VTP Question

[ianwalker79]

This is probably a daft question, but here goes... I've configured two new 3750s, all seems ok. The query i have is that after I set the vtp mode to client and the domain, then reload the config the vtp settings revert back to server and NULL as the domain. Why do the vtp settings keep reverting to the default?

Am I right in saying that so long as the vtp revision is set to zero there will be no problems when connecing these switches to the network as the other switches all have a higher revision?

Many thanks.

[royalblues]

Hi Friend,

THe VTP information is not stored in the NVRAM when it is in the client mode and hence when you reload the switch the settings go back to the default.

In VTP client mode, VLAN configurations are not saved in NVRAM. If you have a valid trunk between the switches the VTP server would inturn update the client VLAN database

http://www.cisco.com/univercd/cc/td/doc/product/lan/c3550/12113ea1/3550scg/swvtp.htm#wp1205076

Whenever you want to add a new switch make sure the VTP revision number of the new switch is less than the VTP revision number among other switch groups in that domain.

The revision number can be made zero in 2 ways

Set the domain to anything bogus and change it back to the required.

Change the mode of the switch to transparent and back to client

HTH, rate if it does

Narayan

[ianwalker79]

Hi,

Many thanks for the reply. Just to confirm though - is it normal behaviour for the switch to lose the domain settings and change from cliwnt to server when it is reloaded?

i thought that once the domain info has been entered it should retain this information? Do I have to run a command to save the vtp configuration?

Or would this not be a problem if it was already connected to the network and was receiving vtp updates?

Thanks again.

[network.king · Accepted solution]

Hi

It is not a normal behaviour of the switch to lose the domain settings and change from client to server when reloaded.

As said by narayan, only the vlan configurations are not stored in NVRAM , but all the VTP configurations would be stored in the NVRAM and as writing the other commands into NVRAM , the same " Write Mem " is used for saving the VTP configs in NVRAM.

Hope this helps

regards

vanesh k

[glen.grant]

It should not change from client to server over a reboot . You are saving the config when you do it correct, with a write mem command ? If you do a show startup and it says that vtp mode is client and the vtp domain name is correct then it has to load those settings as that is where the initial config is loaded from

[ianwalker79]

I tried again, and did a write mem, the settings were still lost. I was making the changes in global config mode.

I then tried it by running 'vlan database' in priveleged mode, and setting the vtp settings there, followed by a write mem. After the reload the settings had remained as I had set them so it seems this is resolved....

Any ideas why the settings have stuck when using 'vlan database' rather than global config? did i need to run something other than write mem?

When entering vlan database a message displayed on the console stating that it is no longer the preferred method of changing vlan/vtp settings..

Many thanks

[glen.grant]

I think the only way they show up in the global config is when the switch is setup as transparent mode . If running client mode you need to do as you did and put into the vlan database . IT will not show up in the config in this mode only transparent mode . Not sure why they made it this way . It also makes it a pain in the butt in that to really have a backup of the switch you need to backup the config file and the vlan.dat file . An advantage of the older catos operating system you didn't have to worry about this .