What is the VTP domain and how to configure the VTP domain on the Cisco Switch?
VTP domain is the domain name given to the switches while configuring the VTP on Cisco switches. For the proper trunk connection between two switches, the VTP domain should match otherwise trunk connection will fail and we will see the following error on the switch.
You can try giving a different domain name to any of the switches to see this warning message on the interface.
If we want any switch to accept and forward the VTP updates then we have to assign the same domain to that switch otherwise switch will not accept the updates.
To configure the VTP domain, we can use the following command.
VTP domain (domain name)
Switch(config)#vtp domain Lab
In this lab, we have created a VTP domain called Lab. We can test creating the VLANs on switches to check how the switches on the same domains are updating the VLAN information in their databases.
VTP transparent mode will ignore the VTP updates anyhow so we can ignore the domain configuration for the switch configured with the transparent mode.
We can see in the image below that 4 created VLANs are showing up in every switch which means that VLAN information was successfully replicated to all the switches except the transparent mode switch.
Changing VTP domain
To change the VTP domain, we can use the same command mentioned above and we can give any domain name however this should be changed on all the switches if VTP has been enabled.
You can download this lab and try creating the VLANs to see the VLAN information updating.
We have created a domain mismatch on the transparent mode switch so you have to fix the mismatch by removing the domain name.
VTP information is saved on the switch so you have to delete the Vlan.dat file to remove the VTP configuration.
After fixing the domain issues, you can create new VLANs on the server mode switch and the information should be replicated to all the switches.
