How does a GRE tunnel work?
GRE works by encapsulating a payload — that is, an inner packet that needs to be delivered to a destination network — inside an outer IP packet. GRE tunnel endpoints send payloads through GRE tunnels by routing encapsulated packets through intervening IP networks. … GRE tunnels connect discontinuous sub-networks.
What is Generic Routing Encapsulation (GRE)? – Definition from …
Aug 1, 2019