[ppml] Fwd: Keeping in reserve
I understand that ARIN wants to give out /48s for PI but reserve a /
44. That's a bad idea, see the message below about this that I sent
to the RIPE address policy list.
Begin forwarded message:
> History, both in IPv4 and IPv6, has shown that keeping space in
> reserve to accommodate future request doesn't work very well:
> people often end up announcing several blocks anyway. So let's not
> waste the space and make filtering harder by doing this. Also,
> since a /48 is an incredible amount of space to begin with, coming
> back for more should be rare in IPv6.
> The advantage of only giving out /48s with no unused space between
> them is that if, for instance, 12000 /48s are given out, that will
> be from a single /34 and allowing /48s from a /34 allows 16384
> routes, while allowing /48s from a /20 (because for every /48 of
> 12000 a /32 is kept in reserve) allows 268 million routes, more
> than enough to overload any reasonable routing system in an attack.