[address-policy-wg] IXP pool lower boundary of assignments

* David Farmer

> So, if an IXP starts with three(3) participants, per policy, with a
> /29, it is already at 50% full, leaving 3 addresses for growth, and
> that doesn't include any infrastructure IP addresses, like a route
> server(s), etc...

Exactly, a tiny IXP with three founding members would have enough space
to double in size before needing to renumber out of an initial /29.

For a slightly larger IXP with six founding members (or four founding
members + two route servers and so on), the situation would be exactly
the same - it would have enough space to double in size before needing
to renumber out of an initial /28.

And so on…

(BTW: «founding member» here means «connects within the first year»)

> Therefore, starting at a /28 makes more sense to me. Forcing most
> IXPs to renumber almost right out of the gate doesn't make much sense
> to me.

It seems that you assume here that all/most IXPs will grow out of an
initial /29 and therefore require renumbering «right out of the gate».
If that was the case, I would not suggest /29 as the default. However,
Matthias's numbers seem to suggest otherwise, with plenty of IXPs
(~25%) managing just fine with a /29.

This does not surprise me all that much. If you set establish IXP in
some rural location (in Longyearbyen, let's say), there is an almost
zero percent chance there will be more than six members connecting in
the foreseeable future because there are so few operators servicing
that area.

While AMS-IX, DE-CIX, LINX, Netnod and the like are probably what
springs to mind when one says «IX», it would appear that behemoths like
those are exceptionally rare and few in numbers compared to the small
ones with just a handful of members, and I think it would be wise to
keep that in mind when developing this policy further.

Anyway, for the IXPs that *would* grow out of an /29, it's not like
renumbering is *that* hard. Current policy grants 180 days to complete
the renumbering, and when the IXP is just 4-5-6 members, it would even
be doable to just gather everyone on a teleconference call and just do
it all together.

> Finally, maybe there should be a maximum allocation size of /24.

Policy currently has a maximum limit of /22, for what it is worth. So
even the behemoth IX-es with up to 1K members are catered to by this
policy. I'm fine with that.

Tore