Den 6. mar. 2016 13.41 skrev "Karl Auer" <kauer@biplane.com.au>:
Dunno about "harsh", but RFC 2464, section 4 says that the prefix must be 64 bits. By (extremely strong) implication, a host must not use a prefix of any other length to perform SLAAC. I say "extremely strong" because the entire description of how an IPv6 Ethernet interface identifier is formed depends on it being composed of the prefix plus an EUI-64 identifier. Later RFCs firm up the requirement and apply it in other contexts.
But the most popular OS (Windows) completely ignores all of that and makes up an identifier not based on EUI-64. Everyone are happy anyway. The RFC should have let identifier selection as an implementation detail as the risk of collision is almost non existent given a sufficient random selection and we have duplicate address detection as a safeguard. Regards Baldur