Cisco WS-C3550-12G Software Configuration Manual page 243

Chapter 9 Creating and Maintaining VLANs
Figure 9-2
Switch 6
Figure 9-3
not forwarded to Switches 3, 5, and 6 because traffic for the Red VLAN has been pruned on the links
shown (Port 5 on Switch 2 and Port 4 on Switch 4).
Figure 9-3
Flooded traffic
is pruned.
Switch 5
Switch 6
Enabling VTP pruning on a VTP server enables pruning for the entire management domain. See the
"Enabling VTP Pruning" section on page
enable it. VTP pruning does not prune traffic from VLANs that are pruning-ineligible. VLAN 1 is always
pruning-ineligible; traffic from VLAN 1 cannot be pruned.
VTP pruning is not designed to function in VTP transparent mode. If one or more switches in the
network are in VTP transparent mode, you should do one of these:
Turn off VTP pruning in the entire network.
•
• Turn off VTP pruning by making all VLANs on the trunk of the switch upstream to the VTP
transparent switch pruning ineligible.
78-11194-03
Flooding Traffic without VTP Pruning
Switch 4
Switch 5
Switch 2
Switch 3
shows a switched network with VTP pruning enabled. The broadcast traffic from Switch 1 is
Optimized Flooded Traffic with VTP Pruning
Switch 4
Port 2
Port
4
Flooded traffic
Port
is pruned.
5
Switch 3
Port 2
Red
VLAN
Port 1
Switch 1
Switch 2
Red
VLAN
Port 1
Switch 1
9-13. VTP pruning takes effect several seconds after you
Catalyst 3550 Multilayer Switch Software Configuration Guide
Using the VLAN Trunking Protocol
9-7