Propagating VLAN Information with VTP
How to add a new switch to an existing VLAN

The configuration revision number is the only criterion used when determining if a switch should keep its existing VLAN database or overwrite it with the VTP update sent by another switch in the same domain with the same password. Therefore, when a switch is added to a network it is important that it does not inject spurious information into the domain.

CAUTION:

If a new switch was at one time attached to another network, it is feasible that it contains a vlan.dat file in Flash and that its configuration revision number is higher than that of other VTP servers in the VTP domain to which it is being added. If no VTP domain was explicitly configured on the switch, when connected to the network, the new switch is able to derive the VTP domain name from any VTP update it sees. If there is no password on the domain and if the new switch is in server mode (default), its VLAN information can overwrite the VLAN database on other switches in the VTP domain.

The How to Add a Switch table explains the steps to take to add a new switch to the network. It is very critical to VLAN stability to add a switch in this manner.


Lab Activity

e-Lab Activity: Configuring VLANs and VTP

In this lab, the student will configure trunking, and VLANs. Also the student will verify the VTP and VLAN status on the switch.