16-5
Cisco IE 3000 Switch Software Configuration Guide
OL-13018-03
Chapter 16 Configuring VTP
Understanding VTP
Figure 16-1
Flooding Traffic without VTP Pruning
Figure 16-2
shows a switched network with VTP pruning enabled. The broadcast traffic from Switch A
is not forwarded to Switches C, E, and F because traffic for the Red VLAN has been pruned on the links
shown (Port 5 on Switch B and Port 4 on Switch D).
Figure 16-2
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 trunk
only (not on all switches in the VTP domain).
See the
“Enabling VTP Pruning” section on page 16-14
. 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.
S
witch D
S
witch E
S
witch C
S
witch F
S
witch A
S
witch B
Port 1
Port 2
Red
VLAN
89240
S
witch D
S
witch E
S
witch C
S
witch F
S
witch A
S
witch B
Port 1
Port 2
Red
VLAN
89241
Port
4
Flooded tr
a
ffic
i
s
pruned.
Port
5
Flooded tr
a
ffic
i
s
pruned.