v6 subnet size for DSL & leased line customers

Christopher Morrow morrowc.lists at gmail.com
Wed Jan 2 05:42:59 UTC 2008


On Jan 1, 2008 8:29 AM, Mark Smith
<nanog at 85d5b20a518b8f6864949bd940457dc124746ddc.nosense.org> wrote:
>
> On Tue, 1 Jan 2008 12:57:17 +0100
> Iljitsch van Beijnum <iljitsch at muada.com> wrote:
>
> >
> > On 31 dec 2007, at 1:24, Mark Smith wrote:
> >
> > > Another idea would be to give each non-/48 customer the
> > > first /56 out of each /48.
> >
> > Right, so you combine the downsides of both approaches.
> >
> > It doesn't work when ARIN does it:
> >
>
> Well, ARIN aren't running the Internet route tables. If they were, I'd
> assume they'd force AS6453 to do the right thing and aggregate their
> address space.
>

11920 - cogeco who I presume (just guessing) is doing this either
because they have not aggregated by mistake or have to shed load and
load-balance). I don't think teleglobe (6453) is at fault here...

out of curiousity how is this sort of thing supposed to be done in v6?
(traffic engineering given the '1 prefix per ISP' standard mantra)

>
> > *  24.122.32.0/20   4.68.1.166               0             0 3356 6453
> > 11290 i
>
> Static assignments of /56 to customers make sense to me, and that's the
> assumption I've made when suggesting the addressing scheme I proposed.
> Once you go static with /56s, you may as well make it easy for both
> yourself and the customer to move to a /48 that encompasses the
> original /56 (or configure the whole /48 for them from the outset).

I think the assumption most folks make with DSL/cable is that
end-users get dynamic assignments from a local (to the PE device)
pool, similar to ipv4. I suppose you could do static assignments, but
there's a management payment there that might not fit within the ISP's
cost plan.  I presume that something accepting PD would be smart
enough to let the end-hosts/lans know when their top 56 bits
changed... and v6 includes auto-renumbering for 'free' right? So all
solved?

(yes some of that is joking... or at the very least pointing out a gotcha)

-Chris



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