[ppml] Fwd: Keeping in reserve

David Conrad drc at virtualized.org
Thu Oct 5 12:17:34 EDT 2006

Is there any reason PI /48s shouldn't be allocated with the bisection  
method, thus removing the need to reserve space?


On Oct 5, 2006, at 3:14 AM, Iljitsch van Beijnum wrote:

> Hi,
> 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.
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