BuntonHackman719

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

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

SW1#show vlan br

10  VLAN0010                         active

20  VLAN0020                         active

30  VLAN0030                         active

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

SW1#publish erase

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

[confirm]

[OK]

Erase of nvram: comprehensive

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 right after exiting setup mode, we run display vlan short once more. And even although the startup configuration was erased, the vlans are nonetheless there!

Switch#show vlan br

ten  VLAN0010                         active

20  VLAN0020                         active

30  VLAN0030                         active

The purpose is that this vlan and VTP info is truly 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 really want to get rid of this file. Do not variety "y" or "yes" just accept the defaults by hitting the return important. If you kind "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 success is by working on genuine Cisco gear, and by performing lab tasks over and over. Repetition is the mother of ability, and by really erasing your VLAN and VTP details by deleting the vlan.dat file from Flash, you'll be developing your Cisco capabilities to the point exactly where your CCNA and CCNP exam accomplishment is a certainty. discount quads for sale