RFC 6052, "IPv6 Addressing of IPv4/IPv6 Translators", October 2010Source of RFC: behave (tsv)
Errata ID: 5415
Publication Format(s) : TEXT
Reported By: Dale R. Worley
Date Reported: 2018-07-01
Rejected by: Magnus Westerlund
Date Rejected: 2020-01-16
Section 2.2 says:
Bits 64 to 71 of the address are reserved for compatibility with the host identifier format defined in the IPv6 addressing architecture [RFC4291]. These bits MUST be set to zero. When using a /96 Network-Specific Prefix, the administrators MUST ensure that the bits 64 to 71 are set to zero. A simple way to achieve that is to construct the /96 Network-Specific Prefix by picking a /64 prefix, and then adding 4 octets set to zero. [and other parts of the text]
It should say:
[This paragraph should be removed and corresponding changes made to the rest of section 2.2.]
Section 2.2 says that bits 64 to 71 of the Ipv6 address MUST be set to zero and references RFC 4291 as the authority. However, RFC 7136 says:
In particular, RFC 4291 defines a method by which the
Universal and Group bits of an IEEE link-layer address are mapped
into an IPv6 unicast interface identifier. This document clarifies
that those two bits are significant only in the process of deriving
interface identifiers from an IEEE link-layer address, and it updates
RFC 4291 accordingly.
Thus, the text I've referenced in RFC 6052 is to enforce a requirement that was not correctly applied, and RFC 6052's statement about bits 64 to 71 should be removed. In addition, there are consequent changes in other parts of RFC 6052, including Figure 1, where the "u" field should be removed from the address formats.
AD (Magnus Westerlund): A clarification by a later RFC that impacts this RFC is not an errata. The change appears to require a consensus decision on how to handle it. Thus rejected on formal grounds, should be considered if document is revised in the future.