> So, I really don't see why LAN segments *need* /64s either then. LAN > segments will never have 2^64 nodes on them either - most only have no > more than a few hundred nodes.
IPv6 LAN segments do not *NEED* a /64. IPv6 LAN segments *ARE* a /64 by definition. It has nothing to do with the number of nodes which are irrelevant in IPv6. Those 64 bits that are not part of the /64 network prefix, are "interface IDs" which address network interfaces connected to the network. Currently, most hardware implements IPv6 in the simplest and most general way so that people who want to use it in a non-standard way can munge things up, but if you are running an IPv6 transit network that connects to the IPv6 Internet, then you are better off sticking with standards. In any case, a single host could easily have 36 or more IPv6 interface IDs on it, given the prevalence of 4-core servers capable of holding 32 gigs of RAM and virtualizing 12 machines per core. And given the rate of technology change, that number (36) is doubling every couple of years. Future proof your network and use /64 for every network segment even if it is only a point-to-point link unless there is a valid technical reason to make an exception. Conserving address space is not a technical reason. Ten years from now, nobody will thank you for conserving addresses that aren't going to be scarce for another two to three human lifetimes (100-200 years). But they will thank you for making the network architecture simple and expandable. There might even be a good reason to change some point-to-point circuits into multipoint circuits once Ethernet and MPLS have swept aside the dregs of SDH/PDH/ATM/FR. --Michael Dillon -------------------------------------------------------------------- IETF IPv6 working group mailing list [email protected] Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
