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Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
OL-10101-02
Chapter 17 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 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.
Upgrading from Previous Software Releases
When you upgrade from an IOS software version that supports VLANs but does not support 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 switches and to learn the
VLANs enabled on the network, you must configure the switch with the correct domain name and
domain password and change the VTP mode to VTP server.