Complete these steps in order to split an existing VTP domain into two seperate VTP domains:
Note: During the procedure, you can use any temporary domain name, for example, temp_domain.
On the device that is suppose to be the VLAN Trunking Protocol (VTP) server for domain1, issue the vtp mode transparent command in order to change VTP mode to transparent.
Change the domain name to temp_domain. This clears the revision number.
Change the domain name to domain1, then issue the vtp mode server command in order to change the VTP mode to server.
Repeat the previous procedure for the rest of the switches, but make sure the VTP mode is set as client.
Now, repeat the same procedure for domain2 and begin with the device that is supposed to be the VTP Server. Then continue with the clients.
Refer to All Transparent VTP Domain to Server-Client VTP Domain Migration Configuration Example for more information.