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Catalyst 3750 Switch Software Configuration Guide
OL-8550-09
Chapter 14 Configuring VTP
Configuring VTP
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 if the switch resets.
When you save VTP information in the switch startup configuration file and restart the switch, the
configuration is selected as follows:
• If the VTP mode is transparent in both 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). 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 the domain name in the startup configuration do not match the VLAN database,
the domain name and the 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.
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.