VTP Pruning
VTP pruning uses VLAN advertisements to determine when a trunk connection is ?¬‚ooding
traf?¬?c needlessly.
By default, a trunk connection carries traf?¬?c for all VLANs in the VTP management
domain. In many enterprise networks, not every switch will have ports assigned to every
VLAN.
Figure 2-13 shows a switched network with VTP pruning enabled. Only switches 2, 4, and
5 support ports con?¬?gured in VLAN 3. Switch 5 does not forward the broadcast traf?¬?c from
host X to switches 1 and 3 because traf?¬?c for VLAN 3 has been pruned on the links between
switch 5 and switch 1 and switch 3, as indicated in the ?¬?gure.
VTP pruning increases available bandwidth by restricting ?¬‚ooded traf?¬?c to those trunk
links that the traf?¬?c must use to access the appropriate network devices.
You can enable pruning only on Cisco Catalyst switches that are con?¬?gured for VTP
servers, and not on clients.
NOTE In the overwrite process, if the VTP server deleted all the VLANs and had the
higher revision number, the other devices in the VTP domain would also delete their
VLANs.
30 Chapter 2: Medium-Sized Switched Network Construction
Figure 2-13 VTP Pruning
Configuring VLANs and Trunks
By default, all the ports on a Catalyst switch are in VLAN 1.
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