VTPpruning still applies only to VLANs 1 to 1005, and VLANs 1002 to 1005 are still
reservedand cannot be modified.
Note
•PrivateVLAN support.
•Supportfor any database in a domain—In addition to propagatingVTP information, version 3can
propagateMultiple Spanning Tree (MST) protocol database information. A separate instance of the VTP
protocolruns foreach applicationthat uses VTP.
•VTPprimary server and VTP secondary servers—A VTP primary server updates the database information
andsends updates that are honored by all devices in the system. A VTP secondary server can only back
upthe updatedVTP configurations received from the primary server to its NVRAM.
Bydefault, all devices come up as secondary servers. You can enter the vtp primary privileged EXEC
commandto specify a primary server. Primary server status is only needed for database updates when
theadministrator issues a takeover message in the domain. You can have a working VTP domain without
anyprimary servers.Primary server statusis lost ifthe devicereloads or domainparameters change,
evenwhen a passwordis configuredon the switch.
•Theoption to turn VTP on or off on a per-trunk (per-port) basis—You can enable or disable VTP per
portby enteringthe [no]vtp interface configuration command. When you disable VTP on trunking
ports,all VTP instances for that port are disabled. You cannot set VTP to off for the MST database and
onfor theVLAN databaseon the same port.
Whenyou globally set VTP mode to off, it applies to all the trunking ports in the system. However, you
canspecify on or off on a per-VTP instance basis. For example, you can configure the switch as a VTP
serverfor theVLAN databasebut with VTP offfor theMST database.
VTP Pruning
VTPpruning increases network available bandwidth by restricting flooded traffic to those trunk links that the
trafficmust use to reach the destination devices. Without VTP pruning, a switch floods broadcast, multicast,
andunknown unicast traffic across all trunk links within a VTP domain even though receiving switches might
discardthem. VTP pruningis disabledby default.
VTPpruning blocks unneeded flooded traffic to VLANs on trunk ports that are included in the pruning-eligible
list.Only VLANs included in the pruning-eligible list can be pruned. By default, VLANs 2 through 1001 are
pruningeligible switch trunk ports. If the VLANs are configured as pruning-ineligible, the flooding continues.
VTPpruning is supported in all VTP versions.
Catalyst 2960-XR Switch VLAN Configuration Guide, Cisco IOS Release 15.0(2)EX1
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Configuring VTP
VTP Pruning