VTP Pruning

VLAN Trunking Protocol (VTP) pruning is a feature that helps reduce unnecessary traffic in VLAN trunk links. When VTP pruning is enabled, it prevents VLAN traffic from being forwarded over trunk links to switches that do not have any ports assigned to that VLAN. This helps optimize network bandwidth and reduce unnecessary broadcast traffic.

VTP pruning works by dynamically creating a pruning eligible list of VLANs on each trunk link in the network. This list includes VLANs that have active ports on neighboring switches. When a switch receives a broadcast or multicast packet on a VLAN that is not on its pruning eligible list, the packet is dropped instead of being forwarded out of the trunk link.

To enable VTP pruning on a switch, the VTP mode must be set to server or transparent mode. VTP pruning is enabled by default on Cisco switches running IOS 12.1(13)E or later. It is important to note that VTP pruning should be used with caution, as it can potentially cause connectivity issues if not configured properly. For example, if a switch is not configured correctly and does not have the proper VLANs assigned to its ports, it may not receive traffic that it needs.