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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-25303-03
Chapter 1 Configuring VTP
Understanding VTP
When you make a change to the VLAN configuration on a VTP server, the change is propagated to all
switches in the VTP domain. VTP advertisements are sent over all IEEE trunk connections, including
Inter-Switch Link (ISL) and IEEE 802.1Q. VTP dynamically maps VLANs with unique names and
internal index associates across multiple LAN types. Mapping eliminates excessive device
administration required from network administrators.
If you configure a switch for VTP transparent mode, you can create and modify VLANs, but the changes
are not sent to other switches in the domain, and they affect only the individual switch. However,
configuration changes made when the switch is in this mode are saved in the switch running
configuration and can be saved to the switch startup configuration file.
For domain name and password configuration guidelines, see the “Domain Names” section on page 1-9.
VTP Modes
You can configure a supported switch or switch stack to be in one of the VTP modes listed in Table 1-1.
Table 1-1 VTP Modes
VTP Mode Description
VTP server In VTP server mode, you can create, modify, and delete VLANs, and specify other configuration
parameters (such as the VTP version) for the entire VTP domain. VTP servers advertise their VLAN
configurations to other switches in the same VTP domain and synchronize their VLAN configurations with
other switches based on advertisements received over trunk links.
VTP server is the default mode.
In VTP server mode, VLAN configurations are saved in NVRAM. If the switch detects a failure while
writing a configuration to NVRAM, VTP mode automatically changes from server mode to client mode. If
this happens, the switch cannot be returned to VTP server mode until the NVRAM is functioning.
VTP client A VTP client behaves like a VTP server and transmits and receives VTP updates on its trunks, but you
cannot create, change, or delete VLANs on a VTP client. VLANs are configured on another switch in the
domain that is in server mode.
In VTP versions 1 and 2, in VTP client mode, VLAN configurations are not saved in NVRAM. In VTP
version 3, VLAN configurations are saved in NVRAM in client mode.
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