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VTP pruning is disabled in the switched network. Port 1 on Switch A and Port 2 on Switch D are assigned to
the Red VLAN. If a broadcast is sent from the host connected to Switch A, Switch A floods the broadcast
and every switch in the network receives it, even though Switches C, E, and F have no ports in the Red VLAN.
Figure 1: Flooding Traffic without VTP Pruning
VTP pruning is enabled in the switched network. The broadcast traffic from Switch A is not forwarded to
Switches C, E, and F because traffic for the Red VLAN has been pruned on the links shown (Port 5 on Switch
B and Port 4 on Switch D).
Figure 2: Optimized Flooded Traffic VTP Pruning
Enabling VTP pruning on a VTP server enables pruning for the entire management domain. Making VLANs
pruning-eligible or pruning-ineligible affects pruning eligibility for those VLANs on that trunk only (not on
all switches in the VTP domain).
VTP pruning takes effect several seconds after you enable it. VTP pruning does not prune traffic from VLANs
that are pruning-ineligible. VLAN 1 and VLANs 1002 to 1005 are always pruning-ineligible; traffic from
these VLANs cannot be pruned. Extended-range VLANs (VLAN IDs higher than 1005) are also
pruning-ineligible.
Catalyst 2960-XR Switch VLAN Configuration Guide, Cisco IOS Release 15.0(2)EX1
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Configuring VTP
VTP Pruning