VLAN Database

[typesh]

Hey everyone,

Just wondering about backing up VLAN databases. I just got my hands on Packet Tracer and I'm testing it out by doing some small configs (it's a really cool program so far!).

In one situation I created a bunch of VLANS and assigned some ports to each VLAN. I did a 'show run' but it only shows the running-configuration and has no VLAN information. After some research on the internet I figured out : The VLAN configuration is stored in the vlan.dat file, which is stored in nonvolatile memory. (I found that on the Cisco site)

I don't have the equipment to try this out (and I'm not sure if it can be done in Packet Tracer), but if you copy the vlan.dat file into another switch, will all your VLANs appear on the new switch?

Thank you.

[lammle]

Yes, you can save/backup and copy the vlan database.

This is all over my book. No need to search the Cisco web site.
Also, it is a CCNA objectives, hence it being all over my book.

You need to study VTP in my book and how it uses this vlan database. Very important stuff!

Cheers!
Todd Lammle

[typesh]

Thanks for your reply Todd! I had a look at Chapter 9 once more. I think my question didn't really say what I was really thinking. I understand that VTP will replicate the VLAN database to other switches across the network which are configured with the correct domain name ect... but let's say I only have one switch. With my one switch I configure a bunch of VLANS and assign ports to them. Then I backup my vlan.dat to a TFTP server. This way, in case my switch ever dies I can just buy a new one, load in the vlan.dat and have all my VLANS up and running again without having to reconfigure them. I was thinking along the lines of when we were backing up the IOS to the TFTP Server in Chapter 5. If we had other switches in the network, I could just configure my new switch to read the VLAN database from another switch that was in Server Mode. I guess I was just wondering about the manual way of doing things when there is only one switch in the network.

[lildeezul]

Cisco is really trying to phase out the vlan database.. Try to get used to creating vlans from global config mode...( which is simplier, in my opinion)

but the vlan database is good to know, just make sure you focus more on the global way to configure them

[pconlan]

Cisco is really trying to phase out the vlan database.. Try to get used to creating vlans from global config mode...( which is simplier, in my opinion)

but the vlan database is good to know, just make sure you focus more on the global way to configure them

You are right Cisco has changed the way the VLAN database is configured. You should no longer use the vlan database command and the associated command sub structure. However, the separate VLAN database file is still created and stored in flash. Which can be backed up and stored to a switch or switches. When you use the global config commands to modify/add/delete a vlan or VTP parameter you are still changing the VLAN database, and the vlan.dat file is being modified.

The biggest miss understanding with this topic is when you start talking about the "interface vlan". This command creates what is called a switched virtual interface (SVI). An SVI is not stored in the vlan.dat and is not a required component of a vlan. On a layer 2 switch you can only use one SVI, this SVI is used to manage the switch. Many people think the SVI that is used must be interface vlan 1 but it does not. You can create more than one SVI on the switch, but only one can have an IP address.
On a multilayer switch however, you can create an SVI for every vlan. The SVI serves as the layer 3 gateway for each vlan and the connection to the layer 3 routing process. This is required for intervlan routing. If you configure a vlan on a multilayer switch the vlan is created in the vlan database and an SVI is not created. If you first create an SVI for a vlan, then the vlan is not created in the vlan database. You must create both components for routing.
An SVI on a multilater switch is still different and not the same as a routed port. You can make a single physical port on a switch a routed port using the no switchport command. A routed port has the same characteristics as a port on a router. It is separately connected to the route processor and is not a part of any one vlan. Routed ports are useful for connecting the switch to a single server or to a firewall to go out of the network.
Hope this helps everyone. Let me know.
Pat

PS. I am done with all the edits on my book, and it will be going through the layout process and going to print soon. Should hopefully be sometime in April still. Crossing my fingers!

[typesh]

You are right Cisco has changed the way the VLAN database is configured. You should no longer use the vlan database command and the associated command sub structure. However, the separate VLAN database file is still created and stored in flash. Which can be backed up and stored to a switch or switches.
PS. I am done with all the edits on my book, and it will be going through the layout process and going to print soon. Should hopefully be sometime in April still. Crossing my fingers!

Hey guys,

Thanks a lot for your explanations. That clears it up for me.
I was wondering about backing up that vlan.dat and using it for recovery.
I guess if you're only using only one small 1 switch it wouldn't be much work to set up a few VLANS anyway.