Understanding Vtp Pruning - Cisco WS-C2948G-GE-TX Configuration Manual

Understanding How VTP Version 1 and Version 2 Work

Understanding VTP Pruning

Note Enabling VTP pruning on a VTP version 3 switch enables pruning only on the switch that you enable it
on. VTP pruning is not propagated as it is with VTP version 1 and VTP version 2.
VTP pruning enhances network bandwidth use by reducing unnecessary flooded 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.
Make sure that all devices in the management domain support VTP pruning before enabling it.
Figure 9-1
Switch 4 are assigned to the Red VLAN. A broadcast is sent from the host that is connected to Switch 1.
Switch 1 floods the broadcast and every switch in the network receives it even though Switches 3, 5, and
6 have no ports in the Red VLAN.
Figure 9-1
Figure 9-2
Switch 1 is not forwarded to Switches 3, 5, and 6 because traffic for the Red VLAN has been pruned on
the links indicated (port 5 on Switch 2 and port 4 on Switch 4).
Catalyst 4500 Series, Catalyst 2948G, Catalyst 2948G-GE-TX, and Catalyst 2980G Switches Software Configuration Guide—Release 8.2GLX
9-4
shows a switched network without VTP pruning enabled. Port 1 on Switch 1 and port 2 on
Flooding Traffic without VTP Pruning
shows the same switched network with VTP pruning enabled. The broadcast traffic from
Chapter 9 Configuring VTP
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