VTP Advertisements

VTP uses various types of messages or advertisements to allow VTP enabled switches to exchange VLAN information. These advertisements fall into the following categories:

Summary Advertisements

• These contain the VTP domain name, the current revision number and other VTP configuration details
• Summary advertisements are sent:
  • every 5 minutes by a VTP server or client to inform neighboring VTP enabled switches of the current VTP configuration revision number for its VTP domain
  • Immediately after a configuration has been made

Subset Advertisements

• A subset advertisement contains VLAN information
• Subset advertisements are sent whenever:
  • a VLAN is created or deleted
  • a VLAN is activated or suspended
  • the name of a VLAN is changed
  • the MTU of a VLAN is changed
  • a switch receives a request advertisement message

Request Advertisements

• When a request advertisement is sent to a VTP server in the same VTP domain, the VTP server responds by sending a summary advertisement and then a subset advertisement
• Request advertisements are sent when:
  • The VTP domain name has been changed
  • The switch receives a summary advertisement with a higher configuration revision number than its own
  • A subset advertisement message is missed for some reason
  • The switch has been reset