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Stephen Sprunk stephen at sprunk.org
Thu May 31 13:45:43 UTC 2007

Thus spake "Brandon Butterworth" <brandon at rd.bbc.co.uk>
>> > Don't give people an excuse to deagg their /32
>> RIPE may only give out /32's but ARIN gives out /48's so there wouldn't 
>> be
>> any deaggregation in that case.
> That's not what I said. If /48 are accepted by * then people with
> a /32 or whatever will deagg to /48.

The general rule, for both v4 and v6, is that people should filter on 
whatever the minimum allocation/assignment size for each RIR block.  It's 
also been suggested that you accept a few more bits for routes with a short 
AS_PATH length to help with TE, but that's optional.

Someone recently posted a link (either on PPML or here -- I can't find it 
now) that showed ARIN's minima for the various v4 and v6 blocks.  The v4 
ones were all over the map, but there are relatively few v6 blocks and all 
of them are /32 except for one that's /48.

The upside is that in the block you're expected to accept /48s, nobody will 
have a /32.  The downside is that anyone who gets a larger-than-minimum 
sized allocation/assignment can deaggregate down to that level.


Stephen Sprunk      "Those people who think they know everything
CCIE #3723         are a great annoyance to those of us who do."
K5SSS                                             --Isaac Asimov 

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