RFC 6052, "IPv6 Addressing of IPv4/IPv6 Translators", October 2010Source of RFC: behave (tsv)
Errata ID: 5547
Publication Format(s) : TEXT
Reported By: Fred Baker
Date Reported: 2018-11-06
Rejected by: Mirja Kühlewind
Date Rejected: 2018-11-26
Section 3.1 says:
The Well-Known Prefix MUST NOT be used to represent non-global IPv4 addresses, such as those defined in [RFC1918] or listed in Section 3 of [RFC5735]. Address translators MUST NOT translate packets in which an address is composed of the Well-Known Prefix and a non- global IPv4 address; they MUST drop these packets.
It should say:
The paragraph should be removed.
IPv4 packets with private addresses are routinely translated to IPv4 packets with global addresses in NAT44. If a 464XLAT CLAT (stateless NAT64) cannot translate a private address to an IPv6 /96 prefix with that address as an IID (or whatever it's called), then the packet may not be translated to an IPv4 packet with a global address by the 464XLAT PLAT (stateful NAT64). This changes the intent of the sender, and in so doing violates the end to end principle. Practically speaking, it means that a network that uses 464XLAT or MAP-T with IPv4 in the subscriber and translating to IPv4 via NAT64 into the IPv4 Internet, it forces the network or the subscriber to purchase global address space. That's just silly. Let the user use private address space in the home or whatever.
The orginial text was intended at time of publication. If this is not current anymore, the RFC needs to be updated by an IETF consensus doc.