VTP database clearing

[wassim.kreidy]

Hi,

I think I read somewhere that turning off a switch will not clear the VTP database revision number.

Which means that if I am using a switch in a Lab environement and the revision number is increasing at a fast rate, connecting the switch (in VTP server mode) to my LAN will disrupt the network. Because of its high revision number it will overwrite all my VLAN information and basically stop my network operation!!

Can anyone confirm this (may be from previous experience)?

How can I clear my VTP database and reset the revsiion number if its not done when I power off the switch?

Thank you all.

[milan.kulik]

You are absolutely correct. The situation is even worse: If you connect a switch with higher revision number to the VTP domain it will overwrite the VTP database of the other switches even when it is a VTP CLIENT!!!

But there is a simple solution:

Just change the VTP domain name to something else (Null, e.g.) on the switch and then back to your VTP domain name. This will force the revision number to zero (check it by "sh VTP ..." command) and you can connect the switch to the network with no fear.

HTH,

Milan

[wassim.kreidy]

Hi Milan,

first thank you for the tip!

Do you know of another way (more direct) to clear the VTP database and the revision number (something like "Clear VTP database counter" command)

Anyway thanx for the info.

Regards

[milan.kulik]

Wassim,

I'm afraid there is no easy way of clearing VTP database. You can DISCONNECT your switch from the network, make it a VTP server, go to ena mode and

a) "clear VLAN ..." for each VLAN on CatOS based switch or

b) "vlan database" and "no VLAN ..." on IOS based switch

for each VLAN you want to clear. Every change will increase the revision number, of course.

One "brutal" way is to delete vlan.dat file from the flash of IOS based switch, but I would be very careful doing this.

Anyway, you should set the revison number to zero before connecting the switch to the network and the only way I know is changing VTP domain name force and back as I described already.

Best regards,

Milan