VTP Pruning
VTP pruning helps improve proper allocation and use of
network bandwidth by reducing unnecessary flooded traffic, such as broadcast,
multicast, unknown, and flooded unicast packets. VTP pruning is disabled by
default in Cisco switches. VTP pruning helps to send broadcasts only to those
trunk links that actually needs the information. For example, if switch A does not have a
port configured for VLAN 7, and broadcast is sent throughout VLAN 7, that
broadcast or traffic will not pass through the trunk link to switch A.
VTP pruning should only be enabled on VTP servers, all the clients
in the VTP domain will automatically enable VTP pruning. By default, VLANs 2 – 1001 are pruning
eligible, but VLAN 1 can’t be pruned because it’s an administrative VLAN. Both VTP
versions 1 and 2 supports pruning.
To enable VTP pruning on a Cisco IOS switch, you use the vtp pruning VLAN configuration
command. Once VTP
pruning is enabled, you can optionally configure a prune eligible list if you want
to limit the VLANs that can be pruned. The Example below demonstrates how
to enable VTP pruning on Switch.
VTP Pruning configuration :
SW1#config t
SW1(config)#interface Fa0/1
SW1(config-if)#switchport trunk pruning vlan 3-4
