Select from “Tunnel” and “Transport”.
Tunnel: Commonly used between gateways, or at an end-station to a
gateway, the gateway acting as a proxy for the hosts behind it.
Transport: Used between end-stations or between an end-station and a
gateway, if the gateway is being treated as a host—for example, an
encrypted Telnet session from a workstation to a router, in which the
router is the actual destination.