What is VLAN Hopping I am starting on my journey into the world of Networking and have come across a term called VLAN hopping. The sentence I read was that if the Native VLAN on two switches connected to each other via their trunk interfaces had different Native VLANs, then VLAN Hopping could occur. Can someone please explain how exactly that occurs in a real world example? My apologies if the question is too broad, let me know and i will rephrase if possible.

VLAN hopping is when a client (unauthorized node) can add VLAN tags to its frames to enter VLANs that it's not supposed to be in or when it can generate MVRP/GVRP frames to make its port a member of additional VLANs. Either the switch adds the port to the unsecured VLAN automatically or its already been a member and the tagged frames were ignored before.

You should never activate dynamic VLAN protocols on edge ports and you should always control strict VLAN membership on all access ports or other ports that users have access to.

When trunk ports associate different native VLANs on either end, you connect those VLANs with each other. Sometimes you can use that to translate VLAN IDs but usually it's rather by mistake. Sometimes this is called _VLAN hopping_ as well. It's a good idea to tag all frames on a trunk and not use a native VLAN.