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
switch running VTP version 1 if version 2 is
disabled on the version 2-capable
switch (version 2 is disabled by default).
switch running VTP version 1, but capable of
running VTP version 2, receives VTP version 3 advertisements, it automatically
moves to VTP version 2.
switch running VTP version 3 is connected to
switch running VTP version 1, the VTP version
switch moves to VTP version 2, and the VTP
switch sends scaled-down versions of the VTP
packets so that the VTP version 2
switch can update its database.
switch running VTP version 3 cannot move to
version 1 or 2 if it has extended VLANs.
Do not enable VTP version 2
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
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 and support for extended range VLAN database propagation.
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
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.
VTP version 1 and version 2, if extended-range VLANs are configured on the
switch stack, you cannot change VTP mode to
client or server. You receive an error message, and the configuration is not
allowed. VTP version 1 and version 2 do not propagate configuration
information for extended range VLANs (VLANs 1006 to 4094). You must manually
configure these VLANs on each device.
For VTP version 1 and 2,
before you create extended-range VLANs (VLAN IDs 1006 to 4094), you must set
VTP mode to transparent by using the
vtp mode transparent
global configuration command. Save this
configuration to the startup configuration so that the
switch starts in VTP transparent mode.
Otherwise, you lose the extended-range VLAN configuration if the
switch resets and boots up in VTP server mode
version 3 supports extended-range VLANs. If extended VLANs are configured, you
cannot convert from VTP version 3 to VTP version 2.
If you configure the
switch for VTP client mode, the
switch does not create the VLAN database file
(vlan.dat). If the
switch is then powered off, it resets the VTP
configuration to the default. To keep the VTP configuration with VTP client
mode after the
switch restarts, you must first configure the
VTP domain name before the VTP mode.
switches are operating in VTP client mode, do
not configure a VTP domain name. If you do, it is impossible to make changes to
the VLAN configuration of that domain. Therefore, make sure you configure at
switch as a VTP server.