Passing Cisco's CCNA and CCNP Exams: The VLAN.DAT File
By: Chris Bryant, CCIE #12933
CCNA and CCNP candidates who have their own Cisco home labs often email 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 information is still there!
Sounds strange, doesn't it? Let's look at an example. On SW1, we run show vlan brief and see in this abbreviated output that there are three additional vlans in use:
SW1#show vlan br
10 VLAN0010 active
20 VLAN0020 active
30 VLAN0030 active
We want to totally erase the router's startup configuration, so we use the write erase command, confirm it, and reload without saving the running config:
SW1#write 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
System configuration has been modified. Save? [yes/no]: n
Proceed with reload? [confirm]
The router reloads, and after exiting setup mode, we run show vlan brief again. And even though the startup configuration was erased, the vlans are still there!
Switch#show vlan br
10 VLAN0010 active
20 VLAN0020 active
30 VLAN0030 active
The reason is that this vlan and VTP information 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's a little trick to deleting this file. The switch will prompt you twice to ask if you really want to get rid of this file. Don't type "y" or "yes"; just accept the defaults by hitting the return key. If you type "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 success is by working on real Cisco equipment, and by performing lab tasks over and over. Repetition is the mother of skill, and by truly erasing your VLAN and VTP information by deleting the vlan.dat file from Flash, you'll be building your Cisco skills to the point where your CCNA and CCNP exam success is a certainty.
|
About The Author
Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (www.thebryantadvantage.com), home of FREE CCNA and CCNP tutorials, The Ultimate CCNA Study Package, and Ultimate CCNP Study Packages. Video courses and training, binary and subnetting help, and corporate training are also available.
For a FREE copy of his latest e-books, "How To Pass The CCNA" or "How To Pass The CCNP", send a request to chris@thebryantadvantage.com today !
|
This article was posted on November 03, 2005
DVD Detective: The Best Environmental Documentaries by Farr
Next to family and clean water, movies are my focus and my passion. In my writing and speaking engagements, I serve as a sort of quality filter for movie lovers, sifting intelligent, rewarding titles from the enormous volume of DVD titles in the marketplace.For our friends at Waterkeeper, I’m doing a series of articles highlighting films that celebrate the beauty of our natural world, and, dir. . .
Return to Index
UK
Financial Services
Sub-categories: Accounting
| Banks
| Building
Societies | Corporate
Finance | Credit
Services | Currency
Services | Debt
Collection | Directories
| Factoring
| Financial
Consultants | Fund
Management | Independent
Financial Advisors | Information
Services | Insurance
| Leasing
| Merchant
Services | Offshore
Services | Organisations
| Personal
Finance | Publications
| Regulation
| Socially
Responsible Investment | Stockbrokers
| Taxation
Article Index: 1
- 2 - 3
- 4 - 5
- 6 - 7
- 8
World
Financial Services
Sub-categories: Associations
| Automobile
Buying and Financing | Banking
Services | By
Region | Cash
Flow | College
Financing | Commercial
Lending | Computer
Financing | Cooperatives
| Credit
and Collection | Directories
| Education
and Training | Employment
| Field
Service Companies | Financial
Consultants | Financial
Planning | Freelancer-Contractor
Services | Holding
Companies | Information
Services | Insurance
| Investment
Banks | Investment
Services | Leasing
Services | Loans
| Marketing
and Advertising | Medical
Billing | Merchant
Services | Mortgages
| News
and Media | Offshore
Services | Payroll
Services | Surety
Bonds | US
Government Financial Sites | Venture
Capital | World
War II Dormant Accounts
Get "IN TO" Vicky's
"rr-tit-calls" (Vicky's a Yorkshire Lass)
Latest News & Previews
Fall
Is In The Air! What Does That Mean? FOOTBALL SEASON!
I just hate it! To make matters worse hubby is home on sick
leave due to his own football injury tossing the dogs toy football and trying
to beat the dog across the yard for it, needless to say those groin muscles
will be out of commission for a while. Lying around with his ice bag the first
day watching soaps with me was enough to make him nuts! Then day two at 2:00
pm, time for “The Young and The Restless” he hides the stupid remote!
I’m going insane tearing the house apart... this is my favorite soap!! He
can’t do this to me!! The whole time I’m going nuts looking for the
remote, he i. . .
Getting
Paid To Drive
There seems to be a never ending fascination to the notion
that some people get paid to drive their cars. While it is true that a few
lucky people are able to do this, the entire field of paid to drive
opportunities has changed dramatically over the last few years.The get paid to
drive concept was at the height of its popularity during the Internet bubble
of the late 1990s. Roadside advertising was near capacity leaving the many
companies that wanted to advertise their service or product to those driving
in their cars without a place to do so. At this time, billboard and other
traditional a. . .
History
of the Guitar
It is very difficult to trace a line back to the exact birth
of the instrument we know as the guitar today, as there is a lot of myth and
uncertainty surrounding its origins. This is mainly due to the fact there have
been a number of similar instruments throughout the ages. Many historians
claim the guitar originated at various points in time. Some believe the guitar
in its earliest form dates back some 4000 years, however no-one really knows
for sure. This is due to a number of artworks that depict guitar-like
instruments being used at various times throughout history. Many ancient
Egyptia. . .
|
