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| 2.8 |  | VTP Configuration and VTP Pruning |
| 2.8.6 |  | Default behavior of a switch |

The default behavior of a switch is to propagate broadcast and unknown packets across the network. This behavior results in a large amount of unnecessary traffic crossing the network.

VTP pruning increases bandwidth efficiency by reducing unnecessary flooding of traffic, such as broadcast, multicast, unknown, and flooded unicast packets. VTP pruning increases available bandwidth by restricting flooded traffic to those trunk links that the traffic must use to access the appropriate network devices. By default, VTP pruning is disabled.

In a switched network that does not have VTP pruning enabled, broadcasts will be sent to switches that do not need to receive them. Port 1 on Switch 1 and Port 2 on Switch 4 are assigned to the green VLAN. A broadcast is sent from the host connected to Switch 1.

Switch 1 floods the broadcast and every switch in the network receives this broadcast, even though Switches 3, 5, and 6 have no ports in the green VLAN.

With VTP pruning enabled, the broadcast traffic from Switch 1 is not forwarded to Switches 3, 5, and 6 because traffic for the green VLAN has been pruned on Port 5 on Switch 2 and Port 4 on Switch 4.