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| 2.7 |  | VLAN Trunking Protocol (VTP) |
| 2.7.4 |  | Adding a switch to a VTP domain |

Use caution when inserting a new switch into an existing domain. In order to prepare a switch to enter an existing VTP domain, perform the following steps.

Delete the VLAN database, erase the startup configuration, and power cycle the switch. This will avoid potential problems resulting from residual VLAN configurations or adding a switch with a higher VTP configuration revision number that could result in the propagation of incorrect VLAN information. From the privileged mode, issue the delete vlan.dat and erase startup-config commands, then power cycle the switch.

Determine the VTP mode of operation of the switch and include the mode when setting the VTP domain name information on the switch. If you leave the switch in server mode, be sure to verify that the configuration revision number is set to 0 before adding the switch to the VTP domain. It is generally recommended that you have several servers in the domain, with all other switches set to client mode for purposes of controlling VTP information.

It is also highly recommended that you use secure mode in your VTP domain. Assigning a password to the domain will accomplish this. This will prevent unauthorized switches from participating in the VTP domain. From the privileged mode or VLAN configuration mode, use the vtp password password command.