ARIN-PPML Message

[ppml] Fwd: Keeping in reserve

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.