I am not sure why it is useful but nothing stops you from adding more loopback addresses:

root@jump2:~# ip addr add ::2/128 dev lo
root@jump2:~# ping6 ::2
PING ::2(::2) 56 data bytes
64 bytes from ::2: icmp_seq=1 ttl=64 time=0.043 ms

While I am not sure what use extra addresses from the 127.0.0.0/8 prefix are on the loopback, it is quite common for us to add extra global addresses and then use that with proxy arp. Of course that is only necessary on IPv4 since IPv6 isn't so restrained that we have to save every last address bit using tricks.

 

root@jump2:~# ip addr add ::1234/128 dev lo
root@jump2:~# ping6 ::1234
PING ::1234(::1234) 56 data bytes
64 bytes from ::1234: icmp_seq=1 ttl=64 time=0.046 ms

:-)

 

With IPv6 you can use fe80::1:aaaa for link local and fd00::1:0:1234 for your RFC1918 like setup. And then you can use 1:1 NAT to transform that to GUA on the router. Even NAT, if you insist on using it, is better with IPv6.

The confusion here appears to be that auto generated link local prefixes are long with many hex digits. But compared to the new proposal, which could have no auto generated link local due to having too few bits, there is nothing that stops you from manually assigning link local addresses. It is just that nobody wants to bother with that and you wouldn't either.

Example:

root@jump2:~# ip addr add fe80::1:aaaa/64 dev eth0
root@jump2:~# ping6 fe80::1:aaaa%eth0
PING fe80::1:aaaa%eth0(fe80::1:aaaa) 56 data bytes
64 bytes from fe80::1:aaaa: icmp_seq=1 ttl=64 time=0.033 ms

I am not aware of any NDP attacks that would be any different if based on ARP. Those two protocols are practically the same.

Regards,

Baldur