3.2. IPv4 Addresses and IPv4-Mapped Addresses

The destination address selection algorithm operates on both IPv6 and IPv4 addresses. For this purpose, IPv4 addresses MUST be represented as IPv4-mapped addresses [RFC4291]. For example, to look up the precedence or other attributes of an IPv4 address in the policy table, look up the corresponding IPv4-mapped IPv6 address.

IPv4 addresses are assigned scopes as follows. IPv4 auto-configuration addresses [RFC3927], which have the prefix 169.254/16, are assigned link-local scope. IPv4 loopback addresses (Section 4.2.2.11 of [RFC1812]), which have the prefix 127/8, are assigned link-local scope (analogously to the treatment of the IPv6 loopback address (Section 4 of [RFC4007])). Other IPv4 addresses (including IPv4 private addresses [RFC1918] and Shared Address Space addresses [RFC6598]) are assigned global scope.

IPv4 addresses MUST be treated as having "preferred" (in the RFC 4862 sense) configuration status.