Tunneling: A general term for getting things through rather than over a barrier -- figurative or literal. In computer networking parlance, tunneling generally refers to wrapping message packets for a protocol which is not routed by the network within packets of a protocol that is routed. Thus, for example, Microsoft can tunnel their NETBEUI protocol within IPX or TCP/IP packets for transmission over networks that will not route NETBEUI's native NETBIOS protocol.

The Point to Point Tunneling Protocol (PPTP) can be used to create Virtual Private Networks -- networks that appear to the participants to be small and private using public networks to provide much or all of the infrastructure. PPTP can be used to tunnel IPX (Novell), NETBEUI (Microsoft) or IP packets over IP networks. Tunneling of IP within IP packets is often required when a local network uses IP addresses internally that might not be compatible with external IP numbers.

Return To Index Copyright 1994-2002 by Donald Kenney.