Cisco WS-SUP32-GE-3B - Supervisor Engine 32 Software Configuration Manual page 162

Understanding How VTP Works
For VTP pruning to be effective, all devices in the management domain must support VTP pruning. On
devices that do not support VTP pruning, you must manually configure the VLANs allowed on trunks.
Figure 11-1
and port 2 on Switch 4 are assigned to the Red VLAN. A broadcast is sent from the host connected to
Switch 1. Switch 1 floods the broadcast, and every network device in the network receives it, even
though Switches 3, 5, and 6 have no ports in the Red VLAN.
You enable pruning globally on the Catalyst 6500 series switch (see the
on page
Switching Port as a Trunk" section on page
Figure 11-1
Catalyst series
Switch 6
Figure 11-2
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).
Figure 11-2
Flooded traffic
is pruned.
Switch 5
Switch 6
Catalyst Supervisor Engine 32 PISA Cisco IOS Software Configuration Guide, Release 12.2ZY
11-4
shows a switched network without VTP pruning enabled. Interface 1 on network Switch 1
11-7). You configure pruning on Layer 2 trunking LAN ports (see the
Flooding Traffic without VTP Pruning
Catalyst series
Switch 4
Catalyst series
Catalyst series
Switch 5
Catalyst series
Switch 3
shows the same switched network with VTP pruning enabled. The broadcast traffic from
Flooding Traffic with VTP Pruning
Switch 4
Interface 2
Interface 4
Switch 2
Interface 5
Switch 3 Switch 1
8-8).
Interface 2
Switch 2
Red
VLAN
Interface 1
Catalyst series
Switch 1
Red
VLAN
Interface 1
Chapter 11 Configuring VTP
"Enabling VTP Pruning" section
"Configuring a Layer 2
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