subnet prefix length > 64 breaks IPv6?

Glen Kent glen.kent at
Sat Dec 24 14:48:40 UTC 2011

> 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?


> 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.

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