Tunneling protocol

A tunneling protocol is a network protocol which encapsulates one protocol or session inside another. Protocol A is encapsulated within protocol B, such that A treats B as though it were a data link layer. Tunneling is used to get data between administrative domains which use a protocol that is not supported by the internet connecting those domains.

Examples include:

Datagram-based:

• L2TP (Layer 2 Tunneling Protocol)
• MPLS (Multi-Protocol Label Switching)
• GRE (Generic Routing Encapsulation)
• PPTP (Point-to-Point Tunneling Protocol)
• PPPoE (point-to-point protocol over Ethernet)
• PPPoA (point-to-point protocol over ATM )
• IP in IP Tunneling (RFC 1853)
• IPsec
• IEEE 802.1Q (Ethernet VLANs)
• DLSw (SNA over IP)
• XOT (X.25 datagrams over a [[Transmission Control Protocol|TCP]

Stream-based:

• TLS
• SSH

References