--On Saturday, 25 August, 2007 13:08 -0400 Keith Moore <moore@cs.utk.edu> wrote:
John C Klensin wrote:
--On Saturday, 25 August, 2007 12:28 -0400 Keith Moore <moore@cs.utk.edu> wrote:
/64 is too small for a home network. It might indeed turn out that it's possible to bridge several different kinds of media on a single subnet, but it's bad planning to assume ... Will all due respect, even if you assume a "home" with ten occupants, a few hundred subnets based on functions, and enough sensor-type devices to estimate several thousand of them per occupant and a few thousand more per room, 2**64 is still a _lot_ of addresses.
And 2**45 prefixes under 2000:/3 is a _lot_ of prefixes. But the sheer number of addresses in a subnet or prefixes available to be assigned doesn't seem to be the limiting factor in either address block assignment or subnetting of leaf networks. Every level of delegation seems to eat a couple of address bits.
Yes. Of course. Again, I'm not convinced that this is a good idea, just trying to keep the discussion focused and real.
What bothers me about a /64 is not the scarcity of addresses, but the inability to subnet it. (and that, IMHO, was a poor design choice in IPv6, but I think it's rather late to revisit that choice, just like I think it's late to revisit /48.)
This gets to one of the issues I _am_ concerned about. While I didn't call it out explicitly in my response to Thomas, I believe that, if the RIRs start saying "give out /64s unless someone can prove to your satisfaction that they need a lot of subnets" to ISPs, we have ample evidence that some, perhaps many, ISPs serving the residential market will construe "prove to our satisfaction" as "pay us a lot of extra money". If that happens, our experience with IPv4 and NATs suggests to me that it will be a _very_ short period of time before devices hit the consumer market that either do subnetting on longer-than-/64 prefixes, are set up to handle some other model of address pools, or NAT (I'd predict all three and would find the middle one interesting) along with patches to stacks that support them as needed. Since we probably won't revisit the /64 subnetting choice, those patches will be made independent of any standard or IETF advice which suggests that there may be interoperability problems if there is any opportunity for them. And _that_ is bad news. It is also news that reinforces my response to Thomas: there really are architectural issues in this sort of decision and no one I know of has chartered the RIRs to make those types of architectural decisions. john