Cisco Catalyst 3550 Series - Page 305

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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter 13 Configuring VTP
Understanding VTP
Figure 13-1 Flooding Traffic without VTP Pruning
Figure 13-2 shows a switched network with VTP pruning enabled. The broadcast traffic from Switch 1
is 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 13-2 Optimized Flooded Traffic with 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 device
only (not on all switches in the VTP domain). See the “Enabling VTP Pruning” section on page 13-13.
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.
Switch 4
Switch 5
Switch 3Switch 6 Switch 1
Switch 2
Port 1
Port 2
Red
VLAN
45826
Switch 4
Switch 5
Switch 3Switch 6 Switch 1
Switch 2
Port 1
Port 2
Red
VLAN
45827
Port
4
Port
5
Flooded traffic
is pruned.
Flooded traffic
is pruned.