--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 that this will be the case and overly constrain home users. In addition, part of the popularity of NAT has resulted from its allowing a consumer to simply "plug in" a new network to an existing network. But the popularity of NAT in IPv4 has also greatly limited the ability of the IPv4 network to support new applications, and increased the expense required to support others. A lot of the value add in IPv6 results from its having enough address bits that NAT is no longer necessary. But if we constrain home users to the point that they see a benefit from NATting, we will have destroyed much of the additional value of IPv6.
Keith, 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. Now that number goes down significantly --and I would agree with your assertion-- if we were still assuming the use of hardware-assigned MAC addresses to populate that space. But we largely are not. The use of NAT to expand address space in residential use of IPv4 has been largely to expand one or two addresses into around 2**16. Even those of us who run several subnets with different security policies don't often use that much space up. While we clearly could in the future, and I don't like NATs much more than you do, a /64 gives 48 bits of headroom -- over a dozen decimal orders of magnitude if my mental arithmetic is correct -- above any regularly-demonstrated current need. That is a lot of headroom, enough that the assertions above are not obviously true, at least without a lot more rationale. That doesn't mean I'm convinced that shifting the boundary is either necessary or desirable. But I don't think hyperbole helps the discussion. john