Core issue
A misconfiguration on a switch can cause the configuration updates of the VLAN Trunk Protocol (VTP) to fail.
A common problem in most cases is that the new VLAN created in the VTP server switch does not propogate to the VTP client switches, which creates host connectivity issues.
In some cases, you can find that the VTP Client does have the latest VLAN updates even though it can talk to all the devices on the network due to VTP convergence issues.
Resolution
A switch that is not configured correctly for VTP does not update its VLAN configuration. Verify these configuration settings:
Verify that the switches are connected through trunk links, because VTP updates are only exchanged over trunk links. Issue the show trunk command.
Verify that the VTP domain name is exactly the same on the appropriate switches. The name is case sensitive. The VTP updates are only exchanged between switches in the same VTP domain. Issue the show vtp domain command in order to verify the domain name. Issue the set vtp domain domain_name command in order to set the VTP domain name.
Verify that the VTP mode on the switch. Switches in transparent mode do not update their VLAN configuration based on VTP updates from other switches. Switches in server mode or client mode do. Issue the show vtp domain command in order to verify the mode. Issue the set vtp mode {client | server | transparent | off} command in order to set the VTP mode.
Verify that the VTP password is exactly the same on all the switches in the domain. The password is case sensitive. If a password is configured, it must be configured on all switches in the domain and the password must be the same. In order to clear a VTP password, issue the set vtp passwd 0 command.
Refer to Understanding and Configuring VLAN Trunk Protocol (VTP) for more VTP information, as well as Integrated Cisco IOS commands for VTP.
VTP version 1 and VTP version 2 are not interoperable on the network devices in the same VTP domain. A VTP version 2 capable network device can operate with a network device that runs VTP version 1, provided that VTP version 2 is disabled on the VTP version 2 capable network device. VTP version 2 is disabled by default. Every network device in the VTP domain must use the same VTP version.
Sometimes the VLAN 1003 parent VLAN missing error messages are received while attempts are made to add VLANs. This occurs mainly when there is a VTP version mismatch between the switches in a VTP domain. Issue the show vtp status command in order to verify the VTP version that runs on a switch. If VTP version 2 is enabled, disable it in order to resolve this issue.
In case of VTP convergence issue, where a VTP client does not update the VLAN information, the workaround is to force a VTP convergence by the creation, then the removal of a dummy VLAN on the VTP server. This increments the revision number and forces all VTP clients to update their VLAN database.
Refer to the VTP Configuration Guidelines and Restrictions section of Configuring VLAN Trunking Protocol (VTP) for more information.
