Basics: Cisco VLAN Trunking Protocol – Transparent discard and passing VTP Packets

It’s a common discussion about when Cisco VTP protocol is actually forwarded through Cisco switches and when it’s isn’t. I’ve always gotten it somewhat confused and when I stumbled across some old notes on the topic I had an ah-hah moment. I’m answering the equation about when using VTP in your network, which versions are risky – that’s risky is terms of how do you prevent VTP updates from ‘crossing’ a switch.