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