et

In computer networks, a tunneling protocol allows a network user to access or provide a network service that the underlying network does not support or provide directly. One important use of a tunneling protocol is to allow a foreign protocol to run over a network that does not support that particular protocol; for example, running IPv6 over IPv4.

The Neighbor Discovery Protocol (NDP, ND)^[1] is a protocol in the Internet protocol suite used with Internet Protocol Version 6 (IPv6).