ipv6 addressing - non-routable equivalents?

[Matt Crawford]

> If I recall the IPv6 RFC correctly you can ues part of the last 64 bits
> for multiple addresses on a single computer.

No.  All 64 bits are for multiple interface identifiers on the same
subnet.  If some of those interfaces happen to belong to the same
host, that's all right.  If some of them identify the same interface,
I guess that's all right too, but isn't HTTP 1.1 prevalent enough
that the usual reason for this can finally go away?  Maybe not...

> As you know the last 64 bits of an IPv6 address are taken from the
> computers MAC address (if you wish to allocate in that manner). But a MAC
> address is only 48 bits long, leaving a tasty 8 bits.
> 
> As I understand it the computer *can* use these 8 bits to allocate
> multiple addresses without too much further configuration. How you do this
> in pratice though, I have no idea as I haven't looked into it.

No.

For IPv6 addresses beginning with 001 binary, the bottom 64 bits ARE
an EUI-64 with its 7th bit (the Universal/Local bit) flipped.  A
certain portion of EUI-64 space is reserved by the IEEE to denote a
48-bit MAC address, and that's the origin of the 0xfffe in the middle.

Any EUI-64 with the 7th bit equal to '1', which corresponds to an
IPv6 interface identifier with that bit '0', is locally controlled.
If you configure an interface to use such an identifier, the RFC 2462
DAD process will check for duplicates on the link.