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Community Member

lost vlans

Hi everybody,

My customer had a problem yesterday.

In fact, he has 1 Catalyst 4507 and suddenly the Catalyst 4507 lost his vlan configuration (only the vlans configuration).

The catalyst 4507 and the others switches connected are configured as VTP server but with a vtp password.

On the 4507 IOS there is no vlan.dat file on the flash.

So, I don't understand what happened.

Anyone has an idea what could be the reasons ?

Thank you for your help.


Re: lost vlans

Hi Friend,

Can you confirm if 4507 is running redundant supervisor engines and did the active went down and standby tookover?



Community Member

Re: lost vlans

Hi Ankur,

Yes, there are two supervisor engines and I suspect that the standby supervisor took over.

Do you think that there is a relationship ?


Community Member

Re: lost vlans


what is the IOS version of 4507 ? (bug?)

when the behaviour occurs, is there an insertion of new switches ?


Cisco Employee

Re: lost vlans

The VLAN database is not stored on the flash, it is stored on:

Directory of cat4000_flash:/

1 -rw- 676 vlan.dat

Don't know if you've taken a look there.

Usually something like that would happen if a new switch, with a higer VTP Configuration Revision, but an empty vlan database, is connected into the network.

Community Member

Re: lost vlans

The IOS version of the two sup are 12.1(19)EW.

I don't think that there is a bug with this IOS version but I'm not sure.

My customer said me that there wasn't any new switch connected.

What do you think if I propose to configure all the switches in VTP transparent mode ?

At the moment there are in VTP server with a VTP password.

Thank you by advance if you have any other suggestion.


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