Each switch can use one of three different VTP modes:
- VTP client mode – a switch using this mode can’t change its VLAN configuration. That means that a VTP client switch can’t create or delete VLANs. Received VTP updates are processed and forwarded.
- VTP server mode – a switch using this mode can create and delete VLANs. A VTP server switch will propagate VLAN changes. This is the default mode for Cisco switches.
- VTP transparent mode – a switch using this mode doesn’t share its VLAN database, but it forwards received VTP advertisements. You can create and delete VLANs on a VTP transparent switch, but the changes are not sent to other switches.
Consider the following example:
We have a simple network of three switches. SW1 is configured as VTP server. After the VLAN 5 is created on SW1, this switch will notify the connected switch (SW2) about the created VLAN. SW2 will receive the update but, since it uses the VTP transparent mode, it will not create this VLAN in its configuration. However, it will forward the VTP update to SW3. Since SW3 is configured as VTP client, it will process the update and create VLAN 5.