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
Links:
https://www.cisco.com/c/en/us/support/docs/lan-switching/vtp/10558-21.html