Naming a VLAN
With “show vlan brief” , we’ll see all VLANs that we created earlier, plus VLAN32 which I just left empty.

So we have a couple of empty VLANs here. We have ports 2 and 4 in VLAN24.
We can give names to VLANs specially when we have lots of them because it would be easier to find them while troubleshooting.
To do so, we need to go to the VLAN config mode.

And then for example we’ll go to VLAN 45
And it’ll give us lots of options which we normally don’t use.

Now we give it a name.

Now look at the result:

Erasing a Config and Initializing a Cisco Switch again:
We normally don’t do it! But doing so will delete any configuration and it would be like a new Switch!
To look at the current config, we have to type “show run”



As you can see, when you look at the config where the ports are, that interfaces which are in the default VLAN, the default VLAN is not indicated.
But if they are in a non-default VLAN, you’ll see “switchport access vlan” command. Now to erase the config, we can put in “wr er” which is a short from for “write erase”

You’re erasing a NV memory, which is the memory that is not lost on a reload. So we are basically are getting rid of everything.

It’ll ask for confirmation ( which means it’s serious) and if we hit ENTER, everything will be GONE!!!

We can do a “reload” to see if everything is really gone. ( we say NO to save )

Then you’ll see lots of lines… and in between, you’ll see this :

This is what happens when a very important file from flash is being loaded. As long as you continue to see that, you’re OK. If it stops for a long time, it means that there is a boot problem. But it didn’t happen here and at the end we can see “ File uncompressed and installed”

Then it gives you some information about the hardware you’re on… and other informations.

POST means “power On Self Test”. The switch is running this test to see if it’s worth continuing to boot up. For example if there is an environmental issue (for example if Fan is not working), then the switch will tell you it’s not worth booting up!
But here we don’t have any issue and the process is complete.

Now we see a message about “cryptographic features” and it’s a pretty serious message. Because it says that by using this device, you’re compying with some laws and regulations.
The important part is : “ Delivery of Cisco cryptograohiic products does not imply third-party authority to import , export, distribute or use encryption.”Because Cisco parts are not allowed to ship to some countries.
At the end, there is a Yes/No question about System Configuration Dialog.

If we say Yes, the we’ll enter “Setup Mode” and it’ll ask you a Yes/No question on every step. So as a biginner we’d better say No.
If say No, it’ll drop us off right at the prompt. Now the host name is gone.

If we do “show run” , it’s going to build it and you see the hostname “switch”

But you’ll notice that everything we did on 2 and 4 is gone.

Also the lab commands that we previously wrote, are gone too.

Because nothing is under the “line con 0 “ which means there is no configuration of cosole port at all!
So everything seems to be erased.
Now we do “show vlan brief” and surprisingly those VLANs are still there!

Why ?
Let’s go to the directory.

All of the VLAN information that you see appear in “show vlan brief”, is contained in “vlan.dat” and NOT in NV memory. So we have to erase that file as well if we want to totally initialize a Cisco switch.
We do it by “del vlan.dat”

Now if say Y, then it’ll think that we want to delet a file in flash named Y !! so it’s better to hit ENTER instead.

Now if do a reload and repeat all the steps we did, we’ll see that those VLANs are gone.
