Let’s discuss why VTP is not recommended and how to disable VTP on the Cisco switch
VTP replicates the VLANs created on one switch to other switches in the network so it appears to be a useful feature however, this feature does not fulfill any requirement. Moreover, VTP can cause a network outage.
We should not use VTP in our network for the following reasons.
Cisco proprietary
VTP is Cisco’s proprietary protocol so it only works with the Cisco switches. If we want to use VTP in our network then we have to use only Cisco switches for our topologies.
Proper configuration
Configuring VTP all over the network can be a demanding task because we have to assign VTP modes correctly to each switch as per our requirements and we also have to define the domain name and password for each switch. In case we want to use more than 1 VTP domain in the network then it makes configuring even harder.
VTP can cause issues with the network
VTP uses the revision number to send the VTP updates so whichever switch has the bigger number, its VLAN database will be replicated to other switches in the network. This working mechanism may lead to network downtime if anybody connected the other switch in the existing network that has a bigger revision number. When VTP will realize that the newly connected switch has the bigger revision number then it will wipe out the entire VLAN configuration of other switches and will replace it with the VLANs created on the new switch.
Although VTP updates will only be accepted by the other switches if the VTP domain name and password are same on the other switches. Sometimes, this can be possible when the staging network switch is used in the production network. Many times switches on the staging network are configured to mimic the production network so upon the requirement of more connections in the network, someone decides to use the old switch from the lab having the higher revision number then it will immediately cause the network outage as its VLANs will be replicated to other switches and all the ports assigned to VLANs will be unassigned if any particular VLAN will not exist.
VTP is not useful
VTP only replicates the VLANs created on the switch however we still have to assign ports to those VLANs. Creating a VLAN only takes one command so using the VTP just to create VLANs on other switches does not make our work easier in any way as we have to configure everything else on our own.
VTP pruning issue
VTP pruning helps to reduce the unnecessary traffic in the network however it only works when all the switches are configured with the VTP server mode. This again increases the risk of jeopardizing the network as the VTP server has the ability to update the VLAN database and send the VTP updates so every switch in the network can update the VLAN database and in case someone messed up the VLAN configuration on any switch then it will jeopardize the whole network.
Conclusion
As discussed, VTP can cause more harm to the production network than doing any good hence it is the best practice to not use VTP in our network. To disable the VTP we can use the following command.
Switch(config)#vtp mode transparent
Setting device to VTP TRANSPARENT mode.
Setting up VTP transparent mode on the switches will disable the VTP on the switch however switch can still pass the VTP updates to other switches to best practice is to enable transparent mode on all switches used in the network.
