On Mon, Oct 5, 2009 at 11:39 PM, Doug Barton <dougb@dougbarton.us> wrote:
As a practical matter we're "stuck" with /64 as the smallest possible network we can reliably assign. A /60 contains 16 /64s, which personally I think is more than enough for a residential customer, even taking a "long view" into consideration. The last time I looked into this there were several ISPs in Japan who were assigning /60s to their residential users with good success. OTOH, a /56 contains 256 /64s, which is way WAY more than enough for a residential user. The idea that a residential user needs a full /48 (65,536 /64s) is absurd. OTOH, assigning a /48 to even a fairly large commercial customer is perfectly reasonable. This would give them 256 /56 networks (which would in turn have 256 /64 networks) which should be plenty to handle the problems of multiple campuses with multiple subnets, etc.
Keep in mind that not all 'fairly large enterprises' are willing to sit at a single ISP, they may have diverse offices on diverse network provider connections. They may want the easy of saying: 'All my address blocks are in 1.2.0.0/16' and not understand (or like) that they now have to deal with wierd routing and addressing problems because they can't get a /32 and break it up into /48's all over creation (different ISP's/links/etc) or deal with the split of address space they'd get from ISP /48 PA assignments. the enterprise world has changed quite a bit from IPNG's early days... Someone who runs a large Enterprise with global office locations and who's actually deploying ipv6 internally/externally ought to give a presentation at NANOG and/or IETF. I don't disagree with the math I snipped, I do appreciate you laying it out, and I don't think that there are a super large number of folks in the scenario I layed out above. I've seen quite a few at previous employers though... -Chris