Xu Xiaohu wrote : > The following statement is quoted from RFC 4291: "IPv6 nodes are not > required to validate that interface identifiers created with modified > EUI-64 tokens with the "u" bit set to universal are unique. > > The use of the universal/local bit in the Modified EUI-64 format > identifier is to allow development of future technology that can take > advantage of interface identifiers with universal scope." > > Till now, we haven't known the real usage of this constraint yet. So > we should reverently obey such a constraint whose future usage is > still uncertain.
Two points: 1. This sentence doesn't concern addresses that, like IPv4-mappable addresses, are never subject to any neighbor discovery protocol. 2. Relevance of this sentence seems negated in RFC 2462 where, in the specification of IPv6 stateless autoconfiguration, we have (upper cases added): "To insure that all configured addresses are likely to be unique on a given link, NODES RUN a "duplicate address detection" algorithm on addresses before assigning them to an interface. The Duplicate ddress Detection algorithm is performed on ALL addresses, independent of whether they are obtained via stateless or stateful autoconfiguration." Indeed, not checking uniqueness of IPv6 addresses when they are MAC-address derived would be a bad idea: MAC addresses cannot be assumed to be really universal because they can be administratively configured in some hosts. > Look forward to a clear conclusion after discussing it in the 6man > mailing-list. Agreed. Best regards, RD -------------------------------------------------------------------- IETF IPv6 working group mailing list [email protected] Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
