The IEEE Guidelines for Use of Extended Unique Identifier (EUI), Organizationally Unique Identifier (OUI), and Company ID (CID) [PDF] have a section titled, "Mapping an EUI-48 to an EUI-64". This section starts:
Mapping an EUI-48 to an EUI-64 is deprecated.
And yet, use of this algorithm for converting EUI-48 to EUI-64 in order to form "interface identifiers" seems to be codified in IPv6 standards (see appendix A).
The IEEE documentation states that the mapping algorithm is deprecated because,
Mapping an EUI-48 assigned with an MA-S/OUI-36 or MA-M assignment to an EUI-64 potentially creates a duplicate of an EUI-64 assigned with a different MA-S/OUI-36 or MA-M. The IEEE RA has taken appropriate actions to mitigate creation of duplicates based on this mapping but, to protect the integrity of EUI-64 identifiers, this mapping is deprecated.
- How is it possible that there could ever be a duplicate EUI-64 when using this algorithm, assuming all parties correctly and completely follow the IEEE standards?
- Why does IPv6 specify the use of this "deprecated" algorithm for converting EUI-48 to EUI-64? Or is use of this algorithm not technically, officially part of IPv6? (IMHO it is absolutely a de facto standard, in any case, but here I am asking about the de jure standard, so-to-speak.)