Beforeadding a VTP client switch to a VTP domain, always verify that its VTP configuration revision
numberis lower than the configuration revision number of the other switches in the VTP domain. Switches
ina VTPdomain always use the VLAN configuration of the switch with the highest VTP configuration
revisionnumber. If you add a switch that has a revision number higher than the revision number in the
VTPdomain, it can erase all VLAN information from the VTP server and VTP domain.
Note
Whenyou make a change to the VLAN configuration on a VTP server, the change is propagated to all switches
inthe VTPdomain. VTP advertisements are sent over all IEEE trunk connections, including IEEE 802.1Q.
VTPdynamically maps VLANs with unique names and internal index associates across multiple LAN types.
Mappingeliminates excessive deviceadministration required from networkadministrators.
Ifyou configure a switch for VTP transparent mode, you can create and modify VLANs, but the changes are
notsent to other switches in the domain, and they affect only the individual switch. However, configuration
changesmade when the switch is in this mode are saved in the switch running configuration and can be saved
tothe switchstartup configuration file.
Related Topics
Addinga VTP Client Switch to a VTP Domain, on page 32
VTP Modes
Table 4: VTP Modes
DescriptionVTP Mode
InVTP server mode, you can create, modify, and delete VLANs, and specify other
configurationparameters (such as the VTP version) for the entire VTP domain. VTP servers
advertisetheir VLAN configurations to other switches in the same VTP domain and
synchronizetheir VLAN configurations with other switches based on advertisements received
overtrunk links.
VTPserver isthe default mode.
InVTP servermode, VLAN configurations are saved in NVRAM. If the switch detects a
failurewhile writinga configurationto NVRAM, VTPmode automaticallychanges from
servermode to client mode. If this happens, the switch cannot be returned to VTP server
modeuntil the NVRAM is functioning.
VTPserver
AVTP client functions like a VTP server and transmits and receives VTP updates on its
trunks,but you cannotcreate, change, or delete VLANs on a VTP client. VLANs are
configuredon another switch in thedomain that is inserver mode.
InVTP versions 1 and 2 in VTP client mode, VLAN configurations are not saved in NVRAM.
InVTP version 3, VLAN configurations are saved in NVRAM in client mode.
VTPclient
Catalyst 2960-XR Switch VLAN Configuration Guide, Cisco IOS Release 15.0(2)EX1
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Configuring VTP
VTP Modes