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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
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Chapter 16 Configuring VTP
Configuring VTP
Caution When you configure a VTP domain password, the management domain does not function properly if you
do not assign a management domain password to each switch in the domain.
VTP Version
Follow these guidelines when deciding which VTP version to implement:
• All switches in a VTP domain must have the same domain name, but they do not need to run the
same VTP version.
• A VTP version 2-capable switch can operate in the same VTP domain as a switch running VTP
version 1 if version 2 is disabled on the version 2-capable switch (version 2 is disabled by default).
• If a switch running VTP version 1 but capable of running VTP version 2 receives VTP version 3
advertisements, it automatically moves to VTP version 2.
• If a switch running VTP version 3 is connected to a switch running VTP version 1, the VTP version
1 switch moves to VTP version 2, and the VTP version 3 switch sends scaled-down versions of the
VTP packets so that the VTP version 2 switch can update its database.
• A switch running VTP version 3 cannot move to version 1 or 2 if it has extended VLANs.
• Do not enable VTP version 2 on a switch unless all of the switches in the same VTP domain are
version-2-capable. When you enable version 2 on a switch, all of the version-2-capable switches in
the domain enable version 2. If there is a version 1-only switch, it does not exchange VTP
information with switches that have version 2 enabled.
• Cisco recommends placing VTP version 1 and 2 switches at the edge of the network because they
do not forward VTP version 3 advertisements.
• If there are TrBRF and TrCRF Token Ring networks in your environment, you must enable VTP
version 2 or version 3 for Token Ring VLAN switching to function properly. To run Token Ring and
Token Ring-Net, disable VTP version 2.
• VTP version 1 and version 2 do not propagate configuration information for extended range VLANs
(VLANs 1006 to 4094). You must configure these VLANs manually on each device. VTP version 3
supports extended-range VLANs. You cannot convert from VTP version 3 to VTP version 2 if
extended VLANs are configured.
• When a VTP version 3 device trunk port receives messages from a VTP version 2 device, it sends a
scaled-down version of the VLAN database on that particular trunk in VTP version 2 format. A VTP
version 3 device does not send VTP version 2-formatted packets on a trunk unless it first receives
VTP version 2 packets on that trunk port.
• When a VTP version 3 device detects a VTP version 2 device on a trunk port, it continues to send
VTP version 3 packets, in addition to VTP version 2 packets, to allow both kinds of neighbors to
coexist on the same trunk.
• A VTP version 3 device does not accept configuration information from a VTP version 2 or version
1 device.
• Two VTP version 3 regions can only communicate in transparent mode over a VTP version 1 or
version 2 region.
• Devices that are only VTP version 1 capable cannot interoperate with VTP version 3 devices.