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Catalyst 2900 Series XL and Catalyst 3500 Series XL Software Configuration Guide
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Chapter 8 Configuring VLANs
Using VTP
VTP Configuration Guidelines
Domain Names
When configuring VTP for the first time, you must always assign a domain name. All switches in the
VTP domain must also be configured 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.
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. Therefore, make
sure you configure at least one switch in the VTP domain for VTP server mode.
VTP Version Numbers
When you add a VTP client, follow this caution and procedure:
Caution Before adding a VTP client to a VTP domain, always verify that its VTP configuration revision number
is lower than the configuration revision number of the other switches in the VTP domain. If necessary,
reset the switch configuration revision number to 0. Switches in a VTP domain always use the VLAN
configuration of the switch with the highest VTP configuration revision number. If you add a switch that
has a revision number higher than the revision number in the VTP domain, it can erase all VLAN
information from the VTP server and VTP domain.
Beginning in user EXEC mode, follow these steps to verify and reset the VTP configuration revision
number on a switch before adding it to a VTP domain:
Command Purpose
Step 1
show vtp status Check the VTP configuration revision number.
If the number is 0, add the switch to the VTP domain.
If the number is greater than 0, follow these steps:
a. Write down the domain name.
b. Write down the configuration revision number.
Continue with the next steps to reset the configuration revision number on the
switch.
Step 2
enable Enter privileged EXEC mode.
Step 3
vlan database Enter VLAN database mode.
Step 4
vtp domain domain-name Change the domain name from the original one displayed in Step 1 to a new name.
Step 5
exit The VLAN information on the switch is updated, and the configuration revision
number is reset to 0. You return to privileged EXEC mode.
Step 6
show vtp status Verify that the configuration revision number has been reset to 0.
Step 7
vlan database Enter VLAN database mode.
Step 8
vtp domain domain-name Enter the original domain name on the switch.
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