v6 subnet size for DSL & leased line customers

Mark Smith nanog at 85d5b20a518b8f6864949bd940457dc124746ddc.nosense.org
Thu Dec 20 21:13:24 UTC 2007

On Thu, 20 Dec 2007 12:26:43 +0900
Randy Bush <randy at psg.com> wrote:

> > I work on a network with 100K+ DSL folks and 200+ leased line
> > customers, plus some other stuff.  The leased line customers are
> > increasing dramatically.  I should plan for a /64 for every DSL
> > customer and a /48 for every leased line customer I expect over the
> > next 5-7 years?
> why not a /56 by default for both, and give them an opportunity to
> justify more?

Why not a /48 for all? IPv6 address space is probably cheap enough that
even just the time cost of dealing with the occasional justification
for moving from a /56 to a /48 might be more expensive than just giving
everybody a /48 from the outset. Then there's the op-ex cost of
dealing with two end-site prefix lengths - not a big cost, but a
constant additional cost none the less.

> a /64 is a bit old-think unless you are having cost issues getting your
> space from above.


        "Sheep are slow and tasty, and therefore must remain constantly
                                   - Bruce Schneier, "Beyond Fear"

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