Tunnel Interface

A tunnel interface is a virtual logical interface. To apply certain types of tunnels, you must create a tunnel interface first.

The destination address specified on the local tunnel interface is the IP address of the peer interface that receives packets. This address must be the same as the source address specified on the peer tunnel interface. In addition, routes to the peer interface that receives packets must be reachable. The same source or destination address cannot be configured for two or more tunnel interfaces that use the same encapsulation protocol.

Different encapsulation modes can be configured for tunnel interfaces depending on the utilities of the interfaces. The following table lists the types of tunnels for which tunnel interfaces can be created.

**Table 1** Tunnel types supported by tunnel interfaces
Tunnel Type	Encapsulation Protocol	Usage Scenario
IPv6 over IPv4 tunnel	IPv4	An IPv6 over IPv4 manual tunnel is manually configured between the two border devices. The source and destination IPv4 addresses of the tunnel need to be statically specified. IPv6 over IPv4 manual tunnels can be used for communications between isolated IPv6 sites, or configured between a border device and a host. An IPv6 over IPv4 manual tunnel offers the point-to-point service.
6to4 tunnel	IPv4	A 6to4 tunnel can connect multiple IPv6 isolated sites through an IPv4 network. Compared with an IPv6 over IPv4 manual tunnel, a 6to4 tunnel can be a point-to-multipoint connection, whereas an IPv6 over IPv4 manual tunnel is a P2P connection. Devices on both ends of a 6to4 tunnel are not configured in pairs.
MPLS TE tunnel	An MPLS TE tunnel is established through the cooperation of a series of protocol components. For details, see "MPLS TE Fundamentals" > Technical Overview in the product manual.	An MPLS TE tunnel is uniquely identified by the following parameters: Tunnel interface: The interface type is "tunnel." The interface number is expressed in the format of SlotID/CardID/PortID. Tunnel ID: a decimal number that identifies an MPLS TE tunnel and facilitates tunnel planning and management. A tunnel ID must be specified before an MPLS TE tunnel interface is configured.
GRE tunnel	GRE	GRE provides a mechanism of encapsulating packets of a protocol into packets of another protocol. This allows packets to be transmitted over heterogeneous networks. The channel for transmitting heterogeneous packets is called a tunnel.
IPsec tunnel	IPSec	A security policy group is applied to tunnel interfaces to protect different data flows. Only one security policy group can be applied to a tunnel interface.
IPv4 over IPv6 tunnel	IPv6	An IPv4 over IPv6 manual tunnel is a tunnel manually configured between two border routers. The source and destination IPv6 addresses of the tunnel need to be statically specified. A manual tunnel is used for communication between IPv4 networks and can also be configured between a border router and host. An IPv4 over IPv6 manual tunnel works in P2P mode.
6RD tunnel	IPv4	A 6RD tunnel is a point-to-multipoint tunnel that connects to IPv6 sites through a carrier's IPv4 network. A tunnel interface must be created before the tunnel encapsulation type is set to 6RD.