Re: Aggregating channels...

["Arvid Grøtting" <arvidg@netfonds.no>]

Henning Brauer <lists-openbsdtech@bsws.de> writes:

> Well, a /25 will be quite often filtered - it's just to small. However, 50%
> of the routing table consists of routes smaller /20, and at least 30% are
> /24 routes, so any provider filtering these is just plain stupid.

Not necessarily.  For e.g. 80/8 (a block of addresses currenly
allocated by RIPE for PA addresses), the default and minimum
allocation size -- as defined by RIPE -- is a /20.  Any sane provider
with address space within 80/8 will announce a /20 or larger
aggregate.  Normally, addresses within the aggregate will be reachable
at least from the provider announcing the aggregate.  In a perfect
world, it could make sense for a service provider -- at least for one
placed outside the RIPE service region -- to filter out anything more
specific than a /20 within 80/8.

Of course, ours is not a perfect world and there do seem to be
providers within 80/8 that don't announce all of their /20 as they
should.


-- 

Arvid