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Cisco Vlan Query

Hi Experts,

Can someone explain to me why I can't see the vlan 100 and name user-vlan in the show run in the first attachment, however I can see it when I do a show vlan brief? However, the second attachment I can see the vlan in the show run/configuration.

The reason why I ask is because when I do a copy the configs from a TFTP to the switch in the first case the vlan 100 and name user-vlan won't be copied to the switch because its not in configuration, whereas in the second case the vlan configurations will be picked up and copied to the switch because its in seen in the configurations

Cheers

Carlton
2012-03-31--12-45-54-164--DLS1-4.txt
2012-03-31--13-37-01-861--DLS1-4.txt

Nayyar HH (CCIE RS)

There are two methods for vlan configuration; in the vlan database mode and in the config mode;

The first switch looks like the VLAN is configured in VLAN database

example;

vlan database
vlan 100
apply
exit

config t
interface vlan 100
ip address x.x.x.x y.y.y.y
no shut

end
wr mem

The second looks like the VLANs is configured in the config mode

config t

vlan 100

int vlan 100
ip address x.x.x.x y.y.y.y
no shut

end

wr mem

So if you were scripting configuration deployments you would to include appropriate config for vlan configuration

cpatte7372

ASKER

Nazsky,

Thanks for responding.

I used conf t in both cases....

Nayyar HH (CCIE RS)

Wierd .. are you using real switches or emulation software?

cpatte7372

ASKER

Very wierd....

Real switch.

It didn't do a write mem. Would that make any difference?

cpatte7372

ASKER

Actually, it shouldn't make any difference because the vlan is shown with whe show vlan brief command

Jimmy Larsson, CISSP, CEH

Even if you do "conf t", in some switches the vlans are stored in a separate vlan database, not in running-config. It´s just the way it is. Look for a file called something like flash:/vlan.dat, that contains the vlan database in switches that doesnt store them in running config.

Best regards
Kvistofta

Nayyar HH (CCIE RS)

pls post a "show version" output

cpatte7372

ASKER

Kvistofta, Nazsky,

I will post the show version in a bit. However, I was wondering if the fact that the running config where there is not vlan info might because on that switch I configured vtp mode transparent, vtp domain switch and vtp pass ccnp?

Just a thought

Jimmy Larsson, CISSP, CEH

vtp mode transparent means that the switch doesnt care about vtp information. All vtp-packets coming into the switch is being passed to other switches but the content of the vtp-packets are not being read. That means that for a vtp transparent-switch you need to configure all vlans by hand, locally. And as I said above, either they stay in the running/startup-config or in the separate vlan-database. In both cases you configure (create) vlans in config-mode.

Best regards
Kvistofta

Nayyar HH (CCIE RS)

The vtp configuration should not cause the symptoms experienced - to me it appears like a software cosmetic issue/bug than anything

cpatte7372

ASKER

Experts,

This is the answer:

Hello Carlton,

What you are seeing here is caused by your VTP mode setting. If the VTP mode is set to Transparent then the VLANs are being displayed in the running-config in addition of being also stored in the vlan.dat file. If the VTP mode is either Server or Client, the VLANs are only stored in the vlan.dat file and do not appear in the running config. As you can see, your second configuration obviously contains the vtp mode transparent command.

Best regards,

Peter

Nayyar HH (CCIE RS)

Any references/links to Cisco documentation that this is the actual behavior?

Jimmy Larsson, CISSP, CEH

cpatte7372: That is so untrue. A VTP-transparent switch does NOT get any vlan-information from VTP.

/Kvistofta

cpatte7372

ASKER

Is there any experts that agree with Kvistofta?

ASKER CERTIFIED SOLUTION

Jimmy Larsson, CISSP, CEH

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cpatte7372

ASKER

Kvistofta

I guess I agree with the Cisco statement. However, the main issue was why the vlan information isn't stored/displayed in the running config when you do a show run?

Jimmy Larsson, CISSP, CEH

As I said, some switches and some software-versions stores the vlan-information in a separate vlan-database on flash, other stores them in startup-config. It´s by design. Why? I guess you will never know unless you find the right developer at Cisco. :-)

Best regards
Kvistofta

cpatte7372

ASKER

Cheers mate..