Practical numbers for IPv6 allocations

Tue Oct 6 04:43:16 UTC 2009

On Mon, Oct 5, 2009 at 11:39 PM, Doug Barton <dougb at 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