Create a GRE tunnel to encapsulate a payload protocol
and connect two endpoints in a point-to-point, logical link.
Generic Routing Encapsulation (GRE) tunnel
protocol is a carrier protocol that encapsulates a payload protocol. The
GRE packet itself is encapsulated in a transport protocol (IPv4
or IPv6). The GRE tunnel connects two endpoints in a point-to-point,
logical link between the firewall and a router (or another firewall).
Palo Alto Networks firewalls support termination of a GRE tunnel.