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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
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Chapter 16 Configuring VTP Configuring VTP
VTP Configuration Guidelines
You use the vtp global configuration command to set the VTP password, the version, the VTP file name,
the interface providing updated VTP information, the domain name, and the mode, and to disable or
enable pruning. For more information about available keywords, see the command descriptions in the
command reference for this release. The VTP information is saved in the VTP VLAN database. When
VTP mode is transparent, the VTP domain name and mode are also saved in the switch running
configuration file, and you can save it in the switch startup configuration file by entering the copy
running-config startup-config privileged EXEC command. You must use this command if you want to
save VTP mode as transparent, even if the switch resets.
When you save VTP information in the switch startup configuration file and reboot the switch, the switch
configuration is selected as follows:
• If the VTP mode is transparent in the startup configuration and the VLAN database and the VTP
domain name from the VLAN database matches that in the startup configuration file, the VLAN
database is ignored (cleared), and the VTP and VLAN configurations in the startup configuration
file are used. The VLAN database revision number remains unchanged in the VLAN database.
• If the VTP mode or domain name in the startup configuration do not match the VLAN database, the
domain name and VTP mode and configuration for the first 1005 VLANs use the VLAN database
information.

Domain Names

When configuring VTP for the first time, you must always assign a domain name. You must configure
all switches in the VTP domain with the same domain name. Switches in VTP transparent mode do not
exchange VTP messages with other switches, and you do not need to configure a VTP domain name
for them.
Note If NVRAM and DRAM storage is sufficient, all switches in a VTP domain should be in VTP server
mode.
Caution Do not configure a VTP domain if all switches are operating in VTP client mode. If you configure the
domain, it is impossible to make changes to the VLAN configuration of that domain. Make sure that you
configure at least one switch in the VTP domain for VTP server mode.

Passwords

You can configure a password for the VTP domain, but it is not required. If you do configure a domain
password, all domain switches must share the same password and you must configure the password on
each switch in the management domain. Switches without a password or with the wrong password reject
VTP advertisements.
If you configure a VTP password for a domain, a switch that is booted without a VTP configuration does
not accept VTP advertisements until you configure it with the correct password. After the configuration,
the switch accepts the next VTP advertisement that uses the same password and domain name in the
advertisement.
If you are adding a new switch to an existing network with VTP capability, the new switch learns the
domain name only after the applicable password has been configured on it.