vtp advertisements

Answered Question
Jun 15th, 2008

hi every body!

i have some weird questions about vtp advertisements.

Let say we have two switches: sw1 and sw2

sw1 is vtp server,sw2 is vtp client

sw1 has config#= 2,domian name: cisco

sw1 and sw2 are sychronised.

now a third sw3 with domain name: null and config# 4 is added to the network.

Will sw1(server) will process updates from sw3?

To put simply is it possible for a server with a domain name cisco to receive and process vtp updates from a switch with domain name null ?

thanks a lot !

I have this problem too.
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Correct Answer by hsitar007 about 8 years 5 months ago

I tested with some more configurations and here is what i got:

Any new switch(VTP-SERVER/VTP CLIENT) added to the existing network with null domain and higher config# would get updated with the existing domain name and it would change to the existing Config# in the network even if it is less.

In your config sw3 would be updated by Sw1 regardless of who has higher config# because sw3 has a null domain name. sw3 would also get a domain name of cisco.

Its all tested.

Regards,

Ratish

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mahmoodmkl Sun, 06/15/2008 - 16:18

Hi

I think if the domain names are mis-matched there is no effect on the updates recieved from the new switch.If the domain name is same then its going to update its database.

Thanks

Mahmood

merryllem Sun, 06/15/2008 - 20:22

I agree with what Mahmood. I do however, think that it is good practice to change the mode of the switch you want to add to "transparent"

francisco_1 Mon, 06/16/2008 - 04:34

also something to understand on the client side is if you have a vtp client switch on the network, that vtp client switch do not have to have the VTP domain name configured. if not configured the client will assume it should use the VTP domain name in the first received VTP update. However the clinet does need one small bit of configuration namely, the VTP mode, as configured with the vtp mode global configuration command.

sarahr202 Wed, 06/18/2008 - 05:20

hi every body!

Thanks for all of you who responded to my post. However my question remained unresolved.Let me repeat my question in short.

If a vtp sever switch with domain name "cisco" ,config # 3, receives a summary addverstisement from newly introduced switch with domain name "null" ,config # 6,would server switch will change its domain name from cisco to null? would newly introduced switch overwrite the server's switch vlan configuration with its own?

thanks alot and wonderful day !

hsitar007 Wed, 06/18/2008 - 05:37

Answer is no. But the newly introduced switch would be updated with domain name 'cisco' and its config reg# would become 3 if the new switch is vtp client. And if it is a vtp server then nothing would change.

Hope this helps.

Ratish

foxbatreco Mon, 06/16/2008 - 06:30

No. The domain names must match for the switches in question to get synchronised with updates via vtp.

U can use the sh vtp counters on the switch to see the counters thru each of the trunk ports involved if it is getting any updates.

The domain names must match.

Pls rate/mark if this helps!!!

Ibbywannit Mon, 06/16/2008 - 06:51

Also remember to check the revision number of the switch that you are adding to the network even if you place it into client mode. The revision number can wreck havoc to your current switch configuration. I agree with the earlier post of placing the switch into transparent mode - or if you want the switch in client mode set it to transparent 1st and then to client - this will clear the revision number.

hsitar007 Tue, 06/17/2008 - 05:27

Hello All,

If sw3 is a client then sw1 would update its domain name and vlan information to sw3 but if it is a server then it would remain intact without any change. sw3 would not update sw1 in any case.

HTH

Ratish

Correct Answer
hsitar007 Wed, 06/18/2008 - 06:11

I tested with some more configurations and here is what i got:

Any new switch(VTP-SERVER/VTP CLIENT) added to the existing network with null domain and higher config# would get updated with the existing domain name and it would change to the existing Config# in the network even if it is less.

In your config sw3 would be updated by Sw1 regardless of who has higher config# because sw3 has a null domain name. sw3 would also get a domain name of cisco.

Its all tested.

Regards,

Ratish

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