On Junos devices, the two types of tunnels that can be created universally are GRE (Generic Routing Encapsulation) and IP-IP (Internet Protocol-In-Internet Protocol). GRE is a widely supported tunneling protocol allowing the encapsulation of a wide variety of network layer protocols inside virtual point-to-point links. IP-IP is another tunneling method useful for encapsulating one IP packet within another IP packet. These two types of tunnels are supported across the various types of Junos devices, including routers and switches.