SLAAC only works with /64 - yes - but only if it runs on Ethernet-like Interface ID's of 64bit length (RFC2464).
Ok, the last 64 bits of the 128 bit address identifies an Interface ID which is uniquely derived from the 48bit MAC address (which exists only in ethernet).
SLAAC could work ok with /65 on non-Ethernet media, like a point-to-point link whose Interface ID's length be negotiated during the setup phase.
If we can do this for a p2p link, then why cant the same be done for an ethernet link? Glen
Other non-64 Interface IDs could be constructed for 802.15.4 links, for example a 16bit MAC address could be converted into a 32bit Interface ID. SLAAC would thus use a /96 prefix in the RA and a 32bit IID.
IP-over-USB misses an Interface ID altogether, so one is free to define its length.
Alex
Regards, K.