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Catalyst 3750 SwitchSoftware Configuration Guide
OL-8550-09
Chapter14 Configuring VTP
Configuring VTP
If you are configuring VTP on a cluster member switch to a VLAN, use the rcommand privileged EXEC
command to log in to the member switch. For more information about the command, see the command
reference for this release.
In VTP versions 1 and 2, when you configure extended-range VLANs on the switch, the switch must be
in VTP transparent mode. VTP version 3 also supports creating extended-range VLANs in client or
server mode.
VTP versions 1 and 2 do not support private VLANs. If you configure private VLANs, the switch must
be in VTP transparent mode. When private VLANs are configured on the switch, do not change the VTP
mode from transparent to client or server mode. VTP version 3 does support private VLANs.
Configuring VTP Mode
You can configure VTP mode as one of these:
•When a switch is in VTP server mode, you can change the VLAN configuration and have it
propagated throughout the network.
•When a switch is in VTP client mode, you cannot change its VLAN configuration. The client switch
receives VTP updates from a VTP server in the VTP domain and then modifies its configuration
accordingly.
•When you configure the switch for VTP transparent mode, VTP is disabled on the switch. The
switch does not send VTP updates and does not act on VTP updates received from other switches.
However, a VTP transparent switch running VTP version 2 does forward received VTP
advertisements on its trunk links.
•VTP off mode is the same as VTP transparent mode except that VTP advertisements are not
forwarded.
Follow these guidelines:
•For 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.
Note 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 (the default).
•VTP version 3 supports extended-range VLANs. If extended VLANs are configured, you cannot
convert from VTP version 3 to VTP version2.
•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.
Caution If all 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 least one switch as a VTP server.