Ccna / Ccnp Home Lab Tutorial:  The Vlan.dat File

Ccna / Ccnp Home Lab Tutorial: The Vlan.dat File

Ccna / Ccnp Home Lab Tutorial: The Vlan.dat File

CCNA and CCNP applicants who’ve their own Cisco house labs often email me personally about an odd circumstance that occurs if they erase a switch’s construction. Their startup construction is fully gone, as they anticipate, however the VLAN and VTP details is still there!

Sounds strange, does it not? Let’s look at a good example. On SW1, we work show vlan short and discover in this abbreviated result there are three extra vlans used:

SW1#show vlan br

10 VLAN0010 active

20 VLAN0020 active

30 VLAN0030 active

You want to totally erase the router’s startup configuration, thus we utilize the write erase order, confirm it, and reload without keeping the running config:

SW1#write erase

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

[confirm]

[OK]

Erase of nvram: complete

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

SW1#reload

System construction has been modified. Conserve? [yes/no]: n

Proceed with reload? [confirm]

The router reloads, and after exiting setup mode, we run show vlan short again. And although the startup construction was erased, the vlans remain there!

Switch#show vlan br

10 VLAN0010 active

20 VLAN0020 active

30 VLAN0030 active

The reason is that vlan and VTP information is in fact kept in the file in Flash memory, and the contents of Flash are continued a reload. The document needs to be deleted manually.

There’s just a little trick to deleting this file. The change will prompt you twice to question if you actually want to eliminate this document. Don’t type “y” or “yes”; simply acknowledge the defaults by striking the return key. In the event that you type “y”, the router tries to delete a document named “y”, as proven here:

Switch#delete

Delete filename []? y

Delete flash:y? [confirm]

%Mistake deleting flash:y (Zero such document or directory)

Switch#delete

Delete filename []?

Delete flash:? [confirm]

Switch#

The simplest way to plan CCNA and CCNP exam success is by focusing on real Cisco equipment, and by performing lab tasks again and again. Repetition is the mom of skill, and by really erasing your VLAN and VTP info by deleting the document from Flash, you will be building your Cisco abilities to the stage where your CCNA and CCNP examination achievement is a certainty.

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