Robert,

There are a number of advantages of non-/64 for p2p. For example, you can have an easy address allocation scheme like ...: <routernumber>:<index>:<host id>" which does not require any bookkeeping. That's not possible with /64 addresses.

You are completely mistaken. Using your own example: Hostid = 0xcafe Index = 0x77 Routernumber = 0xbeef I'll even go over an EUI-64/RFC2373 example although it's going to be obsolete real soon. +-----+---------+---------+-------+--------------+ | 8 | 16 | 16 | 8 | 16 | | | hostid | | index | routernumber | +-----+---------+---------+-------+--------------+ 02 ca : fe FF : FE 77 : beef The long way: ------------- cisco3640#conf t cisco3640(config)#inte e0/0 cisco3640(config-if)#mac-address ca.fe77.beef cisco3640(config-if)#ipv6 address 2001:db8::/64 eui-64 cisco3640(config-if)#end cisco3640#sh ipv6 inte e0/0 Global unicast address(es): 2001:DB8::2CA:FEFF:FE77:BEEF, subnet is 2001:DB8::/64 ^^ ^^ ^^ ^^^^ \\|| || |||| CAFE 77 BEEF The short way: cisco3640#conf t cisco3640(config)#inte e0/0 cisco3640(config-if)#ipv6 address 2001:db8::02CA:FEff:fe77:BEEF/64 This is compliant with EUI-64 and RFC 2373. As I said before, we're talking about straight EUI-64 here and this is soon to be obsoleted. The replacement for RFC2373 (draft-ietf-ipngwg-addr-arch-v3-11.txt) uses _modified_ EUI-64, and you can do almost whatever you want, such as: ipv6 address 2001:db8::02CA:FE00:0077:BEEF/64 ipv6 address 2001:db8::02:CAFE:77:BEEF/64 ipv6 address 2001:db8::1/64 All of which are compliant modified EUI-64 addresses.

The standard also requires EUI-64 addresses which is clearly not desirable for a number of application. For example, it would be very silly to require a change all your peering sessions just because you change your NIC.

There is no relation. You can construct an EUI-64 or a modified EUI-64 address without using the BIA, what's your problem here? Michel.