rid of this file. Do not sort "y" or "yes" just accept the defaults by hitting the return essential. 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 greatest way to prepare for CCNA and CCNP exam good results is by operating on true Cisco gear, and by performing lab tasks over and over. Repetition is the mother of skill, and by truly erasing your VLAN and VTP info by deleting the vlan.dat file from Flash, you are going to be constructing your Cisco capabilities to the point where your CCNA and CCNP exam good results is a certainty. used car value