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Catalyst2950 and Catalyst2955 Switch Software Configuration Guide
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Chapter18 Configuring VTP
Configuring VTP
VTP Configuration Guidelines
These sections describe guidelines you should follow when implementing VTP in your network.

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 configur ation,
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 functi on properly if you
do not assign a management domain password to each switch in the domain.

Upgrading from Previous Software Releases

When you upgrade from an IOS software version that supports VLANs but does not su pport VTP, such
as Release 12.0(5.1)WC, to a version that does support VTP, ports that belong to a VLAN retain their
VLAN membership, and VTP enters transparent mode. The domain name becomes UPGRADE, and
VTP does not propagate the VLAN configuration to other switches.
If you want the switch to propagate VLAN configuration information to other switc hes and to learn the
VLANs enabled on the network, you must configure the switch w it h th e corr ec t d oma in na me a nd
domain password and change the VTP mode to VTP server.