Switches may not be sharing VLAN Trunking Protocol (VTP) messages for several reasons. They might be in different VTP domains, preventing them from exchanging information. Additionally, if one or more switches are set to "client" mode while others are in "transparent" mode, the clients will not share VTP messages with the transparent switches. Lastly, issues such as trunk link misconfigurations or mismatched VTP versions can also hinder message sharing.
Layer 2 multicast. vtp is stopped at the router.
For VLAN Trunking Protocol (VTP) to function correctly, all switches in the VTP domain must be configured with the same VTP domain name. Additionally, at least one switch must be set to VTP server mode to create and propagate VLAN information, while other switches can be configured as clients or transparent modes. Proper trunking must also be established on the links connecting the switches to facilitate the transmission of VTP advertisements.
server mode Answer by: sean_zhank
Transparent mode
2
Three VTP parameters that must be identical on all switches to participate in the same VTP domain include domain name, domain password, and version number. VTP stands for VLAN Trunk Protocol. The answer can be found at http://www.ccna4u.org/2011/06/ccna-3-chapter-4-2011-v4-0-answers-100.html
All VLANs that are configured on this switch will be sent to all other switches in the same VTP domain. Adding this switch to the network will cause no disruption in the VTP domain operations if the rest of the switches in the same domain have a higher configuration revision number.
Configure the VTP mode of the switch to transparent. Configure the switch with the same VTP domain name as other switches in the network.
In very simple language. Cisco switches can be configured in VTP Server, transparent or client mode. VTP server is the default mode in most everyday switches. The switch must be in server mode in order to create,add, delete VLAN's in the same domain. If I am using more than one switch, the one with the lowest MAC address is the one I would use to be my STP. The other switch would be in CLIENT mode (my preference).
VTP server mode and VTP transparent mode.
Client
The VTP domain cannot be modified.