Cisco 4500M Software Manual page 358

Overview of VTP
For VTP pruning to be effective, all devices in the management domain must either support VTP pruning
or, on devices that do not support VTP pruning, you must manually configure the VLANs allowed on
trunks.
Figure 27-1
Interface 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 interfaces in the Red VLAN.
You can enable pruning globally on the Catalyst 4500 series switch (see the
section on page
Figure 27-1 Flooding Traffic without VTP Pruning
Catalyst series
Catalyst series
switch 6
Figure 27-2
Switch 1 is not forwarded to Switches 3, 5, and 6 because traffic for the Red VLAN has been pruned on
the links indicated (Interface 5 on Switch 2 and Interface 4 on Switch 4).
Figure 27-2 Flooding Traffic with VTP Pruning
Flooded traffic
is pruned.
Switch 5
Switch 6
Software Configuration Guide—Release 12.2(25)EW
27-4
shows a switched network without VTP pruning enabled. Interface 1 on Switch 1 and
27-6).
Catalyst series
switch 4
Catalyst series
switch 5
switch 2
Catalyst series Catalyst series
switch 3
shows the same switched network with VTP pruning enabled. The broadcast traffic from
Switch 4
Interface 2
Interface 4
Switch 2
Interface 5
Switch 3 Switch 1
Interface 2
Interface 1
switch 1
Red
VLAN
Interface 1
Chapter 27 Understanding and Configuring VTP
"Enabling VTP Pruning"
Red
VLAN
OL-6696-01