draft-ietf-intarea-v4-via-v6
IPv4 routes with an IPv6 next hop
V4-via-v6 routing is a technique that uses IPv6 next-hop addresses
for routing IPv4 packets, and thus makes it possible to route IPv4
packets across a network where some routers have not been assigned
IPv4 addresses. This document describes v4-via-v6 routing, and
defines related operational procedures, notably the origination of
ICMPv4 packets by nodes that might not have an IPv4 address.