VTPv1 and VTPv2 use 4 types of messages:
- Summary Advertisement: this message comes from the Server and Clients every 5 minutes and after each update to the VLAN database. This message includes the VTP domain name, revision number, identity of the last updater, time stamp of the last update, MD5 sum computed over the contents of the VLAN database, and the VTP password, and the number of subset advertisements following the Summary Advertisement.
- Subset Advertisement: This message is generated when the VLAN database is updated, it is sent out via the Server and clients in the VTP domain. These advertisements carry the full VLAN database.
- Advertisement request: This message is sent from Servers or clients to VTP neighbors to request the contents of the complete VLAN database or a portion of it. These messages are sent when a Client switch is restarted, when a switch enters client mode, or when a server or client switch receives a summary advertisement with a higher revision number.
- Join: This message is sent out of the Servers or Clients every 6 seconds if VTP pruning is active. These messages contain a bit field that indicates whether normal VLANs configured are active or unused.
Currently there is no documentation released for VTPv3 messages.